Health literacy training for older adults: a systematic review with meta-analysis

Abstract

Introduction

Limited health literacy constitutes a global challenge that particularly affects the older population, compromising the ability to access, understand and use health information. Various intervention strategies have been developed to improve the understanding, processing, assessment, and application of health information, favoring better self-care practices among older people.

Objective

To identify health literacy intervention models and investigate the effects on health outcomes as well as health literacy in older adults.

Methods

A systematic review with meta-analysis was conducted. The protocol was registered in the PROSPERO database (CRD42024524874).

Results

Fifteen of the 18 articles included found an increase in health literacy after the intervention. Heterogeneity was identified among the studies due to the use of various instruments for the assessment of outcomes and different intervention formats. However, most interventions involved multiple meetings and were conducted in groups, encompassing multi-component activities that promoted participation, dialogue, and the exchange of experiences among the participants. Communication and access to health information were the most addressed subjects in the interventions. The results of the meta-analysis of nine articles revealed that the interventions had positive impacts on health literacy both in the comparison between the pre- and post-intervention assessments and the comparison to the control group. Other outcomes were also positively impacted by the health literacy interventions, such as quality of life, health behaviors, self-care, self-efficacy, and depressive symptoms.

Conclusion

Despite the diversity of methods and absence of a standard model, the results indicate that health literacy interventions improve health literacy as well as other aspects of mental and physical health in older people.

Introduction

Health literacy is a multidimensional construct [1] and inadequate health literacy is considered a public health problem [2]. This concept goes beyond simply reading health-related texts. It also involves the cognitive and social skills needed to interpret medication instructions, understand health forms, and follow guidelines [3]. Health literacy was first classified on three distinct levels: functional, which refers to basic reading and writing skills applied to health contexts; interactive, which is characterized by the ability to actively apply received information in different situations; and critical, which involves the ability to reflect on and assess health information as well as understand and influence social and environmental determinants [4]. A more recent model expanded the concept and consider people´s knowledge, motivation and competences to access, understand, appraise, and use health information and healthcare services adequately [5].

Health literacy is an essential factor in the context of aging, contributing to the maintenance of functioning and autonomy to ensure that quality of life and active participation in society are basic premises of healthy aging [6]. The impact of health literacy on the health of older people has been the subject of various studies [7, 8]. Adequate levels of health literacy contribute to better cognitive capacity, greater autonomy, and a greater willingness to practice prevention [8–10].

In contrast, low health literacy, which is more prevalent among older people, [11] is a significant barrier to the promotion of healthy aging, as it affects the ability to understand information necessary for self-care [12] and is directly related to a poorer socioeconomic status, exposure to structural racism, having low social support, and having poorer mental health [8]. Therefore, researchers have developed intervention strategies to improve the understanding and effective use of health information [13]. Interventions focused on health literacy have been conducted with various population groups, including older people (see: [14–18]). The approaches include individual interventions [19], home visits, [20] group activities, [21] and game-based interventions [16]. Such interventions can also be effective at improving other health outcomes, such as self-care, quality of life, [22] memory, caregiver burden [14], blood test parameters (e.g., HbA1c, capillary blood glucose, cholesterol, etc.), and lifestyle habits [23].

Two systematic reviews have been published on the topic [24, 25]. The first included 21 studies but did not directly assess the impact of the interventions on health literacy; instead, it examined various health-related outcomes [25]. The second, which analyzed 34 articles, included participants aged 50 years or older (and not exclusively older adults), and 16 of the studies did not use a tool to assess participants’ health literacy prior to the interventions [24]. It is worth noting that these reviews were not registered in PROSPERO and had not been published at the time the present review was registered. Therefore, there is a gap in the scientific evidence regarding these intervention models and their effects, as the existing data have missing elements, making it difficult to determine the most effective approach to follow.

Therefore, the aim of the present systematic review was to identify health literacy intervention models and investigate the effects on health outcomes as well as health literacy in older adults. Based on this mapping, we intend to offer a critical analysis of the approaches, structures, and outcomes analyzed in order to provide consistent support for researchers, healthcare providers, and administrators in the development and implementation of evidence-based strategies capable of generating positive impacts.

Methods

The present systematic review with meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA Statement) [26]. The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) on March 15th, 2024, and approved on March 26th, 2024 (registration number: CRD42024524874).

Data sources

The LILACS, PsycINFO, PubMed, Scopus, and Web of Science databases were selected for this review. The search was conducted on April 24th, 2025, using the following search terms: “aged”, “education”, “elderly” “health literacy”, “intervention”, “older adult”, and “training” as well as the Boolean operators “AND” and “OR”, combined in the following manner in all five databases: ““health literacy” AND (“education” OR “training” OR “intervention”) AND (“aged” OR “older adult” OR “elderly”)”.

Eligibility criteria

The following eligibility criteria were established by the authors prior to the search of the five databases (i.e., LILACS, PsycINFO, PubMed, Scopus, and Web of Science):

1. Participants must be older people (60 years or older) – in any setting (e.g., hospitals, institutions, community, outpatient clinics);

2. Studies that performed health literacy training and identified effects on health literacy and/or other health outcomes;

3. Quantitative experimental and quasi-experimental studies;

4. Any language;

5. Any year of publication.

The following were excluded: a) gray literature (e.g., books and book chapters, theses, and dissertations); b) reviews; c) comments; d) notes; e) errata; f) literature reviews; g) letters to the editor; h) collections of abstracts; and i) articles that investigated specific health literacy (e.g., mental health, dementia, digital, etc.).

