Design of a study protocol for a cross-sectional investigation into health literacy levels among elderly individuals in China

Abstract

Introduction

This nationwide, community-based, multicentre epidemiological survey seeks to evaluate the status, distribution and determinants of health literacy among Chinese adults aged 60 years and older. It addresses the limited representativeness of previous local studies and scarcity of data on advanced-age populations, thereby providing an evidence base for policies to improve health literacy in this demographic.

Methods and analysis

Led by the National Centre for Chronic and Non-communicable Disease Control and Prevention (NCNCD), this survey uses a multi-stage complex sampling design across 124 districts in all 31 provinces of China. Launched in 2022, the survey is conducted annually, recruiting 24 800 participants each year. Data collection includes demographic information, health literacy assessment (knowledge, attitudes and skills), health information channels, health behaviours and health status. Statistical analyses will assess health literacy levels, influencing factors and urban-rural/gender disparities.

Ethics and dissemination

Ethical approval was obtained from the NCNCD Ethical Review Committee (Approval No. 202110;12 July 2021). Ongoing reviews are conducted on an annual basis, and three ethical reviews have been completed. Findings will be disseminated through peer-reviewed publications and conference presentations, ensuring participant confidentiality.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• Employing a multi-stage complex sampling design covering all provinces nationwide ensures high representativeness of the sample.

• The substantial annual sample size (24,800 individuals per year) enhances the stability and statistical power of the results.

• Long-term dynamic data collection facilitates tracking trends in health literacy among the elderly.

• The cross-sectional design precludes direct inference of causal relationships between health literacy and influencing factors.

• Whilst complex sampling ensures representativeness, its implementation presents significant operational challenges and entails higher costs.

Introduction

Health literacy refers to an individual’s ability to access, understand and apply health information and services to maintain and promote health. ^{1 2} Low health literacy among older adults is associated with unhealthy behaviours, poor chronic disease management and increased healthcare costs. ^{3 4} In China, between 2012 and 2017, health literacy levels among individuals aged 60–69 remained persistently low (below 8% annually), highlighting an urgent need for improvement.⁵

Older adults with limited health literacy often demonstrate insufficient disease awareness, suboptimal health-related behaviours and poor self-management of chronic conditions. These deficiencies impede their effective interaction with the healthcare systems, negatively affecting the use of preventive care, clinical decision-making, physician-patient communication, treatment adherence and post-discharge rehabilitation outcomes.6,8

However, current surveys on health literacy among older adults in China remain incomplete, covering only those aged 60 to 69 and lacking data on the oldest-old. ⁹ Existing regional surveys also lack national representativeness. ^{10 11} There is an urgent need to conduct a nationwide survey on health literacy among older adults. This would involve representative community-based research to understand the current situation, influencing factors and preferences for accessing health information, thereby providing crucial evidence for subsequent policy development.

Methods and analysis

Health Literacy Questionnaire Development and Refinement

During the initial questionnaire design phase, we convened experts from multiple disciplines for several rounds of discussions. After reviewing domestic and international experiences and incorporating the characteristics of China’s elderly population, the initial draft of the questionnaire was finally designed.¹²

The pre-survey was conducted between June and August 2021 in the provinces of Shandong and Shanxi, with Shandong serving as the urban pilot site and Shanxi as the rural pilot site. A total of 205 valid responses were collected during the preliminary survey.The pre-survey identified medical terms that the elderly had difficulty understanding during the survey process, ambiguous expressions and sensitive issues; evaluated the time required to complete the survey and tested the adaptability of the questionnaire filling method. The results of the pre-surveys indicate that the Chinese Elderly Health Literacy Questionnaire exhibits high internal consistency (Cronbach’s α=0.92) and confirmatory factor analysis demonstrates good model fit (KMO＞0.90).Through small sample tests, potential problems in the questionnaire design were discovered and solved to ensure the validity and reliability of the formal survey.

Health Literacy Assessment Indicators

The questionnaire was modified from the national health literacy survey indicator system, with strategic adaptations to prioritise geriatric health priorities. Emphasis on occupational health, as well as child and maternal healthcare was reduced. Conversely, content on key geriatric health issues was incorporated, including Alzheimer’s disease, osteoporosis, bone health, falls, anxiety, depression, oral health, vision and hearing problems, sleep disorders, urinary incontinence and functional rehabilitation. The added content focuses on relevant knowledge, behaviours and self-management skills pertaining to these conditions.

