Promoting Medication Adherence in the Elderly: Factors and Insights From a Cross‐Sectional Study

ABSTRACT

Objectives

This study reviewed the factors involved in medication adherence among the elderly. By understanding these factors, we can develop targeted strategies to promote better medication adherence, ultimately improving health outcomes for this population.

Methods

This cross‐sectional study was performed in 2023. In the first phase, five scientific databases were searched: PubMed, Science Direct, Springer, Wiley, and Wolters Kluwer. The review included articles published between 2001 and January 2022. The keywords used in the searches included “drug adherence,” “medication adherence,” “elderly,” and “older adults.” Two researchers independently evaluated the titles, abstracts, and texts of papers. Specific inclusion and exclusion criteria determined the selection of studies. Data were extracted using a data extraction form based on the study objectives. From all 116 articles retrieved, 68 studies were included. In the second phase, factors on medication adherence in the elderly were divided into categories and subcategories.

Results

Factors involved in medication adherence among the elderly were divided into two categories: personal and external factors. Personal factors were classified into three subcategories: reducing, increasing, and other, while external factors included cultural, social, and economic factors as well as the influence of others. The most important factor associated with medication non‐adherence among the elderly is polypharmacy. Other factors such as economic and social status, cognitive impairment, health literacy, age, and depression also significantly influence medication adherence among the elderly.

Conclusions

The health system should focus on managing medications for older adults who use multiple drugs. Providing economic and social support, psychological training, and counseling can ameliorate medication adherence.

The present study reviewed the factors of medication adherence in the elderly. By understanding these factors, we can develop targeted strategies to promote better medication adherence, ultimately improving health outcomes for this population.

Abbreviations

AD

Alzheimer's disease

ADR

adverse drug reactions

AF

atrial fibrillation

AHT

assistive health technology

BMI

body mass index

BPH

benign prostatic hyperplasia

CABG

coronary artery bypass graft

CPS

cyber‐physical systems

ESRD

end‐stage renal disease

FHL

functional health literacy

GS

geriatric syndrome

HIV

human immunodeficiency virus

HRQoL

Health‐Related Quality of Life

IMU

inertial measurement unit

IoT

internet of things

NFC

near field communication

OAB

overactive bladder

OAC

oral anticoagulant

OTC

over the counter

PRISMA‐ScR

Preferred Reporting Items for Systematic Reviews and Meta‐Analyses Extension for Scoping Reviews

RF

radio frequency

RFID

radio‐frequency identifier

SES

socioeconomic status

SPS

socialized prompting system

UHF

ultra high frequency

WHO

World Health Organization

WSN

wireless sensor network

1. Introduction

Globally, the elderly population is expanding progressively. The World Health Organization (WHO) projects that by 2050, individuals aged 60 years old and over will double, with those aged 80 years old and above reaching 426 million [1]. This demographic shift is related to an increased prevalence of chronic diseases, requiring long‐term medication regimens [2]. A pattern supported by evidence indicates that more than 80% of older adults have at least one chronic condition, with multimorbidity becoming more common in aging populations [3]. The rate of non‐adherence to medications among those with three or more chronic conditions has been reported to reach up to 70% [4]. Recent evidence highlights the influence of various factors—biological, psychological, and socioeconomic—in contributing to this trend [5, 6]. The impact of polypharmacy and health literacy on medication adherence highlights the necessity for updated frameworks to tackle these challenges [7, 8].

Medication adherence in the elderly with chronic diseases is a critical issue, with studies showing poor adherence rates of over 70% [9]. Since the elderly represent a substantial portion of the population affected by chronic conditions and associated complications, their medication adherence needs to be understood [10]. Poor adherence to medication in the elderly causes medication waste with increased healthcare costs and significant deterioration of disease, disability, or death [11]. In addition, it is a major challenge in treating elderly patients and a potential cause of hospitalization, a factor involved in increased morbidity and mortality among the elderly [12, 13]. Poor medication adherence is associated with adverse outcomes in elderly health and elevates the rate of falls as well as their vulnerability to adverse outcomes [14]. A major share of the elderly suffers from cardiovascular, respiratory, kidney, and blood pressure diseases. Managing these conditions requires primary and secondary prevention measures [12, 15, 16, 17]. Meanwhile, the elderly population is growing progressively. As this population grows, support for the elderly who live alone increases as well, resulting in a higher possibility of physical and mental chronic diseases in the elderly who require long‐term drug therapy. As such, medication adherence is crucial for this population. The correct use of medicine as one of the essential critical factors for the self‐management of chronic diseases minimizes premature death and the social burden of the disease in the elderly. Overall, it is of utmost importance to understand the main reason for non‐adherence in increasing medication adherence [18, 19, 20].

Medication adherence in the elderly refers to whether patients take their medications as prescribed (e.g., twice a day) and whether they continue to take them. Adherence broadly covers patients' decisions about starting or not starting health care recommendations and how they maintain the recommended health behaviors after initiation [19, 21].

The significance of medication adherence in the elderly is owing to its positive impacts on their quality of life. It leads to the modification of complex drug regimens and, as a result, saves the cost of drug consumption [22]. Additionally, implementing self‐care programs for the elderly with medication adherence has strengthened and is vital in preventing, treating, and mitigating disease complications [23].

Medication adherence in the elderly enhances their ability to participate in medical treatment for their diseases and improves their positive attitude toward complementary and alternative therapies. As a result, the elderly can actively participate in treating their disease [2]. Medication adherence improves the quality of life, color vision, driving, and social functioning [24]. The decline in the hospitalization rate, the duration of hospital stays, and the reduction in hospitalization expenses in the elderly who follow their medication regimen well demonstrates the importance of medication adherence [25, 26].

Various factors in medication adherence of the elderly can be tracked and examined under the influence of various factors in various fields [27]. According to the WHO, there are five potential factors in non‐adherence: socioeconomic factors, treatment conditions, health system, and patient [28].

Findings suggest that many factors can influence drug use in older people. Since rational use of drugs is considered an essential point for the WHO and the Ministry of Health worldwide, drug sustainability is a critical issue across the entire population as well as the elders. It is associated with various backgrounds and factors in a society; failure to identify these factors can result in elevated rates of death, disability, and high costs due to drug side effects [29].

The factors on medication adherence in the elderly are those that can affect the degree to which older adults take their prescribed medications as instructed by their healthcare providers. Medication adherence is essential for the health and well‐being of the elderly, as it can affect the outcomes and costs of their treatments. However, medication adherence can be challenging for the elderly, as they may encounter various barriers and difficulties, such as cognitive impairment, sensory decline, polypharmacy, complex regimens, side effects, cost, and lack of social support [30].

Satriani et al.'s study presented the effect of health literacy on medication adherence in the elderly [31]. The importance of the self‐efficacy factor on medication adherence in the elderly has been emphasized in the study by Roseli et al. [32]. In Kasilov's study, the active memory factor has been known to strengthen medication adherence [33]. In contrast, Gardner et al. have introduced polypharmacy as a factor in poor adherence [34]. Zhao et al. reported that factors such as geographic location, education, marriage, year of diagnosis, race, and ethnicity would affect medication adherence in older women with breast cancer undergoing hormone therapy [35]. Sheilini et al. demonstrated the importance of nurses' being informed about high blood pressure and its impact on adherence to antihypertensive drugs in older adults. Al‐Ruthia et al. emphasized the effect of treatment satisfaction on medication adherence in the elderly [36]. Emadi et al.'s study also pointed out the importance of telepharmacy services on medication adherence in the elderly [37]. The research of Morris et al. also emphasizes the effect of pharmacist‐led interventions at home on medication adherence in the elderly [38].

Given the importance of adherence in the elderly, this study, undertaken in 2023 to examined factors on medication adherence across this population to inform the development of targeted strategies for enhancing adherence and health outcomes.

2. Materials and Methods

This cross‐sectional study was performed in 2023. Factors on medication adherence in the elderly were developed via a two‐stage process: (1) scoping review, (2) classification of data elements.

2.1. Scoping Review

A scoping review followed the methodological framework proposed by Arksey and O'Malley [39], which consists of five main steps and one optional step as below:

• Identifying the research question.

• Identifying relevant studies.

• Selecting the studies.

• Charting the data.

• Collecting, summarizing, and reporting results

2.1.1. Identifying Research Questions: The Review Addressed the Following

What are the key personal and external factors on medication adherence in the elderly?