Data extraction

Two reviewers (MAMB and BML) performed the search and data extraction for the Rayyan® online reference manager (https://www.rayyan.ai/), which was developed to assist researchers in conducting systematic reviews [27]. After exporting the data into the reference manager, the authors identified and removed duplicates. Three reviewers (JKSP, MAMB, and BML) then independently analyzed the articles retrieved from the databases by reading the titles and abstracts. Articles for which divergences of opinion occurred in this step (i.e., title and abstract selection) were analyzed by a fourth author (FSO) to make the decision (i.e., inclusion or exclusion) for the next stage (i.e., full-text analysis). Once the title and abstract selection step was completed, four reviewers (FSO, JKSP, MAMB, and BML) independently performed the full-text analysis of the preselected articles.

In this step (i.e., full-text analysis), articles for which questions arose either individually or collectively were presented at an online meeting via Google Meet with all authors to make the final decision. The authors also searched the reference lists of the selected articles, which is one of the recommendations of the PRISMA Statement [26]. This step was performed to minimize the non-inclusion of potentially relevant articles [28]. To avoid selection bias, all steps were performed independently [29]. Pre-established strategies were adopted to gain access to the full text of all selected articles, such as email requests to the corresponding author, requests to authors via ResearchGate, and voluntary collaboration from researchers of other countries. Figure 1 displays the details of the selection process leading to the final inclusion of 18 articles.

Fig. 1.

Selection of eligible articles presented in PRISMA flowchart

Synthesis of data

Data were extracted from the articles included in this review by two authors (JKSP and BML), organized on a Microsoft Excel spreadsheet, and presented in tables in the “Results” section: i) first author; ii) year of publication; iii) country in which the study was conducted; iv) setting (e.g., community, hospital, nursing home, etc.); v) study design; vi) number of participants (overall and in each group, when applicable); vii) specific criteria for inclusion in the study (e.g., chronic conditions, high blood pressure, etc.); viii) sex of the participants; ix) age of the participants (mean and standard deviation or category with the highest percentage); x) number of intervention meetings; xi) duration of meetings; xii) type of intervention; xiii) topic addressed in the intervention; xiv) health literacy assessment instrument; xv) instrument(s) for assessing other outcome(s); xvi) follow-up; xvii) main results. Articles with missing information were included provided that they met the inclusion criteria.

Quality appraisal

The methodological quality of the studies was appraised using the checklists of the Joanna Briggs Institute for quasi-experimental studies (available at: https://jbi.global/sites/default/files/2020-07/Checklist_for_Quasi-Experimental_Appraisal_Tool.pdf) and randomized controlled trials (available at: https://jbi.global/sites/default/files/2020-08/Checklist_for_RCTs.pdf) [30]. The classification used in other reviews of clinical trials [31] was adopted: low, moderate, and high quality. Low risk of bias/high quality was attributed to studies with ‘Yes’ answers on more than 70% of the items; moderate risk of bias/moderate quality was attributed when the ‘Yes’ rate was between 50 and 69%; and high risk of bias/low quality was attributed when the ‘Yes’ rate was equal to or less than 49%. It should be noted that each item in the checklists comprises four response categories (i.e., Yes, No, Unclear, and Not Applicable).

Meta-analysis

Before performing the meta-analysis, we conducted a qualitative assessment of the selected articles. Those that offered numerical data (i.e., mean and standard deviation) on pre- and post-intervention health literacy and the comparison between the intervention and control groups were included in the meta-analysis (i.e., nine articles). The Jamovi software (version 2.6.44) was used for this purpose. Two meta-analyses were conducted using the standardized mean difference (SMD) of health literacy scores between groups (i.e., pre- vs. post-intervention; intervention vs. control). The effect size was classified as low (0.20), medium (0.50), or high (0.80). Heterogeneity was assessed using the DerSimonian-Laird estimator [32]. The Q test was then performed and the I² index was determined. Possible outliers in the studies selected for meta-analyses were also analyzed. Publication bias was investigated using funnel plots and the extent of asymmetry was quantitatively examined using Egger’s and Begg’s tests [33, 34].

Results

Selection and presentation of studies

The search of the databases led to the retrieval of 16,378 records. After discarding duplicates, 9,340 remained for the analysis of titles and abstracts. Following this step, 126 articles were selected for full-text reading. However, the researchers were unable to obtain one of the articles even when using the pre-established strategies. In the end, 17 articles were selected for data collection and one was included after searching the reference lists of the selected articles, totaling a sample of 18 articles. The data extracted from the articles are summarized below.

Quality of studies

Among the eight experimental studies, only one had a low risk of bias and high quality, five had a moderate risk of bias, and two had a high risk of bias, with low quality (46.2% and 30.8%, respectively). Among the 10 quasi-experimental studies, one had fulfilled 100% of the quality appraisal items [35] and another seven achieved more than 70%, indicating low risk of bias and high quality. Two studies had a moderate risk of bias and none had a high risk of bias/low quality. The scores of the studies and the items that comprise the quality appraisal instrument are presented in Table 1.

Table 1.

Risk of bias of studies included in present systematic review [19–21, 35–49].

