Factors Influencing Medication Non-Adherence in Patients with Chronic Diseases and Disabilities: Insights from a National Survey in Indonesia

Introduction

According to a nationwide research conducted by the Indonesian Ministry of Health, the older adults with disabilities and chronic diseases account for approximately 2.6% of the total population. ¹ The 2023 national Survey conducted in Indonesia reported that the prevalence of disability varied across specific types, including visual disabilities (0.6%), intellectual disabilities (1%), mental disabilities (0.8%), sensory disabilities (0.2%), and communication disabilities (0.5%).² Additionally, it is estimated that between 2.5% to 5% of Indonesians living with disabilities are at risk for suffering from chronic diseases.³ Individuals with disability are particularly vulnerable to a range of illnesses, largely due to poorer medication adherence (54.5%) within this population compared to those without disabilities (57.5%).⁴ Disability can hinder medication adherence due to various factors, including physical limitations, cognitive challenges to comprehend prescribed treatment, insufficient access to healthcare resources, and inadequate caregiver support in managing medication routines.^5–10 These factors have been widely identified in studies as key contributors to non-adherence among patients with disabilities.⁵

Non-adherence to medication is commonly observed among patients with chronic diseases as they are required to follow a long-term treatment plan.¹¹ Prior research has identified potential factors linked to non-adherence among patients with chronic diseases, including socioeconomic factors,¹² therapy-related factors,¹³ medical professionals and health system-related factors,¹² and patient-related factors, such as gender,¹⁴ treatments beliefs,¹⁵ and the presence of a disability.^5–7 However, there is still a lack of research on the factors contributing to medication non-adherence in patients with chronic diseases and disabilities. These patients may face different challenges that affect adherence compared to those without disabilities.

Moreover, studies examining the link between disability and medication non-adherence remain limited. In some cases, populations with disabilities have been excluded from medication adherence studies, leaving them unobserved.¹⁶ Relevant studies in Indonesia are still limited concerning the factors associated with medication non-adherence among patients with chronic diseases¹⁷ and treatment approaches specifically for chronic disease patients with disabilities,¹⁸ leaving the relationship between being physically or mentally impaired and medication non-adherence largely unexplored. A previous study in Indonesia found that individuals with disabilities and low physical activity were at greater risk of chronic diseases compared to disabled adults with moderate or high activity levels.¹⁸ Given the rising prevalence of chronic diseases in Indonesia¹⁹ and the increasing focus on inclusive healthcare, investigating how disability impacts medication adherence is particularly critical.²⁰ Such understanding is essential for optimizing treatment effectiveness for patients with disability and chronic disease through appropriate strategy.²¹ Therefore, this study aimed to assess the prevalence of medication non-adherence among patients with chronic diseases and disabilities in Indonesia and to identify the factors associated with medication non-adherence among these patients.

Material and Methods

This study is presented in accordance with the guideline for cross-sectional studies: Strengthening the Reporting of Observational Studies in Epidemiology (STROBE)²² [See Table S1].

Study Design and Data Source

Data were analyzed using the cross-sectional study design from a national longitudinal survey from the fifth wave of the Indonesian Family Life Survey (IFLS-5), which was collected from 2014 to 2015. The IFLS is a comprehensive health and socioeconomic survey conducted at both individual and community levels by the RAND Corporation.²³ The IFLS 5 survey was conducted through face-to-face interviews and covers a substantial portion of the population, representing 83% of Indonesians across thirteen provinces (North Sumatra, West Sumatra, South Sumatra, Lampung, DKI Jakarta, West Java, Central Java, DI Yogyakarta, East Java, Bali, West Nusa Tenggara, South Kalimantan, and South Sulawesi). Moreover, the survey has been conducted since 1993 and achieved a response rate of over 90%.²³ The IFLS study received approval from the ethical review boards of the RAND’s Human Subjects Protection Committee (No. s0064-06-01-CR01), and informed consent was obtained from respondents prior to the study. According to the 2022 Standard Operating Procedures of the Research Ethics Committee at Universitas Padjadjaran, Indonesia (No. POB/08/KEP), research involving existing data, publicly available documents, or pathological and diagnostic specimens that protect participants’ identities is exempt from ethical review requirements.

Study Population

Data were analyzed from a national IFLS 5 database selecting individuals who were at least 15 years old at the time of the interview and had been diagnosed with a chronic disease. Chronic disease was measured using a self-report questionnaire with the question, “Has a doctor, paramedic, nurse, or midwife ever told you that you had any of the following chronic diseases?”. The available options included diabetes, hypertension, asthma, long-term respiratory illnesses, cardiovascular diseases (heart attack, coronary heart disease, angina, or other heart health issues), liver disorders, stroke, cancer or malignancies, arthritis, uric acid, gout, high cholesterol levels, prostate disease, kidney disorders, stomach or other digestive disorders, mental health issues, and diseases related to memory. Respondents who answered “yes” to any of the chronic diseases were classified as having a chronic disease. Respondents without available data on disability and medication adherence were excluded.

Disability Measures

Disability is defined as any impaired condition of the body or mind that limits a person’s ability to perform certain activities and interact with their environment. Disability was assessed through a self-report interview with the question, “Has a doctor, paramedic, nurse, or midwife ever told you that you had any of the following disabilities?”. The response options included physical disabilities, brain or cognitive damage, vision problems, hearing problems, speech impediments, mental retardation, and autism. Respondents who answered “yes” to at least one of the options were classified into the disability group.