The questionnaire items were developed primarily from the Basic Knowledge and Skills of Chinese Citizens’ Health Literacy (Trial) issued by the National Health Commission, ¹³ alongside nationally recognised guidelines including the Core Information on Elderly Health, ¹⁴ Core Information on the Prevention of Elderly Disability, ¹⁵ and Core Information on the Prevention and Intervention of Alzheimer’s Disease . ¹⁶ To further align with global geriatric care standards, the framework integrated recommendations from the WHO’s Integrated Care for Older People (ICOPE): A People-Centred Assessment and Pathway Guide for Primary Care,¹⁷ ensuring a focus on the multidimensional health needs of ageing populations.The specific indicator design is shown in table 1.

Table 1. Chinese elderly health literacy questionnaire index.

Primary indicators	Secondary indicators	Tertiary indicators	Content points
1 Basic Philosophy	1 Understanding of Health	1 Definition of Health	1 Health definition (mental, physical and social adaptation)
		2 Healthy Longevity	2 The focus of healthy longevity is maintaining the ability to live independently
	2 Attitude towards Health	3 Correct Understanding of Ageing and Disease	3 Ageing, disease and function
		4 Positive Understanding of Ageing	4 Correct Understanding of Successful Ageing
2 Basic Knowledge	3 Intrinsic Capacity	5 Mobility	5 Seek medical care promptly, exercise regularly and use assistive devices to maintain mobility
		6 Vitality and Nutrition Management	7 Maintain weight within a reasonable range and delay muscle loss 9 Oral healthcare to ensure adequate nutrition
		7 Vision	10 Regular screening, seek medical care promptly and effective means to improve and correct audio-visual impairment
		8 Hearing
		9 Psychological Capacity	13 Maintain a good mindset, learn to self-regulate, recognise early symptoms and seek medical care promptly
		10 Cognitive Capacity	14 Understand the signs of cognitive decline 15 Understand that diabetes and cerebrovascular disease can lead to cognitive decline 16 Understand the early symptoms of Alzheimer’s disease
	4 Healthy Lifestyle	11 Balanced Diet	8 Ensure proper nutrition and a balanced diet; add supplements when intake is insufficient
		12 Moderate Exercise	6 Encourage a variety of moderate exercises, encourage outdoor activities
		13 Quit Smoking and Limit Alcohol	11 Quit smoking early and limit alcohol intake
		14 Maintain Good Sleep	12 Keep regular hours and maintain good sleep
	5 Geriatric Syndromes	15 Urinary Incontinence	17 Understand the signs and risks of urinary incontinence; perform pelvic floor muscle exercises and treat enlarged prostate
		16 Falls	18 Prevent falls through exercise, vision correction and environmental modifications
3 Basic Skills	6 Information Acquisition Skills	17 Information Acquisition Ability	19 Pay attention to health information and obtain it through regular and authoritative channels
		18 Understanding and Communication Ability	20 Understand labels and instructions, recognise common danger signs and comprehend basic health knowledge
	7 Self-care Skills	19 Vaccination	21 Get influenza, pneumonia and shingles vaccines
		20 Health Products	22 Recognise and choose official purchase channels
		21 Social Participation	23 Engage in social activities
	8 Health Service Utilisation Ability	22 Regular Health Check-ups	24 Have at least one regular check-up annually; participate in cancer screening
		23 Utilisation of Basic Public Health Services	25 Use services (elderly health management and chronic disease management)
		24 Rational Medical Care Seeking	26 Choose medical institutions, bring medical history, and view treatment results rationally 27 Use medicines reasonably
	9 Chronic Disease Management Skills	25 Blood Pressure Control	28 Monitor blood pressure and take medicine regularly
		26 Blood Sugar Control	29 Monitor blood sugar, take medicine regularly and recognise hypoglycaemia
	10 Emergency Help-seeking Skills	27 Calling Emergency Services	30 Dial for emergencies and public health number
		28 Stroke Golden Time	31 Recognise early symptoms and seek medical help promptly
		29 Emergency Contacts and Medical Agents	32 Carry a health emergency card

Contents of the questionnaire

The questionnaire comprises 32 core questions designed to measure the health literacy of older adults in China based on the framework’s content points. These questions can be further categorised into three dimensions (table 1): (1) basic philosophy; (2) basic knowledge; and (3) basic skills, focusing on the understanding and attitude of the elderly towards health, their knowledge of healthy lifestyles and key areas of health, as well as their ability to obtain and utilise health information. Additionally, the questionnaire content also includes the basic demographic information of the respondents; channels, demands and preferences for obtaining health literacy-related information; personal health behaviour patterns and health status and supportive environment.^{18 19}

Study population

Eligibility criteria

Geographic Scope: 124 districts and counties across 31 provinces in mainland China.