Experimental studies: Q1—Was true randomization used for assignment of participants to treatment groups? Q2- Was allocation to treatment groups concealed? Q3- Were treatment groups similar at the baseline? Q4- Were participants blind to treatment assignment? Q5- Were those delivering treatment blind to treatment assignment? Q6- Were outcomes assessors blind to treatment assignment? Q7- Were treatment groups treated identically other than the intervention of interest? Q8- Was follow-up complete and if not, were differences between groups in terms of their follow-up adequately described and analyzed? Q9- Were participants analyzed in the groups to which they were randomized? Q10- Were outcomes measured in the same way for treatment groups? Q11- Were outcomes measured in a reliable way? Q12- Was appropriate statistical analysis used? Q13- Was the trial design appropriate, and any deviations from the standard RCT design (individual randomization, parallel groups) accounted for in the conduct and analysis of the trial? Quasi-experimental studies: Q1- Is it clear in the study what is the ‘cause’ and what is the ‘effect’ (i.e. there is no confusion about which variable comes first)? Q2- Were the participants included in any similar comparisons? 3- Were the participants included in any comparisons receiving similar treatment/care, other than the exposure or intervention of interest? Q4- Was there a control group? Q5- Were there multiple measurements of the outcome both pre and post the intervention/exposure? Q6- Was follow up complete and if not, were differences between groups in terms of their follow up adequately described and analyzed? Q7- Were the outcomes of participants included in any comparisons measured in the same way? Q8- Were outcomes measured in a reliable way? 9- Was appropriate statistical analysis used?  : Yes. : No. : Unclear

Characteristics of studies

Among the 18 articles that investigated the effects of health literacy interventions in older adults, the oldest was published in 2014 and the most recent was published in 2025. The years with the most publications were 2021 and 2022, with four articles (22.2%) each. The studies were developed in several countries, the most frequent being Thailand, with seven publications (38.9%), followed by Brazil and China, with three publications (16.7%) each, then Spain, the United States, Iran, Japan, and Germany, with one article (5.6%) each.

The studies selected for the present systematic review were experimental (44.4%) and quasi-experimental (55.6%). The sample size ranged from 21 to 369 older people, with 72.2% of the articles dividing the sample into an intervention group and a control group, whereas the rest (27.8%) involved an intervention group alone. Women predominated in 77.8% of the studies.

Regarding the age of the participants, 77.8% of the studies described a mean or median, which ranged from 65.9 to 81.7 years. In the four studies (22.2%) that provided this information in percentage, the majority of the sample was between 60 and 70 years of age, ranging from 63.0% in the control group of the study conducted by Visuttranukul et al. [48] to 81.0% in the study conducted by Serbim et al. [47]. In terms of setting, the participants were recruited from the community, healthcare services (e.g., hospital) and others, with a predominance of the community (33.3% total, 22.2% without distinction and 11.1% rural communities). A total of 38.9% of the studies selected older adults with some chronic condition (e.g., diabetes, hypertension) for the interventions. Table 2 displays the characteristics of the studies included in the present review. Schooling level was described in 16 articles. Most studies had participants with a low level of schooling, such as 91.7% and 90.0% of the sample with only a primary school education.

Table 2.

Characteristics of 18 studies included in present systematic review

Reference, year	Country	Design	N (IG; CG)	Sex, female (%)	Age Mean (SD)	Education	Setting	Specificities of sample
Blancafort Alias et al. [21]	Spain	RCT	360 (194; 164)	81.4	73.6 (6.9)	82.2% without or only primary studies	Primary care centers in low-income neighborhoods	Fair or poor self-rated health
Chantharacherd et al. [43]	Thailand	QE	30	80	73.3%—60–69	60.0% high school	Community senior club	-
Doi-Kanno et al. [19]	Brazil	QE	21	45.9	75.3 (5.6)	-	Medical services	Japanese-Brazilians
Kakahthum et al. [36]	Thailand	RCT	60 (30; 30)	48.3	IG: 65.1 (2.8) CG: 64.9 (3.0)	IG: 86.7% CG: 93.3% Primary school	Primary care clinic	Type II DM and hypertension
Kim et al. [37]	USA	RCT	369 (185; 184)	69.9	70.9 (5.3)	Mean (SD) 11.2 (4.3) years	Korean American churches and senior centers	Korean American; high blood pressure
Leung et al. [20]	China	QE	165	60.6	81.7 (6.5)	47.3% No formal education	Community	2 or more drugs/day
Liu et al. [38]	China	RCT	260 (126; 134)	49.2	IG: 79.2 (8.8) CG: 79.1 (9.2)	IG: 48% CG: 56% Primary and below	Nursing homes	-
Ongkulna et al. [39]	Thailand	RCT	100 (50; 50)	68	IG: 68.0 (6.3) CG: 68.2 (5.1)	90% Primary school	Hospitals	Primary hypertension
Pooseesod et al. [44]	Thailand	QE	60	56.7	69.4 (6.3)	91.7% Primary school	Community	-
Seangpraw et al. [45]	Thailand	QE	128 (64; 64)	57	65.9 (5.4)	50.8% No formal education	Rural communities	At risk for diabetes
Serbim et al. [46]	Brazil	QE	42 (13; 15)	IG: 66.7; CG: 76.2	IG: 71.4% CG: 81.0%—60–69 years	Median 4 years	Primary health care unit	-
Serbim et al. [47]	Brazil	QE	42 (13; 15)	IG: 66.7; CG: 76.2	IG: 71.4% CG: 81.0%—60–69 years	Median 4 years	Primary health care unit	-
Srisaknok et al. [40]	Thailand	RCT	90 (45; 45)	IG: 53.3; CG: 53.3	IG: 69.9 (6.1) CG: 67.3 (6.4)	IG: 28.9% CG: 57.8% Grade 6, primary school	Community senior schools	-
Taherian et al. [35]	Iran	QE	86 (35; 41)	IG: 53.7; CG: 57.9	66.4 (4.2)	IG: 51.4% CG: 61.0%  < high school graduate	Health-care centers	-
Uemura et al. [41]	Japan	RCT	84 (42; 42)	72.2	IG: 72.1 (4.6) CG: 71.6 (4.4)	Mean (SD) IG: 12.9 (1.8) CG: 12.9 (1.9)	Rural communities	-
Visuttranukul et al. [48]	Thailand	QE	92 (46; 46)	IG: 98.5; CG: 96.2	IG: 63.0% CG: 67.0%—60–70 years	IG: 84.2% CG: 80.9% Primary education	Community	-
Zastrow et al. [49]	Germany	QE	183	79.2	69.1 (6.7)	42.1% Secondary/elementary school	Community	-
Zhang et al. [42]	China	RCT	126 (63; 63)	45.2	IG: 68.7 (5.4) CG: 69.0 (5.2)	-	Hospital	Chronic diseases