This question was developed to explore both personal and external factors on medication adherence, providing a comprehensive understanding to inform future interventions.

2.1.2. Identifying Relevant Studies

The study selection process of this research was performed in 2023 using the PRISMA extension for Scoping Reviews (PRISMA‐ScR) checklist [40]. The PubMed, Science Direct, Springer, Wiley, and Wolters Kluwer databases were reviewed. Based on MeSH, keywords were determined in English sources, including drug adherence, medication adherence, elderly people, and old people. The keywords used to search for articles are listed in Table 1.

TABLE 1.

Search strategy in scientific databases.

Criteria	Time	The search was conducted from 2001 to January 2022
	Language	English
	Databases	PubMed, Science Direct, Springer, Wiley, and Wolters Kluwer
#1		“Drug adherence” OR “Medication adherence” OR “Medication compliance” OR “Drug compliance.”
#2		Aged OR Elderly OR “Elderly people” OR “Older adults” OR “Older people” OR “Aging population”
Search		#1 AND #2

2.1.3. Selecting the Studies

The entry criteria for selecting articles into the research included articles published in English between 2001 and January 2022. The studies aimed to explore the factors affecting medication adherence in the elderly. These articles had been published in reputable research and academic journals, and their full text was readily available. The exclusion criteria for the study included articles that were required to provide adequate information about the factors of medication adherence.

During the screening stage, two researchers independently evaluated the titles of the retrieved articles and reviewed the abstracts separately. They also excluded irrelevant articles based on the study's inclusion and exclusion criteria. In the eligibility stage, two researchers independently reviewed the full text of the articles included. The initial step involved reviewing and selecting articles that met the inclusion criteria while excluding those that did not. Any disagreements about article selection were resolved by consulting a third independent researcher.

2.1.4. Charting the Data

The reviewer extracted the data from the studies, while the second reviewer checked the extracted data. Conflicts were resolved through discussions between two reviewers. We extracted data using a structured table format based on the following headings: publication year, study country, article title, first author's name, factors affecting drug adherence, and study conclusion. Factors on medication adherence were classified into two categories: personal and external factors. This classification was employed among reliable sources to categorize factors on medication adherence among the elderly [13, 41, 42, 43, 44, 45, 46, 47, 48, 49]. The rest of the factors on medication adherence in the elderly, which were extracted from other selected articles, were considered sub‐divisions of these two main titles, with each factor extracted from other selected articles being distributed under personal and external factors based on thematic relevance. Then, using SPSS statistical software, statistical analysis was performed on the results of the articles, whereby the average effect of factors on medication adherence in the elderly was calculated in terms of percentage; it included the ratio of the impact of each factor on the total factors on medication adherence in the elderly.

2.1.5. Collecting, Summarizing, and Reporting Results

Based on descriptive analysis, the frequency of each factor extracted from studies on medication adherence in the elderly was determined. Subsequently, the frequency ratio of each factor relative to 68 studies was calculated as a percentage and presented in graphs as well as tables.

2.2. Classification of Factors on Medication Adherence

Using an expert sampling method, we administered the questionnaire to five specialists in Health Information Management, each with at least 5 years of experience. We also consulted with two geriatric care specialists, each possessing a minimum of 5 years of experience. Factors on medication adherence in the elderly were divided into categories and subcategories.

3. Results

3.1. Scoping Review

3.1.1. Summary of the Study Characteristics

An initial search in the four databases found 116 papers, which were then imported into the reference management software EndNote X8. After removing duplicates and unrelated articles based on their titles, abstracts, and texts, 68 papers were ultimately selected. Figure 1 displays the workflow of the paper selection.

FIGURE 1.

PRISMA flow diagram of scoping literature search and selection.

3.1.2. Sources of the Studies

Most of the studies had been conducted in the USA [2, 16, 22, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62] and the others had been carried out in Canada [17, 63], Australia [64, 65], Iran [27, 29, 66, 67], Singapore [10, 68, 69], Portugal [70, 71, 72], India [11], Saudi Arabia [73], Korea [23, 43, 74, 75, 76, 77], Switzerland [15], Netherlands [78], UAE [79], Germany [19], Indonesia [31], Brazil [80, 81], Russia [33], Poland [82, 83, 84, 85], China [86, 87, 88, 89, 90], Italy [91, 92], Japan [93, 94, 95, 96, 97], England [34], Spain [98, 99], Denmark [100], and Turkey [101, 102].

Figure 2 depicts the frequency of article publications over the years, ranging from 2001 to 2022. The most frequently published articles in this field were in 2020, with 13 articles.

FIGURE 3.

Factors on medication adherence among the elderly.

Table 2 outlines the general information of the articles included in the study. The earliest study belongs to 2001, while the most recent study was published in 2022. All studies aimed to examine the factors affecting medication adherence in the elderly.

TABLE 2.

Findings of the studies conducted on factors affecting medication adherence in the elderly.