Core Eligibility Criteria:

(1) Permanent community residents aged 60 years or older.

(2) Chinese citizens who have resided locally for ≥6 months within the past 12 months.

(3) Voluntary participation with signed informed consent.

(4) Possess normal communication abilities.

Exclusions:

(1)Residents of functional zones (eg, military barracks and sanatoriums).

(2) Individuals unable to complete core procedures.

Survey tools

The survey uses the Health Literacy Questionnaire for the Elderly in China developed by the National Centre for Chronic and Non-communicable Disease Control and Prevention (NCNCD), which was validated through several rounds of rigorous discussions and pre-surveys and has good reliability (Cronbach’s α=0.92) and validity (KMO＞0.90). The questionnaire has good reliability and validity, and it makes up for the shortcomings of the international common scale ‘HLS-EU’, which is not in line with the current situation of the grassroots level in China, as well as the shortcomings of the commonly used domestic scale ‘Chinese Citizen’s Health Literacy Questionnaire’, which fails to cover the key issues of the elderly. The self-developed Chinese Health Literacy Questionnaire for the Elderly is designed to address the need for localised measurement of health literacy among the elderly in China and follows a strict validation process, so it can be used in the study, and the results have good representativeness and credibility.

The questionnaire consists of 32 questions with a full score of 52 points. The standard for determining health literacy: if the questionnaire score reaches 80% or more of the total score, that is, the questionnaire score is greater than or equal to 42 points, the person is judged to have health literacy.

Sample Size Calculation

The sample size was calculated through a stratified approach, considering two primary dimensions: urban/rural residence and gender. At the gender dimension, participants were stratified into male and female subgroups. For the urban/rural dimension, rural areas encompassed county-level cities and lower administrative units, whereas urban areas included urban districts. ²⁰ By combining these two stratification factors, the overall population was divided into four layers.

The sample size was determined based on the following formula:

$${\displaystyle {\displaystyle \mathrm{N}=deff\frac{{\mu }_{\alpha }^2\times p\times \left(1-p\right)}{d^2}}}$$

Parameters:

${\mu }_{\alpha }$ = 1.96 (Z-score for $\mathrm{\alpha }$ = 0.05);

p=10% (baseline health literacy prevalence from pilot studies);

d=1.5% (absolute error margin);

deff=3 (design effect accounting for clustering).

According to these parameters, the average sample size required for each layer was approximately 4609 people. Considering gender, urban/rural stratification and an 80% response rate, the minimum sample size was determined to be 23 049 people. Therefore, 200 respondents were planned to be selected from each of the 124 survey counties (cities, districts), resulting in a total sample size of 24 800 people.

Sampling Design

This is a nationwide community-based multicentre epidemiological survey. The specific sampling procedures are as follows and can be found in table 2:

Table 2. Sample design of Health literacy survey of Chinese elderly.

Sampling phase	Sample allocation	Sampling method
First Stage	Selecting 2 districts and two counties (county-level cities)	Proportional to population size cluster sampling (PPS)
Second Stage	Selecting two townships (streets)	Proportional to population size cluster sampling (PPS)
Third Stage	Selecting two administrative villages (residents’ committees) or merged sampling units	Proportional to population size cluster sampling (PPS)
Fourth Stage	Selecting 50 permanent residents aged ≥60 years	Simple random sampling

Stage 1: County (City, District) Sampling

Led by the National Centre for Disease Control and Prevention (China CDC), the sampling framework used provinces (31 administrative units, including autonomous regions and municipalities) as primary strata. Using probability-proportional-to-size (PPS) sampling aligned with national administrative divisions, two urban districts and two rural counties (or county-level cities) were randomly selected per province. Urban/rural classification followed governmental criteria: districts as urban; counties and county-level cities as rural. ²¹ This yielded 124 monitoring sites (68 urban, 56 rural).

Stage 2: Township (Sub-district) Sampling

Provincial CDCs, in collaboration with county/district CDCs and under technical supervision from China CDC, implemented this phase. Selected monitoring sites compiled and submitted lists of all townships/sub-districts and their permanent elderly populations (aged ≥60 years). Following validation by higher-level CDCs, two townships/sub-districts were randomly selected per county using PPS, resulting in 248 townships/sub-districts nationwide.