IG Intervention group, CG Control Group, SD Standard deviation, RCT Randomized controlled trial, QE Quasi-experimental

Health literacy interventions

With regards to the health literacy interventions carried out with older people, the number of meetings ranged from one to 24, with an average of 9.8 meetings. Two articles did not report the number of meetings. The duration of the meetings ranged from 20 to 240 min, with an average of 100.7 min. Two studies did not report the duration of the meetings. A total of 44.4% of the studies had follow-up assessments, which took place between three weeks and 18 months after the intervention, with an average of 7.2 months. This information is detailed in Table 3.

Table 3.

Characteristics and outcomes of interventions

Reference, year	Meetings	Duration of meeting (minutes)	Follow-up	Health literacy instruments	Other instruments	Health literacy outcome	Other health outcomes
Blancafort Alias et al. [21]	12	120	9 months	HLS-EU-16	SF-12, EQ-5D, ASA-R, Social Resources Inventory in Older Adults, Este II Subjective Social Participation Index, WEMWBS, 11-item De Jong Gierveld Loneliness Scale, GDS-5	↑ HL	↑ mental domain QoL ↓ loneliness ↓ depressive symptoms ↑ self-perception of health
Chantharacherd et al. [43]	3	180	-	Test of health information literacy (self- developed)	-	↑ HL	-
Doi-Kanno et al. [19]	1	20	12 months	HLS-14	General Self-efficacy Scale, VAS (satisfaction with the health guide and subjective health status)	NS	↓ Satisfaction with health guide and subjective health (post-intervention x follow-up)
Kakahthum et al. [36]	3	90	3 weeks	Health Literacy Scale for Thai version by Chiangkhong et al.,	Self-care behavior scale	↑ HL	↑ self-care
Kim et al. [37]	6	120	18 months	HBP health literacy scale	8-item Hill-Bone Medication Adherence scale, 26-item HBP knowledge questionnaire, HBP self-efficacy, PHQ-9	↑ HL	↑ self-efficacy ↑ treatment adherence ↑ knowledge of BPH ↓ depressive symptoms
Leung et al. [20]	4	60	12 months	CHLCC	GDS, MoCA, MCKS	↑ HL	↑ treatment adherence
Liu et al. [38]	3	40	-	Chinese Citizen Health Literacy Questionnaire	-	↑ HL	-
Ongkulna et al. [39]	6	120	1–3 months	HLS-14	HSMSES; SMBS	↑ HL	↑ self-efficacy ↑ self-management behavior
Pooseesod et al. [44]	6	180	-	Health Literacy Test developed by the Health Education Division, Ministry of Public Health, Thailand	3E2S health behaviors test developed by Health Education Division, Ministry of Public Health, Thailand	↑ HL	↑ 3E2S health behaviors
Seangpraw et al. [45]	12	180–240	3 months	Health-Literacy Questions	Self-efficacy and health behavior related to diabetes, blood glucose and glycated hemoglobin, and renal function control	↑ HL	↑ self-efficacy ↑ health behaviors
Serbim et al. [46]	20	90	-	SAHLPA-18	Health behaviors (vaccines, physical activity, food choices, smoking, and alcohol use)	NS	↑ vaccination rate
Serbim et al. [47]	20	90	-	SAHLPA-18	Health behaviors (vaccines, physical activity, food choices, smoking, and alcohol use)	NS	↑ vaccination rate ↑ At least 3 meals/day
Srisaknok et al. [40]	-	100	1 month	Health literacy questionnaire developed by researcher	-	↑ HL	-
Taherian et al. [35]	12	120	-	Health literacy for Iranian adults questionnaire	SF‐12, Onyx and Bullen social capital questionnaire, questionnaire for assessing the self‑care ability of the elderly	↑ HL	↑ QoL ↑ self-care ↑ social capital
Uemura et al. [41]	24	90	-	HLS-14 HLS-EU-Q16	Wechsler Adult Intelligence Scale-III, verbal fluency, digit span forward and backward tests, Scenery Picture Memory Test, Grip strength, 5-m walking test, TUG, triaxial accelerometer (daily physical activity), dietary habit	↑ HL	↑ cognitive function (category: verbal fluency, memory) ↑ physical function (gait speed, balance) ↑ amount of physical activity ↑ diet variety
Visuttranukul et al. [48]	5	90	-	Health Literacy and Behavior Assessment Form	WHOQOL- BREF-THAI	↑ HL	↑ QoL ↑ health behaviors
Zastrow et al. [49]	19	-	-	HLS-EU-Q16	-	↑ HL	-
Zhang et al. [42]	-	-	-	Health Literacy Scale for Patients with Chronic Diseases	Knowledge cognition, ESCA, CD-RISC, HAMD, Quality of Life Scale for Elderly Patients with Chronic Diseases, blood glucose and blood pressure levels	↑ HL	↑ knowledge cognition ↑ self-care ↑ resilience ↓ depressive symptoms ↑ physical health ↑ QoL