No.	Authors	Publication year	Country	Aim	Factors extracted from studies on medication adherence in the elderly	Results
1	Chang et al. [16]	2011	USA	Assessing the critical role of kidney function in sustained medication adherence among elderly patients' post‐myocardial infarction, a crucial area of research in geriatric medicine	Long‐term use of the drug	With the long‐term use of drugs following myocardial infarction in the elderly with kidney dysfunction, these patients become vulnerable to the adverse clinical consequences of the disease, and their drug adherence diminishes
2	Ivers et al. [17]	2013	Canada	Evaluating how the duration of initial prescriptions at discharge influences long‐term medication adherence in elderly coronary artery disease patients	Long‐term use of the drug	Since the elderly's adherence to secondary cardiac prevention drugs after discharge from the hospital declines over time, the longer the prescription of secondary cardiac prevention drugs at the time of hospital discharge, the higher the probability of long‐term adherence in the elderly
3	Qin et al. [64]	2020	Australia	Exploring the factors contributing to the continuous use of renin‐angiotensin system inhibitors and β‐blockers in senior patients' post‐heart failure hospitalization	Long‐term use of the drug	Given the prevalence of unfavorable post‐discharge medication adherence among the elderly hospitalized for HF, strategies to improve long‐term medication adherence in the elderly with HF are warranted, particularly in older patients with comorbidities
4	Bastani et al. [29]	2021	Iran	Identifying the key factors determining medication adherence effectiveness in elderly populations	Personal and external factors reducing drug consumption, consumption disorder, acceptance of consumption, negligence in consumption, forgetfulness in consumption, cultural and socioeconomic factors, factors increasing drug consumption	Two main factors are considered the main determinants of medication adherence: personal and external. In addition, six sub‐topics include: Consumption disorder. Acceptance of consumption. Negligence in consumption. Forgetfulness in consumption. Cultural and socioeconomic factors. The influence of others. Various personal and external factors can affect medication adherence in the elderly
5	Yap et al. [10]	2016	Singapore	Conducting a comprehensive review to identify the obstacles that impede medication adherence among older adults	Factors related to a person's perception of medication adherence	Medication adherence is an essential part of chronic disease management. Since the elderly make up a more significant proportion of the population with chronic diseases and multiple complications, understanding medication adherence in the elderly becomes essential. Barriers to medication adherence are classified into four main categories: patient factors, drug factors, physician factors, and system‐based factors
6	Hennein et al. [50]	2018	USA	Exploring the relationship between adherence barriers and cardiovascular risk factor management based on findings from the Framingham Heart Study	Depression	Among the elderly with hypertension, dyslipidemia, and diabetes, depression is considered a barrier to medication adherence, exacerbating CVD risk factors in the elderly
7	Lima et al. [71]	2016	Portugal	Investigating how mindfulness practices mediate medication adherence in patients with Alzheimer's disease	Cognitive impairment	Based on the evaluation of medication adherence based on compliance with the dose and frequency of the doctor's prescription, cognitive impairment is regarded one of the major obstacles in elderly patients with Alzheimer's disease (AD) who use oral medications. Taking medicine through the skin in these patients requires motor skills
8	Shruthi et al. [11]	2016	India	Evaluating medication compliance patterns among geriatric patients with chronic illnesses in tertiary care	Level of education, people's awareness of the disease and prescription drugs, functional disorder, side effects of the disease	Medication adherence positively correlates with people's educational status and awareness of diseases and prescribed medications. Among older adults with a spouse or family or without any functional impairment, it is higher for those with regular follow‐up visits and those who have not experienced any side effects
9	Algameel M [73]	2020	Saudi Arabia	Analyzing medication usage and adherence trends among elderly home residents	Appropriate medical care for Elderly living at home, lack of access to medical care	Lack of access to appropriate medical care for the elderly living at home is a factor that causes poor medication adherence, adverse side effects of the disease, and hospitalization
10	Balkrishnan R [2]	2011	USA	Identifying the primary predictors that influence medication adherence in elderly individuals	Race, drug cost, the doctor's opinion about the number and frequency of doses of prescribed drugs, insurance coverage, patient‐doctor relationship, dosage form, age and gender, socioeconomic status, comorbidities, number of patient visits with the doctor, attitude and beliefs related to health and illness	There is a correlation between medication adherence in the elderly and factors such as race, doctor's opinion on the number of prescribed medications, medication cost, insurance coverage, patient‐doctor relationship, dosage form, age, sex, socioeconomic status, comorbidities, number of visits with the doctor, knowledge, attitude, and beliefs related to patients' health
11	Lu et al. [87]	2020	China	Evaluating the effects of social isolation and loneliness on medication adherence in elderly patients with chronic conditions	Social isolation and loneliness	Social isolation and loneliness are considered an epidemic among the elderly with chronic diseases, which causes medication non‐adherence in them. Social isolation has a positive relationship with loneliness. Social isolation and loneliness are related but independent constructs. Interrelated psychosocial mechanisms explain the effect of medication adherence on social isolation and loneliness and the effective pathways of social isolation increase with the development of chronic disease
12	Song and Park [77]	2020	Korea	Comparing the effectiveness of two health literacy measurements in evaluating medication adherence among older adults	Health literacy, low income, multiple chronic diseases, vision problems	Low health literacy is associated with poor medication adherence. Low income, multiple chronic diseases, and vision problems are important factors related to medication adherence
13	Soones et al. [61]	2017	USA	Exploring how health literacy, beliefs, and cognitive functions are connected to medication adherence in older adults with asthma	Cognitive impairment, functional cognitive impairment, health literacy	Functional cognitive impairment and limited health literacy cause low adherence to asthma medications among the elderly
14	Mizokami et al. [103]	2016	Japan	Using medication regimen adherence to indicate cognitive impairment in elderly individuals	Cognitive decline and cognitive dysfunction	Cognitive abilities strongly affect medication adherence among the elderly. There is a direct relationship between medication non‐adherence, cognitive decline, and cognitive dysfunction in the early stages of the elderly
15	Jankowska‐Polańska et al. [83]	2016	Poland	Studying the relationship between cognitive function and adherence to anticoagulation therapy in atrial fibrillation patients	Cognitive impairment and age	Medication adherence is integral to the comprehensive care of elderly patients with atrial fibrillation (AF) who receive oral anticoagulants (OACs) and suffer from cognitive impairment. Cognitive impairment is an independent determinant of adherence to drug therapy in the elderly with AF. Beyond cognitive function assessment, poor adherence is linked to the patient's age
16	Cho et al. [43]	2018	Korea	Investigating the link between cognitive impairment and antihypertensive medication adherence in elderly patients without dementia	Cognitive impairment	Cognitive impairment can harm medication adherence in patients without dementia who have high blood pressure
17	Jankowska‐Polańska et al. [82]	2016	Poland	Evaluating how frailty syndrome affects medication adherence in elderly hypertensive patients	Socioeconomic status, comorbidities, age, physical limitation and frailty syndrome, weakness	High blood pressure affects about 80% of older adults over 80 years old. Diagnosis and treatment of these patients are difficult since about 55.88% do not adhere to treatment recommendations and medications due to their low socioeconomic status, comorbidities, age, physical limitations, and frailty syndrome. The prevalence of weakness in the elderly also negatively affects medication adherence in these patients. A higher level of weakness in elderly patients can determine lower adherence
18	Rajpura and Nayak [51]	2014	USA	Evaluating how illness perceptions, treatment beliefs, and illness burden impact medication adherence in elderly hypertensive patients	Disease burden, perception of health status and illness, and drug treatment.	The role of perceived disease burden, in addition to disease perception and drug beliefs in the elderly with high blood pressure, can influence the adherence to antihypertensive drugs and control high blood pressure in the primary and secondary prevention of cardiovascular disease. A more benign perception of the disease and a more significant perceived disease burden lead to poor medication adherence
19	Gentil et al. [63]	2012	Canada	Exploring the association between depressive and anxiety disorders and antihypertensive medication adherence in community‐dwelling elderly adults	Depression, anxiety	Non‐adherence to antihypertensive medications is significantly associated with depression and anxiety disorders
20	Son and Won [76]	2017	Korea	Evaluating how self‐efficacy mediates the relationship between depression and medication adherence in older Korean patients with hypertension	Depression, self‐efficacy	Depression negatively affects adherence to antihypertensive medications. Self‐efficacy has a mediating role in the association between depression and medication adherence in elderly patients with hypertension showing that depression and self‐efficacy are statistically significant predictors of medication adherence in older patients with hypertension
21	Forestal et al. [62]	2016	USA	Assessing initial medication adherence in elderly patients using PACE claim reversal data	Forgetfulness in consumption, electronic prescription	Electronic prescribing is linked to a higher rate of claim reversal and may result in poor initial medication adherence. Since electronic prescriptions are not presented to the pharmacy by the patient, they are more likely to be forgotten or not received. The growing acceptance of electronic prescriptions requires special attention, as it may be a factor involved in initial medication adherence in the elderly
22	Mojtabai and Olfson [52]	2003	USA	Analyzing how medication costs impact adherence and health outcomes among Medicare beneficiaries	Drug cost, insurance coverage	Over 2 years, more than two million elderly Medicare beneficiaries did not adhere to drug regimens because of their cost. This poor adherence was more common among beneficiaries with no drug or partial insurance coverage and was associated with poorer health and higher hospitalization rates. The risk of poor cost‐related adherence is particularly evident among low‐income beneficiaries with high drug expenditures
23	Burnier et al. [15]	2020	Switzerland	Investigating factors influencing drug adherence in elderly patients with hypertension	Cognitive impairment, depression, attitude, and beliefs related to health and illness	In elderly patients (over 80 years) with high blood pressure, impaired cognitive ability, depression, lack of belief, and health beliefs weaken medication adherence