Stage 3: Administrative Village (Residential Committee) Sampling

Provincial and county CDCs, guided by China CDC, oversaw this stage. Based on stage 2 outputs, townships/sub-districts provided rosters of administrative villages/residential committees and their elderly populations. PPS sampling selected two villages/committees per township. To ensure adequate sample size, adjacent units were merged if individual villages had <50 eligible residents. This generated 496 villages/committees from 248 townships.

Stage 4: Sampling of Elderly Residents

Local CDCs generated registries of all permanent residents aged ≥60 years within selected villages/committees. Simple random sampling recruited 50 participants per village, with age quotas (60–69, 70–79, ≥80 years) calibrated to reflect local demographic distributions.

Investigation process

Pre-Investigation Preparations

Comprehensive preparations must be completed prior to field surveys: First, secure support from local governments and primary healthcare institutions and conduct outreach to enhance resident participation. Second, establish a survey team with clearly defined responsibilities, equipped with standardised survey tools and emergency supplies provided by the national committee.

The survey employs a combined approach of door-to-door visits and centralised collection. Certified investigators will conduct interviews using the Computer-Assisted Personal Interviewing (CAPI) system. Home visits will be provided for individuals with mobility challenges. Where feasible, centralised collection points will be established at community health service centres to enhance efficiency and convenience.

Investigation Execution

The on-site investigation follows a standardised two-step process. First, during the participant appointment phase, interviewers use phone calls, face-to-face visits and text notifications to make appointments in line with the inclusion and exclusion criteria. All interviewers use a structured verification process and standardised communication protocols and document outreach results in real-time.

Second, the investigation implementation phase is conducted at dedicated sites. To ensure an orderly workflow, physically separate functional zones, namely, registration and investigation areas, are established. Investigators are in charge of participant identity verification, digital consent management and collecting core assessment data via CAPI. The assessment centre administers the Health Literacy Inventory (HLI) and handles data encryption.

Post-Investigation Procedures

Following data collection, all questionnaires undergo rigorous quality control procedures. Informed by pre-survey findings which indicated that the response time is a reliable indicator of data quality, the formal survey was administered via a dedicated online platform with an integrated timer. All questionnaires are initially reviewed and approved by staff at corresponding levels of the Centre for Disease Control and Prevention (CDC). This initial review verifies completeness, checks for logical inconsistencies and confirms that the questionnaire was filled out by the participant themselves. Once approved, the data are reported to the National Centre for Disease Control and Prevention (NCDC) at each level for archiving.

Specific quality control measures, based on response time, are implemented as follows:

(1）Questionnaires completed in less than 20 min must be redone. According to the preliminary survey, the average response time of the elderly aged 60 and above is 25–35 min. As the hearing and visual functions of the elderly decline with age and their comprehension ability decreases, this measure can avoid the impact of perfunctory responses on the survey results.

(2）Those completed in 20–25 min are checked by county, district and provincial quality control staff at a 100% rate. It is considered that although there may be elderly people with higher education and faster response time, who can complete the questionnaire within 20–25 min, due to the less frequent occurrence of this situation and the requirements for data quality, all quality control is carried out by the staff.

(3）Questionnaires completed in 25–30 min are checked at an 80% rate. The response time is in line with the pre-survey time interval, and the staff will conduct proportionate quality control for the data quality requirements.

(4）Those completed in over 30 min are checked at a 10% rate.The response time is in line with the pre-survey time interval and the staff will conduct proportionate quality control for the data quality requirements.

Quality Control Measures

Personnel Training

The state conducts national-level personnel training, and provinces determine their own secondary-level training methods, scale and venue. This survey uses a training approach combining lectures and practice. Each provincial disease control and prevention centre organises staff from relevant counties (cities, districts) to join national training. To ensure quality, each training link is subject to quality control.

Trainers are required to possess a thorough understanding of the survey content, demonstrate strong communication skills and training experience, and evaluate training effectiveness post-training. Trainees should have a public health or medical background, good language expression ability, be fluent in Mandarin and be familiar with local project-area dialects. Training discipline, attendance and assessment systems should be strictly enforced. Trainees should be assessed on the survey plan, questionnaire etc., and an electronic trainee information file should be created. Those scoring below 80 will be retrained or replaced.