HL Health Literacy, HLS-EU-16 European Health Literacy Scale—16 questions, SF-12 12-item Short Form Survey, SAHLPA Short Assessment of Health Literacy for Portuguese Speaking Adults, EQ-5D Euroqol 5 Dimensions, ASA-R Appraisal of Self-Care Agency Scale, WEMWBS Warwick-Edinburgh Mental Wellbeing Scale, GDS Geriatric Depression Scale, QoL Quality of Life, HLS-14 Health Literacy Scale, VAS visual analog scale, HBP high blood pressure, PHQ-9 Patient Health Questionnaire, CHLCC Chinese Health Literacy Scale for Chronic Care, NS Not significant, 3E2S eating, emotion, exercise, stop smoking, and stop drinking, MoCA Montreal Cognitive Assessment, MCKS Medication Compliance, Knowledges and Storage, HSMSES Hypertensive Self-Management Self-Efficacy Scale, SMBS Self-Management Behavior Scale, SF‐12 The Iranian version of short‐form health survey‐12, WHOQOL- BREF-THAI WHO Quality of Life Assessment Form, ESCA Exercise of Self-Care Agency Scale, CD-RISC Connor-Davidson Resilience Scale, HAMD Hamilton Depression Scale, TUG Timed Up and Go Test

↑: Increase. ↓: Decrease

Most interventions took place in groups (66.6%). A total of 11.1% were mixed (i.e., group and individual telephone calls, group and home visits, etc.). The study conducted by Pooseesod et al. [44] involved six 180-min meetings as well as weekly informal dialogues and monthly home visits over 22 weeks.

The approaches used in the health literacy interventions varied but were generally composed of multicomponent activities that promoted participation, dialogue, and the exchange of experiences among the participants. Games, presentations, practical activities, demonstrations, videos and pictures, quiz games, workshops, dynamics, simulations, and case studies were also used. Some studies held meetings in outdoor spaces. The “teach back” method was mentioned in two articles and the “Ask Me 3” method was described in one. Four articles (22.2%) reported delivering a manual/booklet to the participants and one investigation proposed an individual follow-up diary. The use of a leaflet was described in the two studies with an individual approach, one of which also included verbal advice and comic books. Data on the intervention format and approaches are displayed Table 4.

Table 4.

Content of health literacy interventions

Reference	Topics addressed in intervention
	Physical activity	Self-care/self-management	Emotional health	Healthy eating	Social relationships	Community participation	Autonomy	Communication/Access to health information	Medications	Health decision making	Specific health conditions	Falls	Others*
Blancafort Alias et al. [21]	✔	✔	✔	✔	✔	✔	✔	✔
Chantharacherd et al. [43]								✔
Doi-Kanno et al. [19]				✔							✔		✔
Kakahthum et al. [36]	✔		✔	✔				✔	✔	✔	✔
Kim et al. [37]	✔			✔				✔	✔	✔	✔
Leung et al. [20]									✔
Liu et al. [38]			✔	✔				✔	✔				✔
Ongkulna et al. [39]	✔	✔	✔	✔					✔		✔
Pooseesod et al. [44]		✔						✔		✔			✔
Seangpraw et al. [45]	✔	✔	✔	✔				✔	✔	✔	✔
Serbim et al. [46]	✔	✔	✔	✔	✔			✔	✔		✔	✔	✔
Serbim et al. [47]	✔	✔	✔	✔	✔			✔	✔		✔	✔	✔
Srisaknok et al. [40]		✔						✔	✔	✔			✔
Taherian et al. [35]	✔	✔	✔	✔	✔	✔	✔	✔
Uemura et al. [41]	✔			✔				✔				✔
Visuttranukul et al. [48]	✔	✔	✔		✔			✔		✔		✔
Zastrow et al. [49]	✔	✔	✔	✔		✔		✔
Zhang et al. [42]	✔	✔		✔					✔		✔		✔

^* Topics that could not be grouped and were cited by one study each

The content of the health literacy interventions varied. The most frequently addressed topics were communication and access to health information (77.8%), followed by healthy eating (72.2%), physical activity (66.7%), self-care/self-management (61.1%), emotional health (55.5%), and use of medications (55.5%). Other topics included specific health conditions (44.4%), health-related decision making (33.3%), social relationships (27.8%), falls (22.2%), community participation (11.1%), and autonomy (11.1%). Seven articles (38.9%) addressed topics that could not be grouped and were mentioned separately in each study. This information is displayed in Table 5.

Table 5.

Format and approaches used in health literacy interventions

Reference	Intervention format	Approaches used
Blancafort Alias et al. [21]	Group	Multi-component, participatory activities to promote empowerment 3 meetings in outdoor spaces
Chantharacherd et al. [43]	Group	Participatory activities, considering the knowledge and experience of the participants; games, presentations, practical activities, group discussions, brainstorming
Doi-Kanno et al. [19]	Individual	Leaflet
Kakahthum et al. [36]	Group	Presentations, manual distribution, demonstrations, use of videos, pictures, quizzes "Ask me 3" and "teach back" methods
Kim et al. [37]	Group + individual phone call	Educational sessions and behavioral education Home blood pressure monitoring Monthly counseling calls
Leung et al. [20]	Individual	Verbal advice Leaflets Comic books
Liu et al. [38]	Group	Teach-back method
Ongkulna et al. [39]	Group	Geragogy and transformative learning Booklet
Pooseesod et al. [44]	Group + follow-up home visits	Exchange of knowledge and experiences, dialogue among participants. Handbook distribution Home follow-up visits
Seangpraw et al. [45]	Group + individual follow-up diary	Presentations, discussions, and exchange of experiences Handbook distribution
Serbim et al. [46]	Group	Videos, workshops, games, group activities, exhibitions and discussions, printed materials, and illustrations Visit to a senior citizens’ association
Serbim et al. [47]	Group	Videos, workshops, games, group activities, exhibitions and discussions, printed materials, and illustrations Visit to a senior citizens’ association
Srisaknok et al. [40]	Group	Lectures, exchange of experiences and knowledge, reflections, case studies, practical exercises and interactive summaries, leaflets, posters, video clips
Taherian et al. [35]	Group	Multi-component, photos, interactions, discussions, tutorials, stories, video 3 meetings in outdoor spaces
Uemura et al. [41]	Group	Learning (homework), group discussion, self-planning and implementation of health promotion in daily life
Visuttranukul et al. [48]	Group	Leaflets, yoga activities, games and recreational activities, presentations, simulations, and case studies
Zastrow et al. [49]	Group	Participatory approach and discussions, exchange of experiences
Zhang et al. [42]	Group + individual + post-discharge follow-up at home (in-person or telemedicine)	Personalized activities Written materials