24	Ownby et al. [54]	2006	USA	Identifying factors affecting medication adherence in memory disorder clinic patients	Memory	Memory problems in older adults, combined with other factors that cause non‐adherence, are considered one of the fundamental issues in older adults
25	Gerber et al. [53]	2010	USA	Exploring racial disparities in medication adherence among Medicare enrollees	Social support, race, demographic factors, health literacy, depression	There are racial differences in adherence to prescribed medication regimens among older African Americans, who were less likely to follow physician medication instructions than older whites. Demographic characteristics, health literacy, depression, and social support also affect medication non‐adherence
26	Lau et al. [68]	2014	Singapore	Studying how fear of intimacy with healthcare professionals affects elderly Chinese patients	Patient's attitude toward seeking help from professionals, marriage	An examination of the elderly's attitude toward seeking help from health care professionals and its effect on their ability to take care of themselves and medication adherence found that the elderly who were married and had arthritis had a significantly negative attitude toward seeking help from health care professionals compared to those who were not married and did not have arthritis. Older adults' fear of intimacy with professionals compromises the perceived ability of self‐care and medication adherence in the elderly
27	Eindhoven et al. [78]	2018	Netherlands	Analyzing age and gender differences in medication adherence post‐myocardial infarction, with a focus on treatment disparities for women	Age, gender	Age and gender cause medication non‐adherence after myocardial infarction in older women
28	Park et al. [75]	2013	Korea	Identifying predictors of medication adherence in older Korean hypertensive patients	Socioeconomic status, functional cognitive impairment, age, gender, memory, forgetfulness in consumption	In the elderly, a factor such as forgetting the dosage and other important factors, including socioeconomic factors, history of high blood pressure, and functional cognitive impairment, play a role in weakening medication adherence among those with high blood pressure. The impact of factors such as age and gender on drug adherence reveals that out of 241 patients, 44% are 75 years or older, and 60% are men. Memory is also considered a key factor for medication adherence among the elderly. In contrast to younger adults, unintentional non‐adherence is a significant problem for older adults to continue taking medication
29	Jiang et al. [93]	2020	Japan	Evaluating health inequalities among elderly type 2 diabetes patients in Japan	Socioeconomic status	The effect of socioeconomic status (SES) on health disparities in older adults with type 2 diabetes was examined—sexual health disparities among older Japanese diabetic patients. Individuals with worse SES had significantly poorer adherence to OHA medication (both sexes), a higher risk of hospitalization for diabetes complications (men), and a higher risk of in‐hospital death (both genders)
30	Han et al. [23]	2017	Korea	Investigating the relationship between health behaviors and medication adherence in elderly patients	Selected health behaviors, waist size, body mass index, obesity, smoking and alcohol consumption, physical activity	There is a direct relationship between selected health behaviors and medication adherence. The leading independent variables in this regard include waist circumference and body mass index (BMI) as indicators of obesity, smoking, drinking alcohol, and physical activity as the leading independent variables. Medication adherence is considered a dependent variable
31	Sengstock et al. [60]	2012	USA	Addressing under‐prescribing and non‐adherence issues post‐coronary bypass surgery in older adults and proposing strategies to enhance adherence	Tolerating drug‐to‐drug and drug‐to‐disease interactions, polypharmacy, difficulty in hearing and understanding, and remembering medication instructions	Medication instruction non‐adherence is expected in the elderly following coronary artery bypass graft (CABG) surgery. Factors such as difficulty in hearing and understanding, remembering medication instructions, receiving several medications simultaneously, tolerating drug interactions with other drugs, and drug‐disease interactions are effective on non‐adherence to medication in the elderly. Long‐term use of drugs after the patient's discharge from the hospital is regarded an essential factor in poor adherence to medication in the elderly
32	Hussain et al. [79]	2020	UAE	Evaluating the impact of health literacy on medication adherence in elderly Pakistani women with type 2 diabetes	Health literacy	Health literacy directly affects medication adherence in the elderly, especially women. Hence, the impact of health literacy on medication adherence has been evaluated to improve communication strategies for healthcare professionals during a patient consultation
33	Schönfeld et al. [19]	2021	Germany	Conducting a systematic review on the relationship between medication adherence and self‐reported health literacy in older adults	Health literacy	Self‐reported health literacy is associated with medication adherence, and there is a consistently positive association between both constructs in the elderly
34	Satriana et al. [31]	2021	Indonesia	Reviewing updated literature on how health literacy affects medication compliance in elderly hypertensive patients	Health literacy	Health literacy immediately affects medication adherence and use according to the recommended dosage in the elderly and improves medication adherence. The elderly with a higher level of health literacy will demonstrate greater adherence to medication and other treatments
35	Delavar et al. [66]	2020	Iran	Evaluating the impact of health literacy tailored to self‐management for medication adherence and blood pressure control in elderly hypertensive patients	Patient education according to health literacy	The study's findings show the effect of patient education through health literacy on medication adherence and blood pressure control in older adults with hypertension. As an effective intervention, this factor enhances medication adherence and reduces both the average systolic and diastolic blood pressure in these adults
36	Jin et al. [74]	2016	Korea	Identifying factors that influence medication adherence in elderly populations	Functional health literacy, satisfaction with patient counseling, education status, and level, sufficient information and explanation about drug use, awareness of drug dosage frequency, health‐related problems	There is a direct relationship between Functional Health Literacy (FHL) and medication adherence in elderly patients. This adherence pertains to other factors such as education level, health‐related problems, dosage frequency, satisfaction with patient counseling, and sufficient information and explanation about drug use
37	Aktaş and Berivan Bakan [101]	2021	Turkey	Exploring the relationship between attitudes toward medication adherence and using complementary plus alternative medicines in elderly patients with chronic diseases	Attitudes and beliefs related to health and illness	A positive attitude toward complementary and alternative medicines among elderly individuals with chronic diseases enhances their participation in medical treatments
38	Valassi et al. [81]	2019	Brazil	Investigating factors linked to medication adherence in retired elderly outpatients in São Paulo, Brazil	Socioeconomic status, household income	Medication adherence among the elderly with high household income results in an understanding of medication adherence patterns
39	Oori et al. [67]	2019	Iran	Developing a conceptual model of medication adherence for older adults with high blood pressure through an integrative literature review	Interpersonal, organizational, and social factors, behavioral factors, biological factors, psychological factors, knowledge factors, factors related to the disease, medication, and individual treatment	Personal, interpersonal, organizational, and social factors affect adherence to medication in controlling high blood pressure. Personal factors constitute the most common predictors in the subgroups of behavioral, biological, psychological, knowledge, disease‐related factors, medication, and individual treatment. However, interpersonal, organizational, and social factors can have indirect and essential effects on medication adherence in the elderly
40	Branin [58]	2001	USA	Evaluating the role of memory strategies in enhancing medication adherence in elderly individuals	Depression, anxiety, memory	The elderly use memory strategies as a compensatory mechanism to cope with age‐related memory decline. They use more internal memory strategies and prefer event‐based medication instructions over time‐based medication instructions. Depression, anxiety, and memory are significant predictors of the type of medication adherence strategies among the elderly
41	Kosilov et al. [33]	2020	Russian Federation	Analyzing how executive functions, working memory, and other factors impact medication adherence in older adults with benign prostatic hyperplasia and overactive bladder symptoms	Memory	This study found that the executive function of the working memory factor is effective in medication adherence in older men with benign prostatic hyperplasia (BPH), and the symptoms of overactive bladder (OAB) are significantly reduced. Predictor variables significantly influencing older men's adherence to BPH and OAB treatment include executive function and working memory composition, severe lower urinary tract symptoms, and age
42	Saffari et al. [65]	2019	Australia	Investigating how religious coping and home environment affect quality of life and medication adherence in elderly patients with type 2 diabetes	Religious coping with social support, religiosity, physical dysfunction	Since type 2 diabetes is a significant public health concern, especially in the elderly, religion can positively affect their health‐related quality of life (HRQoL) through factors such as religious coping with social support. The effect of religiosity on medication adherence and HRQoL through mediators such as religious coping with social support improves adherence to treatment and quality of life
43	Uchmanowicz et al. [85]	2019	Poland	Conducting a systematic review and meta‐analysis on self‐reported medication adherence and its determinants in hypertensive patients aged 60 and above	Socioeconomic status, unemployment, and retirement, the doctor's opinion about the number and frequency of doses of prescribed drugs, factors related to the disease, drug, and treatment of the person, and duration of the disease	Medication adherence in older people with hypertension is related to age, socioeconomic status, and disease‐ and treatment‐related factors. Thus, older age, retirement, unemployment, blood pressure duration of more than 10 years, and fewer prescribed medications are among the essential factors of higher adherence in the elderly compared to younger people
44	O'Connor et al. [59]	2019	USA	Evaluating how structural and functional support affects medication adherence in older US adults with asthma	Social support, structural support, functional support	By examining the relationship between social support (structural and functional) and medication adherence among older people with asthma, it was proven that receiving frequent functional support in medication management is linked to poor adherence to asthma control medications
45	Yap et al. [69]	2016	Singapore	Investigating factors and strategies to enhance medication adherence in elderly populations	Socioeconomic status, the role of care providers and treatment staff, the role of health care systems, factors related to the disease, medication, and individual treatment.	Factors such as patient, medicine, health care providers, health care system, and socioeconomic factors are considered effective factors in medication adherence