Replacement Principle

The replacement ratio is strictly controlled within 10%. Replacements must be selected from non-sampled individuals within the same village or residential committee, following the principle of matching the original sample in terms of similar age and the same gender. Replacement operations are only allowed under specific circumstances, including but not limited to the following situations: (1) confirmed respondent has permanently vacated the designated survey area; (2) temporary unavailability: need to coordinate rescheduling through local community administrative bodies or direct respondent communication and require more than three documented contact attempts (multiple same-day attempts count as single instance). Initiate substitute selection procedures after verified contact failure; (3) if the respondent is unwilling to accept the investigation, trained investigators are needed to enhance engagement through standardised persuasion protocols. Replacing actively after more than three documented refusal; (4) if the respondent cannot participate in the investigation due to health reasons, a replacement is required. For respondents likely to recover within the investigation period, the next investigation time is scheduled.

Implementation of On-site Investigation

For group-administered questionnaires, staggered scheduling (eg, 30–40 min cohort intervals) is implemented to prevent overcrowding and maintain procedural integrity. To ensure methodological objectivity, investigators shall maintain a minimum 3-m operational buffer between workstations to prevent cross-participant interference, with priority given to separate investigation rooms. All survey instruments must be administered sequentially without any deviation from the established item sequence, prohibiting both question omission and leading phrasing. When engaging respondents with limited educational attainment, investigators may provide calibrated clarifications strictly adhering to the questionnaire’s original semantic parameters, avoiding interpretive bias. Each completed questionnaire undergoes mandatory on-site verification with immediate anomaly resolution prior to submission. Quality assurance supervisor shall oversee all investigative operations to enforce standardised compliance.

Data Entry, Sorting and Analysis Stage

There are two ways to collect data: centralised survey, that is, to gather the selected elderly people to participate in the survey in a designated area; household survey, that is, for the elderly who are not convenient to move, the survey personnel will visit their homes to complete the survey. In the process of survey, a unified information collection system is adopted to ensure the consistency of data.

Each investigation site shall designate dedicated personnel to systematically execute the collection, organisation, secure storage and backup of survey-related materials. All data must be reported and feedback provided in accordance with protocol requirements through the unified data collection and management platform developed by the NCNCD. Using professional data analysis software, comprehensive data cleaning and logical validation shall be performed to ensure accuracy and consistency, with problematic questionnaires systematically discarded. For regions exhibiting higher rates of invalid questionnaires, the NCNCD will organise targeted verification initiatives to enhance data quality. On completion of the data cleaning process, appropriate statistical analysis methods will be applied to conduct in-depth examination of the dataset.

Ethics and dissemination

The study was approved by the NCNCD Ethical Review Committee on 12 July 2021 (NO.202110). It is conducted in accordance with the Declaration of Helsinki and all applicable national and international laws, regulations and standards, including archiving of essential documents. Patients agreeing to participate in the study must sign an informed consent form approved according to local regulations. The study site staff member conducting the consent process must also sign the consent form on the same occasion.

Final data analysis and disclosure of contractual agreements will be done by the NCNCD, Elderly Health Department, which will limit the access of non-investigators to the final trial data set. The monitors, auditors, authorised personnel of the sponsor, health authority inspectors or their agents and authorised members of Independent Ethics Committees/Institutional Review Boards will be given direct access to the source data and documentation (eg, medical records, place of residence and personal income) on request, provided that patient confidentiality is maintained in accordance with local requirements.

The survey is expected to map the age gradient of health literacy among the elderly in China, quantify the differences in literacy and the factors affecting it among people aged 60–74 (low age), 75–89 (middle to high age) and ≥90 (longevity), to identify the targets of intervention for vulnerable groups and to reveal the mechanisms of the literacy deficits of the elderly living alone in rural areas and the low-educated and senior people. It is expected to provide target coordinates for accurate health promotion, construct health promotion toolkits and develop health promotion videos, lectures and brochures applicable to elderly people with different characteristics and cultures. A dynamic literacy monitoring platform will be set up to continuously track the effects of interventions and support scientific governance to cope with the wave of ageing in a phased manner. This survey can fill in the blank data on the health literacy of Chinese seniors over 69 years old and also provide decision-making parameters for the reconstruction of the ageing-appropriate health service system.

Findings of this study will be disseminated through peer review publications and conference presentations. No information which could lead to the identification of patients will be included in the dissemination of results.

Data availability statement

Data are available upon reasonable request. The raw data set generated and analysed during this study contains sensitive information and is not publicly available due to the privacy concerns. However, an anonymised data set, stripped of all direct identifiers, is available upon request from the corresponding author. Interested researchers should contact the corresponding author to request access and obtain the data use agreement.