Health literacy assessment instruments

Various instruments were used for the assessment of health literacy in older adults (Table 3). The most common were the European Health Literacy Survey Questionnaire 16-items (HLS-EU-16) and the Health Literacy Scale 14-items (HLS-14), corresponding to 16.7% of the surveys each, followed by the Short Assessment of Health Literacy for Portuguese-Speaking Adults (SAHLPA-18), accounting for 11.1%. Other investigations used other instruments, such as the Health Literacy Scale for Thai Version, HPB Health Literacy Scale, CHLCC, Chinese Citizen Health Literacy Questionnaire, Health Literacy Test developed by the Health Education Division, Ministry of Public Health, Thailand, Health-Literacy Questions, Health Literacy for Iranian Adults Questionnaire, Health Literacy and Behavior Assessment Form and Health Literacy Scale for Patients with Chronic Diseases. Chantharacherd et al. [43] and Srisaknok et al. [40] developed their own instrument for assessing health literacy.

Assessment instruments for other health outcomes

Four studies did not use instruments to measure other outcomes. Among the articles that used instruments, various aspects were addressed. The most common was quality of life, which was assessed in four studies, followed by self-care and self-efficacy, in three studies each. Other outcomes were depressive symptoms, cognitive performance, loneliness, adherence to medication, health behaviors (e.g., vaccination, physical activity, dietary habits, smoking, and alcohol use), social capital, physical capacity (e.g., gait speed and balance), and resilience. Detailed information on the instruments is displayed in Table 3.

Effect of health literacy intervention

Among the 18 articles included in this review, three (16.7%) found no increase in health literacy after the intervention. Of these, Doi-Kanno et al. [19] carried out the intervention individually, with a 20-min meeting; and Serbim et al. [46, 47] carried out the same intervention in both studies, with twenty 90-min meetings. All other articles identified improved health literacy after the intervention.

Nine articles described pre- and post-intervention health literacy scores and were selected for meta-analysis (Fig. 2a). Seven articles that compared the intervention vs. control groups were also selected (Fig. 2b). The interventions were effective at enhancing health literacy in the comparison of pre- and post-intervention scores (SMD = 1.49, p < 0.001; 95% CI: 0.61–2.36; I² = 97.4%; p < 0.001). The intervention and control groups were compared in terms of health literacy scores in a second meta-analysis (SMD = 1.52, p < 0.001; 95% CI: 0.74–2.29; I² = 96.5%; p < 0.001), in which the findings support the previous result (i.e., pre- vs. post-intervention comparison). Heterogeneity was high (I² = 97.4% and I² = 96.5%, respectively). This high heterogeneity in the meta-analyses may be explained both by the different measures used to assess health literacy and by variations in intervention models (e.g., duration and content). The risk of publication bias was assessed using Egger’s and Begg’s tests. The pre- vs. post-intervention analysis revealed a p-value of > 0.05 (Fig. 3a), indicating no risk of publication bias. In the intervention vs. control group meta-analysis, Begg’s test had a p-value of > 0.05, whereas Egger’s test had a p-value of < 0.05, indicating publication bias, as shown in Fig. 3b. The presence of publication bias, as indicated by Egger’s test, suggests that the pooled effect size may overestimate the true intervention effect, reinforcing the need for cautious interpretation of the meta-analytic findings.

Fig. 2.

Forest plot of health literacy level in older people assessed pre- and post-intervention (a) and intervention vs. control (b)

Fig. 3.

Funnel plot to identify publication bias in publications that assessed pre- and post-intervention (a) and intervention vs. control (b)

Among the eight articles that performed follow-up, four identified improved health literacy at the follow-up assessment. The follow-up time in these studies was three weeks, one month and three months, three months, and 18 months (longest follow-up time).

Effect of intervention on other health outcomes

As stated above, 14 studies investigated the effect of health literacy interventions on other health outcomes. Quality of life improved in 16.7% of the studies included in this review. Overall health behaviors also improved in 16.7% of the studies. Results were also reported on health-promoting behaviors. Thus, 11.1% of articles found an improvement in the vaccination rate, 5.6% in dietary variety, 5.6% reporting an increase in participants who ate at least three meals a day, and 5.6% reporting an increase in physical activity. Self-perceived health improved in 11.1% of the studies (Table 3).

A total of 16.7% of the studies identified an increase in self-care, 16.7% identified an increase in self-efficacy, and 5.6% in self-management behavior. A reduction in depressive symptoms was reported in 16.7% of the studies. One reported a reduction in loneliness and an increase in the score of the mental health domain of quality of life. One reported an increase in resilience. Improvements were also identified in cognitive function and knowledge cognition. Moreover, 11.1% studies reported improved health/physical function, 11.1% reported identified greater adherence to medication/treatment, 5.6% reported an increase in social capital, and 5.6% reported better knowledge of arterial hypertension.

Discussion

This systematic review with meta-analysis was conducted to investigate the effects of health literacy interventions on health literacy and other health-related outcomes in older people. Heterogeneity was found among the studies included, especially regarding pre- and post-intervention assessments as well as the structure of the control and intervention groups. However, the meta-analyses revealed that the interventions improved health literacy indicators. Through the analysis, we also identified that such interventions can exert a positive impact on other aspects related to mental and physical health.