46	Erdem Sultanoğlu et al. [102]	2021	Turkey	Evaluating the relationship between physical function, medication adherence, and quality of life in elderly with rheumatic diseases	Functional disorder, quality of life	Physical performance and quality of life are weaker in older adults. Physical dysfunction compromises medication adherence
47	Corsonello et al. [91]	2010	Italy	Analyzing how comorbidities affect medication adherence and achievement of therapeutic goals	Multiple chronic diseases, comorbidities	The difficulty in rationally prescribing medicine for elderly patients with multiple chronic diseases causes diminished life expectancy and poor medication adherence
48	Vinluan et al. [57]	2015	USA	Evaluating the impact of pharmacist‐led discharge counseling on medication adherence among elderly with heart disease	Counseling by pharmacists	The study results indicate the positive effect of pharmacist counseling on improving medication adherence in patients and lowering the re‐hospitalization rate in patients with heart diseases in the first month after discharge
49	Liu et al. [86]	2017	China	Creating strategies to enhance medication adherence among the elderly in China	Use of new technologies, aspects of healthcare, cognitive impairment, behavioral factors	According to the results, the effect of cognitive factors and behavioral factors of the elderly and aspects of health care and treatment on medication adherence. Since many seniors use smartphones as a means of communication, service delivery can be well based on a program with functions to promote adherence, such as providing medication and health care knowledge, emphasizing the importance of adherence to enhance awareness, helping the patient in managing the drug information and the process of taking the drug, monitoring the health status so that the feedback of the drug effect is well implemented. Side products, such as instruction labels with written information and QR codes, smart bracelets, and alike, can be designed for good communication between older adults and the service platform
50	Yu et al. [89]	2015	China	Leveraging ubiquitous sensors and mobile social networks to improve medication adherence in elderly care	Use of new technologies	By implementing the Socialized Prompting System (SPS) technology in the elderly care and comprehensive laboratory, use of various sensors such as Radio Frequency Identifier (RFID), pressure, light, and noise sensors, implementing an RFID‐based E‐Cabinet to identify drug consumption activities is possible. The E‐Cabinet can detect new medication (a new bottle), program a new medication schedule, and supervise medication activities (when bottles are removed and returned, which are moved) automatically and unobtrusively. Thus, a social stimulation system can boost medication adherence by continuously monitoring drug consumption activities and joint social encouragement services
51	Komiya et al. [94]	2018	Japan	Identifying factors contributing to polypharmacy in elderly home‐care patients	Polypharmacy	Polypharmacy, often seen in elderly patients, has been associated with several adverse outcomes, including increased risk of potentially inappropriate medications, medication non‐adherence, medication duplication, drug–drug interactions, higher healthcare costs, and adverse drug reactions. A significant correlation between polypharmacy and adverse outcomes among community‐dwelling elderly has also been confirmed. Polypharmacy is very common among older adults with in‐home care
52	Kardas et al. [84]	2021	Poland	Analyzing the prevalence of chronic polypharmacy in community‐dwelling elderly in Poland to identify high‐risk groups	Polypharmacy	Polypharmacy, in turn, is a risk factor for adverse drug reactions, drug–drug interactions, non‐adherence, negative medical outcomes, and extensive use of health care services. The longer the exposure to polypharmacy, the greater the risk of these consequences
53	Bezerra et al. [80]	2022	Brazil	Reviewing the economic impact of pharmaceutical services on patients with multiple medications	Polypharmacy	Polypharmacy is linked to the inappropriate prescription of drugs and, in addition to causing poor adherence to drugs, it also lowers the quality of life, elevates the risk of drug side effects, the length of stay in hospitals, and the rate of re‐hospitalization after discharge, while also causing excessive use of health service resources
54	Gardner [34]	2018	England	Examining drug adherence and symptom management strategies in older populations	Polypharmacy	Inappropriate polypharmacy and poor adherence, especially in older adults, are associated with adverse health outcomes
55	Maffoni et al. [92]	2020	Italy	Conducting a systematic review of qualitative studies on medication adherence experiences in older adults with chronic multimorbidity	Comorbidities	Medication adherence is a multifaceted process complexity, affected by individual, social, and environmental factors in people with morbidity
56	González‐Bueno et al. [99]	2021	Spain	Investigating factors leading to medication non‐adherence in multimorbid and polypharmacy patients in an intermediate care center	Comorbidities, polypharmacy	Examining the factors related to medication non‐adherence in elderly patients with multimorbidity and polypharmacy reveals that these are the most determining factors of non‐adherence
57	Félix and Henriques [70]	2021	Portugal	Analyzing determinants of medication adherence in older individuals with multimorbidity through a cross‐sectional study	Comorbidities, polypharmacy	Non‐adherence to self‐reported medications is expected in the elderly with multimorbidity and polypharmacy
58	Miyazaki et al. [96]	2020	Japan	Exploring the association between self‐reported medication adherence and the use of potentially inappropriate medications in elderly patients	Comorbidities, polypharmacy	Non‐adherence to medications is a potential cause of hospitalization, complications, and mortality in the elderly and grows by polypharmacy. Since older people usually use complementary medications, it leads to a decrease in medication adherence
59	Ligons et al. [56]	2011	USA	Evaluating the usability of telemedicine‐based medication delivery systems for older adults	Polypharmacy	Polypharmacy and medication non‐adherence are expected in the elderly, potentially resulting in medication‐related problems in this age group
60	Mabuchi et al. [95]	2020	Japan	Analyzing polypharmacy trends in elderly Japanese patients using real‐world databases	Polypharmacy	Polypharmacy has recently become a significant issue in medical care due to the increased risk of adverse drug reactions (ADRs) and drug interactions, decreased medication adherence, and increased medical costs
61	Cooney and Pascuzzi [55]	2009	USA	Investigating drug interactions and adherence issues related to polypharmacy in elderly hypertensive patients	Multiple chronic diseases, polypharmacy	Polypharmacy in the elderly is highly prevalent owing to the increased number of aging‐related diseases. Blood pressure is one of the diseases that can be challenging to treat in the elderly due to physiological changes, possible risks of side effects, drug interactions, and diminished medication adherence
62	Gellad et al. [22]	2011	USA	Conducting a systematic review to identify barriers to medication adherence in the elderly beyond cost and regimen complexity	Polypharmacy	Non‐adherence to medication is a common problem among the elderly. The studies identified some potential barriers (i.e., factors associated with non‐adherence), including patient‐related factors such as knowledge about the disease and its complications, health literacy, and cognitive function. Drug‐related factors include side effects, polypharmacy, and other factors, such as the relationship between the patient and the provider as well as various logistical obstacles for drug preparation
63	Bastani et al. [27]	2021	Iran	Applying grounded theory to explore medication adherence among the elderly in a developing country	Health literacy, knowledge about the disease and its complications, polypharmacy, stress, lack of efficient monitoring system and support organizations, market‐oriented behavior of beneficiaries, inappropriate and limited lifestyle	Among the factors of medication non‐adherence among the elderly are doubt, fear of drug side effects, lack of follow‐up of patients by doctors, and the negative influence of others and medical staff. Along medication adherence, the patient's lack of awareness, sufficient education, inappropriate and limited lifestyle, difficult living conditions, and social pressures imposed on people can worsen non‐adherence to medication. It is worth noting that other factors, such as the lack of an efficient monitoring system and support organizations, market‐oriented behavior of beneficiaries, consumer discomfort, consumer stress, and frustration, can also cause non‐compliance. Poor medication adherence is a natural and complex issue for older patients receiving polypharmacy. Additionally, the increase in the number of drugs prescribed during discharge from the hospital is associated with non‐adherence, and a high percentage of patients do not understand the purpose of their drugs
64	Chao and Huang [90]	2016	China	Investigating how geriatric syndromes affect medication adherence in dialysis patients	Doubt, fear of drug side effects, consumption discomfort, stress, disappointment, patient‐doctor relationship, difficult living conditions, social pressures, lack of efficient monitoring system and support organizations, the role of care providers and treatment staff, knowledge about the disease and its complications	Geriatric syndromes (GSs) are highly prevalent in patients with end‐stage renal disease (ESRD) undergoing chronic dialysis, irrespective of age. Studies show the effect of GS on medication non‐adherence in ESRD patients and dialysis patients. GS components mainly include polypharmacy and malnutrition. Therefore, interventions that target factors such as frailty, polypharmacy, and malnutrition in the elderly can potentially improve medication non‐adherence and symptom control in these patients
65	Gimeno‐Gracia et al. [98]	2020	Spain	Analyzing polypharmacy prevalence and pharmacotherapy complexity in elderly Human Immunodeficiency Virus (HIV) patients in Spain	Malnutrition, polypharmacy	Older adults with HIV have a high prevalence of polypharmacy, drug complexity, poor adherence, and drug–drug interactions. For this reason, drug therapy optimization should be a priority for these patients
66	Wang et al. [88]	2021	China	Exploring the burden of polypharmacy among elderly patients with chronic diseases in a Chinese community	Polypharmacy	Preliminary evidence was provided for elderly patients with chronic diseases in China by quantifying the drug burden. Multiple drug burdens may help mitigate drug‐related problems, as some older patients have higher drug burdens. Chinese healthcare providers should primarily assess and highlight such patients and develop relevant intervention strategies to ensure medication adherence and daily medication management of elderly patients with polypharmacy
67	Olesen et al. [100]	2013	Denmark	Investigating the impact of generic substitution on medication adherence in elderly polypharmacy patients	Polypharmacy	Among elderly patients under prescribed polypharmacy, generic substitutes do not negatively affect adherence to long‐term drug treatment. So, there is no apparent reason to avoid generic substitution to improve adherence in such patients
68	Olesen et al. [72]	2014	Portugal	Examining the relationship between over‐the‐counter medication use and adherence in elderly patients on multiple prescriptions	Polypharmacy	Medication adherence is a multifaceted issue affected by various factors. One factor may be the concomitant use of over‐the‐counter (OTC) medications, which is common among elderly patients. Among elderly patients taking multiple medications, a positive relationship is observed between the widespread use of OTC medications and adherence to prescribed medications