The improvement in health literacy following the interventions is similar to findings described in previous studies involving other populations (e.g., adults) [50–52]. A health literacy intervention conducted with 120 adults with uncontrolled hypertension to improve adherence to medication found that the intervention improved health literacy and used important aspects of literacy (e.g., reading hospital materials) [53]. A possible explanation for the findings of this meta-analysis is the content covered in the interventions, which focused on health literacy.

As stated above, health literacy encompasses aspects related to the individual management of health-related information and it is not limited to functional health literacy, nor focus only in the person, but also in the context. According to Sørensen et al., [13] and Nutbeam [54], interventions that address aspects other than the basic understanding of health information (e.g., communicative and critical literacy) exert a more significant and lasting impact on health literacy. In contrast, interventions that address only one dimension may have limited effects, as essential skills for accessing the healthcare system and decision making may not be developed [25]. In the present review, eight of the nine articles included in the meta-analysis addressed content that encompassed multidimensional aspects of health literacy, which may explain the positive results.

Some studies were not included in the meta-analysis due to a lack of necessary information. However, these studies also reported positive results and addressed multidimensional aspects of the outcome variable (i.e., health literacy) in their interventions [35, 43, 48]. Chantharacher et al. [43] developed a training program based on inter-managerial and participatory learning, addressing multidimensional aspects of health literacy, which resulted in an effective improvement. Similar results were identified in the study by Taherian et al. [35] and are also identified in investigations conducted with other populations (e.g., children, adolescents) [55, 56]. Therefore, the importance of addressing the multidimensionality of health literacy is clear, irrespective of the target population.

Another important aspect concerns the absence of a comparison group (i.e., control group) in some studies. The absence of a control group is considered a significant methodological limitation, as it compromises the ability to attribute the observed effects to the intervention [57]. The use of a control group is essential in intervention studies to ensure the validity of the results and enable an accurate assessment of the effect of the intervention [58]. To support the results of the first meta-analysis (i.e., pre- and post-intervention comparison), a second meta-analysis was conducted comparing the control and intervention groups, the results of which also revealed a significant improvement in the level of health literacy of the participants.

The literature has demonstrated that older adults with adequate health literacy have better health outcomes, including mental, physical, and cognitive aspects [8]. In this review, in addition to the positive impact on health literacy indicators, the interventions also led to improvements in other health-related aspects, such as quality of life, health behaviors, self-care, self-efficacy, and depressive symptoms. A possible explanation for this improvement resides in the enhanced ability to understand, process, and apply health information, which facilitates the adoption of healthy behaviors [59].

According to Nutbeam [54], health literacy serves not only as an individual resource, but also as a social determinant of health, with the potential to reduce inequalities and improve the self-management of chronic conditions. A systematic review conducted by Lam et al. [60] found that health literacy programs with an emphasis on promoting physical activity in middle-aged adults with type 2 diabetes mellitus also promoted improvements in self-efficacy and knowledge related to self-management of the disease. Among the studies included in the meta-analysis, only the article by Liu et al. [38] found no impact on other aspects assessed besides health literacy.

Even though the results were satisfactory, it is important to discuss the duration of the interventions, on which no consensus is found in the scientific literature, as duration varies depending on the target audience, specific objectives, and context of the intervention. An investigation involving adults with chronic conditions developed a nine-month educational intervention divided into nursing consultations, group activities, and telephone follow-up [50]. The duration of health interventions plays a crucial role, as long-term interventions tend to produce more consistent effects [61]. Despite the sustainable benefits, prolonged interventions often pose challenges, such as participant dropouts over time and greater susceptibility to interference from uncontrollable external factors, such as changes in the socioeconomic context or healthcare services [62]. Among the studies included in the meta-analysis, only that by Doi-Kanno et al. [19] (from Brazil) was conducted in less than an hour (i.e., 20 min). This was the only intervention to use leaflets and it also did not find satisfactory results (e.g., improvement in health literacy indicators). This may be explained by the fact that older people, especially those living in low- and middle-income countries, have low educational levels. [63]. Moreover, the possibility of visual impairment increases with the advance in age, [64] which may also affect the understanding of the information presented in leaflets.

Follow-up is another fundamental aspect for assessing the sustainability and effectiveness of health interventions over time [65]. Constant monitoring enables identifying the maintenance of the benefits achieved (e.g., increase or decrease in post-intervention health literacy) [66]. Among the articles selected for this review, eight performed follow-up assessments, [19–21, 36, 37, 39, 40, 45] but heterogeneity was found in the follow-up period. Just as a very long intervention can have an impact on the development and results of studies (e.g., participant dropout and/or the influence of the external environment that cannot be controlled), [62] performing follow-up assessments long after the intervention (e.g., three, nine, or 12 months) may also be seen as detrimental to the results of interventions. Short intervals can overestimate results by capturing only the immediate effects, whereas excessively long periods without reinforcement of the applied strategies can lead to the underestimation of the real benefits due to loss of adherence or forgetting the content. This factor is even more relevant when dealing with older adults, in whom cognitive impairment can occur over time. Other issues, such as the influence of the external environment itself, should also be taken into account. Thus, future studies should involve assessments at increasing post-intervention intervals (i.e., 15 days, 30 days, 60 days, 90 days, and so on). We believe that assessments at shorter intervals can enable more satisfactory results, as suggested in a protocol study [67] and performed in a recent clinical trial [68].