3.2. Classification of Factors on Medication Adherence

Factors on medication adherence in the elderly were divided into two categories: “personal” and “external” factors. “Personal factors” included three subcategories: “reducing factors,” “increasing factors,” and “other factors.” “External factors” were also classified as “cultural and socioeconomic factors,” as well as factors related to the “influence of others.” “Decreasing factors” were classified into three subcategories: “forgetfulness in consumption,” “negligence in consumption,” and “disorder in consumption.” “Increasing factors” covered the category of “acceptance of consumption.” On the other hand, “other factors” were put in 10 subcategories of “functional disorder,” “cognitive impairment,” “knowledge factors,” “psychological factors,” “biological factors,” “behavioral factors,” “self‐efficacy,” “factors of person's perception of medication adherence,” “factors related to perception of health status and illness and drug treatment.” The category of “Cultural, social, and economic factors” was divided into five subcategories: “demographic factors,” “race,” “religious coping with social support,” “socioeconomic status,” and “social support.” The external factor of the “influence of others” on medication adherence in the elderly was broken down into “interpersonal, organizational, and social factors” (Figure 3).

3.2.1. Personal Factors on Medication Adherence in the Elderly

Most of the studies performed about personal factors on medication adherence in the elderly included polypharmacy in the category of personal increasing factors (n = 17, 25%), cognitive impairment in the category of personal factors (n = 5, 7.35%), and memory factor in the category of personal reducing factors (n = 3, 4.41%) respectively. Most studies have been related to the factors associated with personal disease, medication, and treatment of mentioned comorbidities (n = 7, 10.29%). In addition, a study related to the factors of a person's perception of medication adherence referred to the perception of health status and illness plus drug treatment (n = 1, 1.47%). Regarding the category of the most important factors of medication adherence, the following were found: self‐efficacy category related to depression (n = 6, 8.82%), the category of biological factors linked to age (n = 7, 10.29%), and the category of knowledge factors pertained to health literacy (n = 7, 10.29%) (Table 3).

TABLE 3.

Frequency distribution of studies related to personal factors on medication adherence in the elderly.

General classification of the series of personal factors on medication adherence (frequency, percentage) (reference[s])	Sub‐categorization of the series of personal factors on medication adherence (frequency, percentage) (reference[s])
Personal reducing factors (n = 1, 1.47%) [29]
Use disorder (n = 1, 1.47%) [29]	Difficulty in hearing (n = 1, 1.47%) [60]. Vision problems (n = 1, 1.47%) [77]
Negligence in consumption (n = 1, 1.47%) [29]
Forgetfulness in consumption (n = 3, 4.41%) [29, 62, 75]	Electronic prescription (n = 1, 1.47%) [62]. Memory (n = 3, 4.41%) [33, 54, 58]. Difficulty in understanding and remembering medication instructions (n = 1, 1.47%) [60]
Personal increasing factors (n = 1, 1.47%) [29]
Acceptance of consumption (n = 1, 1.47%) [29]	Polypharmacy (n = 17, 25%) [22, 27, 32, 34, 55, 56, 60, 70, 72, 80, 84, 88, 94, 96, 98, 99, 100, 104]. Simultaneous use of several non‐prescription drugs (n = 1, 1.47%) [72]
Other personal factors
Functional disorder (n = 2, 2.94%) [11, 102]	Fragility syndrome (n = 1, 1.47%) [82]. Physical limitation (n = 1, 1.47%) [82]
Cognitive impairment (n = 6, 8.82%) [8, 36, 54, 64, 76, 79]	Cognitive decline (n = 1, 1.47%) [103]. Functional cognitive impairment (n = 2, 2.94%) [61, 75]
Knowledge factors (n = 1, 1.47%) [67]	Health literacy (n = 7, 10.29%) [19, 22, 31, 53, 61, 77, 79]. Knowledge about the disease and its complications (n = 2, 2.94%) [22, 27]. Patient education according to health literacy (n = 1, 1.47%) [66]. Functional health literacy (n = 1, 1.47%) [74]. Satisfaction with patient counseling (n = 1, 1.47%) [74]. Status and level of education (n = 2, 2.94%) [11, 74]. People's awareness of the disease and prescription drugs (n = 1, 1.47%) [11]. Sufficient information and explaining drug use (n = 1, 1.47%) [74]. Awareness of drug dosage frequency (n = 1, 1.47%) [74]. Health‐related problems (n = 1, 1.47%) [74]
Psychological factors (n = 1, 1.47%) [67]	Doubt (n = 1, 1.47%) [27]. Fear of drug side effects (n = 1, 1.47%) [90]. Consumption discomfort (n = 1, 1.47%) [90]. Disappointment (n = 1, 1.47%) [90]. Stress (n = 2, 2.94%) [27, 90]
Biological factors (n = 1, 1.47%) [67]	Age (n = 2, 2.94%) [2, 78]. Gender (n = 3, 4.41%) [2, 75, 78]
Behavioral factors (n = 2, 2.94%) [67, 89]	Selected health behaviors (n = 1, 1.47%) [23]. Waist size (n = 1, 1.47%) [23]. BMI (n = 1, 1.47%) [23]. Obesity (n = 1, 1.47%) [23]. Smoking and alcohol use (n = 1, 1.47%) [23]. Physical activity (n = 1, 1.47%) [23]. Malnutrition (n = 1, 1.47%) [90]
Self‐efficacy (n = 1, 1.47%) [76]	Depression (n = 6, 8.82%) [15, 50, 53, 58, 63, 76]. Anxiety (n = 2, 2.94%) [58, 63]
Factors related to a person's perception of medication adherence (n = 1, 1.47%) [10]	Perception of health status and illness and drug treatment (n = 1, 1.47%) [51]. Disease burden (n = 1, 1.47%) [51]. Quality of life (n = 1, 1.47%) [102]. Patient's attitude toward seeking help from professionals (n = 1, 1.47%) [68]. Marriage (n = 1, 1.47%) [68]. Attitudes and beliefs pertained to health and illness (n = 3, 4.41%) [2, 15, 101]
Factors related to the individual's disease, medication, and treatment (n = 3, 4.41%) [67, 69, 85]	Tolerance of drug interactions with drugs (n = 1, 1.47%) [60]. Tolerance of drug interactions with illness (n = 1, 1.47%) [60]. Duration of illness (n = 1, 1.47%) [85]. Lack of access to medical care (n = 1, 1.47%) [73]. Multiple chronic diseases (n = 3, 4.41%) [55, 77, 91]. Long‐term drug use (n = 3, 4.41%) [16, 17, 64]. Side effects of the disease (n = 1, 1.47%) [11]. Comorbidities (n = 7, 10.29%) [2, 70, 82, 91, 92, 96, 99]. Weakness (n = 1, 1.47%) [82]

3.2.2. External Factors on Medication Adherence in the Elderly

Most studies on the cultural, social, and economic factors mentioned economic and social status (n = 8, 11.76%), drug cost, and race (n = 2, 2.94%), respectively. In the category of the influence of others in medication adherence, most of the studies have focused on issues such as interpersonal, organizational, and social factors, the relationship between the patient and the doctor, the doctor's opinion about the number and frequency of doses of prescribed drugs as well as the role of care providers and treatment staff (n = 2, 2.94%) (Table 4).

TABLE 4.

Frequency distribution of studies related to external factors on medication adherence in the elderly.