Some studies did not include follow-up assessments, [35, 38, 41, 43, 46–49] which may constitute a methodological limitation, as the absence of follow-up may compromise the identification of possible relapses or the need for additional interventions to maintain the results [25]. The study conducted by Intarakamhang and Macaskill [52] involving adults 41 to 59 years of age constitutes an example of the positive effects of a health literacy intervention also maintained at the follow-up assessment. The authors of another study stated that the results of their work indicated that individuals with lower health literacy were more likely to not complete scheduled follow-ups, highlighting the need for follow-up strategies adapted to populations with different levels of health literacy [69]

There is no standard model for health literacy training, especially for older people. Many of the interventions identified in the literature are heterogeneous [70], which was no different in the present review. However, many of the interventions have structures that assist in the learning process, such as group activities [71] and individual activities [13, 70, 72] Group interventions tend to be more effective in aspects such as motivation, engagement, and changes in behavior, whereas individual interventions are more effective for the understanding of specific content. Moreover, interventions that are culturally adapted and specifically designed for the specificities of older people (e.g., low education level, auditory and visual deficits) can achieve satisfactory results in health literacy training, [70] which may explain the findings of the studies included in the meta-analysis.

This systematic review contributes to consolidating the available evidence on health literacy interventions for older people, identifying methodological gaps and suggesting effective strategies that can be replicated or adapted in different contexts. By critically analyzing existing studies, this work offers important insights for designing future studies, encouraging more robust interventions that assess long-term outcomes and consider the sociocultural specificities of this population to promote healthier and more independent aging.

Limitations

This systematic review with meta-analysis has limitations that should be considered. The use of a search strategy with terms exclusively in English may have resulted in the exclusion of articles published in other languages due to the lack of titles or abstracts in English. Articles published in languages other than English were considered eligible and included when retrieved, as the databases selected for the literature search index titles and abstracts in English regardless of the publication language. Another limitation concerns publication bias identified in the meta-analysis through the funnel plot (i.e., Supplementary Fig. 3b), which may be explained by the lack of interventions with negative results. This review was conducted using widely used international databases [73] and a search was also conducted including articles published in all languages, such as studies published in German [49] and Portuguese, [46] to reduce language bias. Publication bias can be identified in meta-analyses [74]. However, we performed a meta-analysis excluding two studies [36, 40] with values close to 4; the magnitude was 0.79 (SMD = 0.79, p = 0.007; 95% CI: 0.21–1.36; I² = 93.4%; p < 0.001) and no publication bias was identified (i.e., Egger’s and Begg’s tests with p > 0.05), which demonstrates that, despite having extreme values, these results did not significantly influence the final results. Moreover, there were no reason for the exclusion of these studies after the theoretical and methodological assessment carried out individually. Heterogeneity remained above 90% with and without the two studies [36, 40]. One possible explanation for the high heterogeneity in the meta-analyses is the intervention models, with variations in the activities, time, and content covered in the health literacy interventions, as demonstrated in Tables 1 and 2. Despite these limitations, the present review lends support to the creation of health literacy interventions for older people, seeking not only to improve health literacy indicators, but also other health-related outcomes.

Implications for nursing and health policy

Although it was not possible to identify an what appears to be a common model for health literacy interventions targeting older people, some findings can guide the planning of activities: interventions that involve three to 12 meetings, each lasting up to 100 min, appear to be the most favorable; the use of a control group and follow-up in a shorter period of time, such as 15, 30, 60, or 90 days after the intervention, are recommended to confirm the effects of the interventions; group interventions are more effective and combining group activities with other strategies, such as telephone calls, diaries, and home follow-up visits may be beneficial; the diversity of approaches is an important point, with multicomponent interventions involving the exchange of knowledge and experiences among older people, the use of videos, demonstrations, workshops, games, simulations, group activities, etc. The content of the interventions varied but, in most cases, addressed communication and access to health information, which are considered key topics. Lastly, it is important to emphasize that the intervention must be tailored to the culture and characteristics of the participants.

It is essential that health professionals be adequately trained to plan and implement health literacy interventions directed toward older adults. Furthermore, public policies aimed at supporting and promoting such interventions should be developed and sustained by governments and institutional stakeholders. The evidence indicates that these actions constitute a key strategy for advancing health outcomes among the aging populations.

Conclusion

This systematic review and meta-analysis synthesized evidence from studies that implemented health literacy interventions among older adults. Overall, the meta-analytic findings suggest that these interventions are associated with improvements in health literacy in both pre–post analyses and comparisons with control groups. However, these findings should be interpreted with caution due to the substantial heterogeneity observed across studies and evidence of publication bias in the intervention-versus-control analysis. Beyond health literacy, several studies reported favorable effects on additional health-related outcomes, including quality of life, health behaviors, self-care, self-efficacy, and depressive symptoms; however, these outcomes were not consistently assessed across studies. The heterogeneity in intervention formats, durations, and outcome measures limited the identification of a standardized intervention model or optimal intervention duration. Overall, the available evidence suggests that health literacy interventions may be a promising strategy to support autonomy and well-being among older adults, although the magnitude and sustainability of these effects remain uncertain. Future studies employing standardized methodologies, appropriate control groups, and well-defined follow-up periods are needed to clarify the strength, durability, and generalizability of these effects.

Authors’ contributions

JKSP, MAM-B, and BML designed the systematic review. JKSP, MAM-B, FSO, and BML conducted the literature search, selected studies, and extracted data from the primary studies. All other authors assisted in resolving issues. MAM-B, Orlandi FS, and BML conducted the analysis. JKSP wrote the first draft of the manuscript. All authors contributed to and approved the final manuscript.

Funding

This study was financed in part by the Brazilian fostering agencies Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES [Coordination for the Advancement of Higher Education Personnel])—Finance Code 001), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq [The National Council for Scientific and Technological Development] – Process number 308019/2023–7) and Universidade Federal de Mato Grosso do Sul (UFMS [Federal University of Mato Grosso do Sul]).

Data availability

Data sharing is not applicable to this article, as no new data were created or analyzed in the study.

Declarations

Ethics and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.