General classification of the series external factors on medication adherence (frequency, percentage) (reference(s))	Sub‐categorization of the series of external factors on medication adherence (frequency, percentage) (reference(s))
Influence factors of others [29]
Cultural and socioeconomic factors [29]
Social support (n = 2, 2.94%) [53, 59]	Structural support (n = 1, 1.47%) [59]. Functional support (n = 1, 1.47%) [59]. Social isolation and loneliness (n = 1, 1.47%) [87]. Appropriate medical care for the elderly living at home (n = 1, 1.47%) [73]
Socioeconomic status (n = 7, 10.29%) [2, 69, 75, 81, 82, 85, 93]	Unemployment and retirement (n = 1, 1.47%) [85]. Household income (n = 1, 1.47%) [81]. Drug cost (n = 2, 2.94%) [2, 52]. Insurance coverage (n = 2, 2.94%) [2, 52]. Use of new technologies (n = 2, 2.94%) [86, 89]. Difficult living conditions and social pressures (n = 1, 1.47%) [90] Inappropriate and limited lifestyle (n = 1, 1.47%) [27] Lack of efficient monitoring system and support organizations (n = 2, 2.94%) [27, 90]. Market‐oriented behaviors of beneficiaries (n = 1, 1.47%) [27]
Religious coping with social support (n = 1, 1.47%) [65]	Religiosity (n = 1, 1.47%) [65]
Race (n = 2, 2.94%) [2, 53]
Demographic factors (n = 1, 1.47%) [53]
Influence factors of others (n = 1, 1.47%) [29]
Interpersonal, organizational, and social factors (n = 1, 1.47%) [67]	The relationship between the patient and the doctor (n = 2, 2.94%) [2, 29]. The number of patient visits to the doctor (n = 1, 1.47%) [2] The doctor's opinion about the number and frequency of doses of prescribed drugs (n = 2, 2.94%) [2, 85]. Doctor's opinion about the dosage form of medicine (n = 1, 1.47%) [2] Living with spouse or family (n = 1, 1.47%) [11] Role of care providers and treatment staff (n = 2, 2.94%) [27, 69] Role of health care systems (n = 1, 1.47%) [69] Aspects of Healthcare (n = 1, 1.47%) [86]

4. Discussion

This study identified various personal and external factors—such as polypharmacy, socioeconomic status, cognitive impairment, health literacy, age, and depression—which would influence medication adherence among the elderly. As Bastani et al. noted, adherence is a multidisciplinary social issue shaped by multiple underlying factors [27].

Healthcare professionals should consider factors influencing medication adherence in the elderly to offer tailored advice and improve health outcomes together with care quality [6]. Identifying factors affecting medication adherence is essential for enhancing elderly well‐being and improving the healthcare economy [105]. This study found that only 1.47% of articles addressed reducing factors such as consumption disorder and negligence, alongside increasing factors such as medication acceptance (Table 3). Medication adherence in the elderly involves multiple dimensions, requiring attention at all health system levels. As Bastani et al. emphasized, effective adherence depends on scientific planning, targeted interventions, and coordinated efforts across the healthcare system [29].

Forestal et al. highlighted personal factors affecting medication non‐adherence in the elderly, particularly issues with electronic prescriptions. Although electronic prescriptions are a modern tool, they may lead to forgetfulness and failure to submit them to pharmacies, especially under the Medicare Modernization Act, thus reducing initial adherence. As such, special attention is required to support the growing adoption of electronic prescriptions [62]. Park's study emphasizes the critical role of memory in medication adherence among the elderly, highlighting the need for memory‐focused interventions and reminder strategies to enhance medication use [18].

Polypharmacy (26.47%) is a key personal factor affecting medication adherence, particularly among older adults. The increasing number of prescriptions contributes to this growing concern, undermining the effectiveness of medical care. Poor adherence is often linked to a limited understanding of medications. Interventions should aim to simplify regimens, lower pill burden, and clearly explain the purpose of each drug. Addressing this issue requires strategic planning, targeted interventions, and coordinated efforts across all levels of the health system [27]. Wong et al. found that polypharmacy negatively affects medication adherence among the elderly, contributing to treatment failure. Drug errors often arise during administration and follow‐up, highlighting the need for safe medication strategies. Optimizing drug management requires deprescribing inappropriate or low‐value medications, taking the patient conditions and preferences into account, setting treatment goals, and adopting a multidisciplinary approach to prevent side effects as well as ensure safe administration [106]. Tiktin et al. recommend simplifying treatment regimens, improving interactions between healthcare professionals and patients, and offering clinical trials, support, and education to enhance patient outcomes together with medication adherence [107]. Alodhaib et al. emphasize the need for tailored educational programs, patient‐specific counseling, and detailed follow‐up to improve knowledge, outcomes, and quality of life in polypharmacy patients [108]. Mathew et al. have proposed a qualitative consultation approach for addressing adherence issues in polypharmacy, including questioning, education, support training, and motivational interviewing [109].

This study explored attitudes and adherence behaviors toward medication among elderly individuals with long‐term respiratory diseases. It proposes strategies to promote adherence according to the target group's developmental stage and behavioral factors, optimizing health outcomes [104]. The study categorized various personal factors in Figure 2 that either have minimal impact on medication adherence in the elderly or indicate both positive and negative effects. These factors include perceptions of medication adherence (1.47%), disease, medication, and treatment‐related factors (1.47%), self‐efficacy (1.47%), behavioral (2.94%), biological (1.47%), psychological (1.47%), knowledge (1.47%), cognitive impairment (8.82%), and functional disorders (2.94%). Comorbidities (10.29%) and cognitive impairment (8.82%) were identified as key factors linked to disease and treatment. Smaje A. et al. emphasized the challenge of medication adherence in elderly patients, suggesting that medication review models and patient education can enhance adherence, particularly for those with comorbidities and cognitive impairment [5]. Other personal factors, such as an individual's perception of health, illness, and drug treatment (1.47%), also influence medication adherence in the elderly. Park HY et al. highlighted the impact of concerns and attitudes, particularly among elderly individuals living alone, emphasizing the need for further interventional studies to address these factors [75]. Rajpura et al. underscored the role of controlling hypertension in preventing cardiovascular disease and the impact of perceived disease burden on adherence to antihypertensive medications in older adults. They suggest that positive beliefs about medications, views on their necessity, and perceptions of threat would significantly improve adherence behavior [51]. Lau et al. found that fear of seeking healthcare support among married Chinese elderly with arthritis negatively impacts self‐care and medication adherence. They recommended that healthcare professionals tailor practical approaches to enhance self‐care and psychosocial well‐being. Thus, marriage (1.47%) and the patient's attitude toward seeking professional help (1.47%) were identified as key factors influencing medication adherence perception [68]. Aktaş et al. emphasized the high prevalence of chronic diseases in the elderly and the growing need for medication. They recommended supporting positive behaviors and educating the elderly about the use of controlled complementary therapies [101].

FIGURE 2.

Temporal distribution of studies on medication adherence in the elderly.

In the category of factors pertained to “disease, medication, and treatment,” long‐term drug use (4.41%) affects medication adherence in the elderly. Chang et al. suggested improving medication adherence in elderly patients with kidney dysfunction and myocardial infarction [16]. Ivers et al. suggested that long‐term prescription of cardiac prevention drugs upon hospital discharge would ameliorate medication adherence among the elderly [17]. According to Qin et al., strategies should be implemented to improve long‐term medication adherence in elderly heart failure patients, particularly those with comorbidities [64]. Sengstock et al. highlighted the importance of ensuring appropriate medication prescriptions at discharge to improve patient adherence. Interventions should address administrative policies, provider challenges, and patient concerns, starting early in the hospital stay and involving continuous support from primary care physicians as well as cardiologists [60].

In the category of factors linked to disease, medication, and treatment, multiple chronic diseases (4.41%) significantly lower medication adherence, as the complications arising from chronic diseases require a deeper understanding of medication adherence in the elderly. Yap AF et al. emphasized the importance of adherence in managing chronic conditions in older adults [10]. As mentioned, cognitive impairment (8.82%), including functional cognitive impairment (2.94%) and cognitive decline (1.47%), is a significant contributor to medication adherence among the elderly. Mizokami et al. demonstrated that cognitive abilities affect adherence, with non‐adherence linked to cognitive decline, underscoring the importance of screening for elderly patients at pharmacies [103]. Cho et al. stated that cognitive impairment negatively affects medication adherence in hypertensive patients, urging doctors in elderly care to monitor cognitive function, educate patients and caregivers, and implement interventions to optimize cognitive performance [43].

In the self‐efficacy category, depression (8.82%) and anxiety (2.94%) impact medication adherence in the elderly. Gentil et al. found that improving the treatment of depression and anxiety in older adults can enhance adherence to antihypertensive medications and improve healthcare outcomes [63]. The mediating function of self‐efficacy in the association between depression and medication adherence among elderly patients with hypertension underscores the importance for healthcare professionals to emphasize early diagnosis of depression and to pursue additional research to gain a deeper insight into this relationship [76]. Regarding behavioral factors, selected health behaviors (1.47%) such as smoking, alcohol consumption, obesity, body mass index, waist size, and physical activity affect medication adherence among the elderly. Han et al. identified key factors for adherence and emphasized the importance of health promotion programs to support self‐care as well as disease management in the elderly [23].

There are psychological factors that can exacerbate medication non‐adherence such as doubt, fear of side effects, lack of patient knowledge, and inadequate training. Additionally, discomfort, disappointment (1.47%), and stress (2.94%) contribute to non‐adherence. Bastani et al.'s study highlighted that effective management and planning of medication adherence in the elderly require interventions and cooperation at all levels of the healthcare system. Poor adherence can significantly affect clinical outcomes, increase healthcare costs, and even lead to death [27].

In the category of knowledge factors, health literacy (1.47%) is a central factor in medication adherence, influenced by functional health literacy (1.47%). The factors that affect functional health literacy include patient counseling satisfaction, education level, sufficient information about drug use, awareness of drug dosage frequency, and health‐related problems (each by 1.47%). Hussain et al. suggested that healthcare professionals should assess health literacy and medication adherence in elderly patients to enhance communication strategies during counseling, particularly regarding medication guidelines, especially in older women [79]. In the Jin et al. study, pharmacists are advised to evaluate patients' functional health literacy and individual characteristics, as well as to inform and satisfy them during consultations [74]. In this study, household income (1.47%), multiple chronic diseases (4.41%), and vision problems (1.47%) were identified as factors influencing medication adherence among the elderly. Low income (socioeconomic factors), multiple chronic diseases (disease‐related factors), and vision problems were classified under consumption disorder (reducing factors). Song et al. suggested that low health literacy is linked to poor medication adherence in the elderly. Healthcare professionals should use appropriate tools to evaluate health literacy and address factors such as low income, multiple chronic diseases, and vision problems to improve medication adherence [76]. According to Soones et al.'s study, limited health literacy negatively impacts elderly adherence to asthma control medications. Thus, interventions are recommended to improve adherence [61].

The category of external factors in this study included the subcategory of the influence of others as well as cultural and social factors (1.47%). In the influence of others subcategory, interpersonal, organizational, and social factors were identified, including the patient‐doctor relationship, number of visits to the doctor, doctor's opinion on drug dosage form, living with a spouse or family, counseling by pharmacists, the role of caregivers, healthcare system function, and aspects of healthcare (1.47% each), as well as the doctor's opinion on the number and frequency of prescribed doses (2.94%). The frequency of drug dosage is determined by the prescribing doctor and is considered an interpersonal factor. In this regard, Patti et al. found that atrial fibrillation (AF) in older patients increases bleeding events and ischemia risk, highlighting the importance of proper anticoagulant dosing [110]. The cultural and socioeconomic factors category included five main subcategories: social support (2.94%), socioeconomic status (10.29%), religious coping with social support (1.47%), race (2.94%), and demographic factors (1.47%). Regarding social support, appropriate medical care for elderly individuals living at home (1.47%) together with social isolation and loneliness (1.47%) would negatively impact social support. Algameel et al.'s study found that home care for older adults can result in inadequate medical attention, resulting in poor treatment adherence, side effects, and hospitalization. Expanding health insurance coverage for older adults and ensuring a resident nurse as well as regular visits from pharmacists are essential for addressing medication issues [73].

In the socioeconomic status category, the factors affecting medication adherence in the elderly were drug cost and insurance coverage (2.94%). These factors, through their impact on the elderly's socioeconomic status, can give rise to medication non‐adherence [10]. Mojtabai et al. found that high drug costs negatively impact medication adherence, resulting in poor health and increased hospitalization among uninsured or partially insured elderly individuals. To address this, the design of the Medicare Prescription Drug Benefits Act should consider the adherence patterns of expensive drugs for low‐income beneficiaries [52].

This study demonstrated the significant impact of new technologies in health information technology on medication management as well as enhancing medication adherence in patients, particularly the elderly. The use of new technologies (2.94%) has the most significant effect on medication adherence in the elderly compared to other factors, influencing the socioeconomic factors affecting adherence. Liu et al. identified cognitive, behavioral, and healthcare‐related factors as significant contributors to medication non‐adherence in the elderly. Cognitive barriers included a lack of awareness about the importance of adherence, insufficient knowledge about medications, negative attitudes toward drug therapy in spite of general health consciousness, and poor understanding of treatment protocols. Behavioral challenges encompassed forgetfulness, inconsistent attention to dosage and instructions, and variability in how older adults collect health information and engage in treatment decisions. Healthcare‐related factors involved incomplete or unclear recommendations from providers and inconsistencies among care professionals. The authors emphasized that leveraging new technologies—such as smartphone‐based programs, instructional labels, QR codes, and smart wearables—can improve communication, education, and monitoring, ultimately boosting medication adherence in elderly populations [86].

Wu et al. demonstrated that the use of online medication management technologies supports elderly individuals in managing their medications—whether through memory aids, digital tools, or assistance from family members—leading to improved medication adherence [111]. Researchers have introduced various technology‐based interventions—such as monitoring systems, proximity sensors, and computer vision—to enhance medication adherence and correct deviations from prescribed regimens. These include assistive health technologies (AHT), cyber‐physical systems (CPS), and smart technologies such as RFID, NFC, IMU, and IoT. The integration of smart pharmaceutical systems (SPS) in elderly care labs, utilizing RFID and environmental sensors, enables real‐time monitoring and scheduling of medication intake through systems such as the RFID‐based E‐Cabinet, also fostering social engagement and encouragement. Additionally, interpersonal and organizational factors—such as pharmacist counseling (1.47%), doctor‐patient relationships (2.94%), and the involvement of care providers and medical staff (2.94%)—significantly contribute to adherence. According to Vinluan et al., pharmacist counseling effectively reduces re‐hospitalization among heart disease patients, highlighting the value of ongoing communication and support [57].

Emerging technologies hold promise to improve medication adherence. Artificial intelligence (AI) and mobile health (mHealth) applications, such as smart pill dispensers and reminder apps, can customize medication schedules and boost adherence rates [112]. Telepharmacy, as highlighted by Emadi et al., facilitates remote counseling and monitoring, particularly beneficial for the elderly in rural areas [37]. However, digital literacy gaps among older adults and concerns about data privacy are challenges that are yet to be resolved. Thus, solutions may involve user‐friendly interfaces and robust cybersecurity measures to ensure accessibility and trust in these tools.

Our study contributes to the existing knowledge and evidence on medication adherence in the elderly. It highlights the need for more comprehensive as well as personalized interventions and plans to enhance their medication behavior and outcomes. One limitation of our study was that we only searched five databases and employed English keywords, whereby some relevant studies in other languages or sources might have been missed.

5. Conclusion

Overall, polypharmacy was found to be the most crucial factor affecting medication non‐adherence in the elderly, followed by socioeconomic status, cognitive impairment, health literacy, age, and depression. Health systems should prioritize managing polypharmacy through simplified regimens and enhanced patient education. Socioeconomic support, psychological counseling, and improved health infrastructure are also crucial. Leveraging technologies such as AI, mHealth, and tele pharmacy can further strengthen adherence, provided challenges such as digital literacy and privacy are addressed through tailored training and secure platforms.

Author Contributions

Shokofeh Afkhami: conceptualization; investigation; formal analysis; writing – original draft; writing – review and editing. Farkhondeh Asadi: conceptualization; supervision; methodology; formal analysis; investigation; validation; writing – original draft; writing – review and editing. Hassan Emami: conceptualization; supervision; methodology; formal analysis; investigation; validation; writing – original draft; writing – review and editing. Azam Sabahi: conceptualization; investigation; formal analysis; writing – original draft; writing – review and editing.

Funding

The authors have nothing to report.

Ethics Statement

All ethical considerations were observed, such as obtaining written consent, maintaining data confidentiality at all stages, the possibility of excluding at any stage, and optional participation in the study. All procedures were reviewed and approved by the Research Ethics Committee of the Shahid Beheshti University of Medical Sciences (Ethical research code: IR.SBMU.RETECH.REC.1402.066).

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.