Outcome Measures

Medication non-adherence was assessed with the question, “Are you taking [types of medication] to treat [types of chronic disease] and its complications?”. Respondents who reported no medication for any of the chronic diseases were classified as non-adherent.

Potential Factors Associated with Medication Non-Adherence

Potential factors in this study were included based on previous studies.^5,24,25 Sociodemographic information was obtained through a self-reported questionnaire, which included gender (female or male), age (15–65 or over 65), formal educational background (unschooled/elementary/junior high/senior high/higher education), ethnicity (Javanese or non-Javanese), geographical residence (Java or non-Java), demographic residence (rural or urban), household size (1 person/2–6 people/more than 6 people).

Socioeconomic factors were assessed based on annual income categories (not working or having no income/less than 12 million rupiah/12–40 million rupiah/40–100 million rupiah/over 100 million rupiah, with approximately USD conversions of around 770 USD/770–2600 USD/2600 – 6405 USD/over 6405 USD).

Health-related factors were measured by variables such as health insurance ownership (yes or no), self-perceived health status (very healthy/somewhat healthy/somewhat unhealthy/very unhealthy), days of primary activities (eg, work, education, caregiving) missed due to poor health during the last month (1–7 days or more than 7 days),²⁶ body mass index (underweight [< 18.5 kg/m²], normal [18.5–22.9 kg/m²], overweight [23–24.9 kg/m²], and obesity [≥ 25 kg/m²]),²⁷ smoking behavior (non-smoker/former smoker/active smoker), the need for assistance with daily tasks based on basic Activities of Daily Living (ADLs), such as bathing, dressing, and eating, as well as Instrumental Activities of Daily Living (IADLs), including using transportation and preparing meals (yes or no),^28,29 and the use of aids such as glasses or corrective lenses, hearing aids, or walking aids (yes or no).

Data Analysis

Descriptive statistics were used to summarize the respondents’ sociodemographic, economic, and health-related characteristics, as well as the types of chronic diseases, disabilities, and aids utilized. Binary logistic regression analyses were conducted to evaluate potential factors associated with medication non-adherence among patients with chronic diseases and disabilities. Factors that showed a significant association with the outcome at a significance level of p < 0.25 were included in the multivariate analysis.³⁰ Multivariate logistic regression was performed to calculate the odds ratios (ORs) and 95% confidence intervals (95% CIs), with significant levels set at p < 0.05. The Hosmer-Lemeshow and R-Squared tests were used to assess the model’s fit. All statistical analyses were carried out using the Statistical Package for the Social Sciences (SPSS) software version 27.0.

Results

Respondent’s Characteristics

A total of 74,251 respondents participated in the IFLS 5 survey (Figure 1). Respondents under 15 years of age and those with no available information on chronic diseases were excluded, resulting in a total of 11,419 respondents. After further excluding those with missing data, we included 1908 respondents with disabilities in the study. Among these 1908 participants, 1265 (66.3%) were non-adherent to medication (Table 1).

Table 1 Characteristics of Respondents with Chronic Diseases and Disabilities (N = 1908)

Figure 1 Selection process of study respondents.

Table 1 shows that the majority of respondents with chronic diseases and disabilities were female (62.7%), aged between 46 to 65 years (35.4%), graduated from senior high school (29.7%), non-Javanese (55.7%), resident of Java Island (57.3%), living in urban areas (72.3%), belonging to households of 2 to 6 people (58.6%), unemployed or without income (41%), having health insurance (60.8%), perceiving their health as somewhat healthy (48.9%), missing 1 to 7 days of activity due to poor health in the last month (45.8%). In addition, 45.9% had a normal body weight, 69.4% were non-smokers, 73.1% did not need assistance with daily tasks, and 62.1% used aids for daily activities.

Hypertension was the most prevalent chronic disease among respondents with disability (40.5%) (Table 2), followed by stomach or digestive diseases (42%), arthritis or rheumatism (20.1%), and high cholesterol (18.3%). Among 1908 respondents, the most common disabilities were visual impairment (82.1%), hearing problems (13.5%), and physical disabilities (7.2%). Other disabilities included brain impairment (4%), speech impediment (3.5%), mental retardation (1.2%), and autism (0.1%) (Table 3). Furthermore, most of the respondents wore glasses or corrective lenses to aid their vision (60%), while 0.6% used hearing aids (Table 2). Additionally, some reported using walking aids, including a walking cane (3.1%), walker (0.6%), manual wheelchair (1.6%), or electric wheelchair (0.1%) (Table 3).

Table 2 Prevalence of Chronic Diseases Among Respondents with Disability (N = 1908)

Table 3 Prevalence of Types of Disabilities and Aids Used Among Respondents (N = 1908)

Factors Associated with Medication Non-Adherence Among Respondents with Chronic Diseases and Disabilities

According to the bivariate analysis of potential factors (Table 4), variables including age, gender, education, residence, household size, annual income, health insurance ownership, self-perceived health status, active days missed, and use of aids were selected as potential factors associated with medication non-adherence. In the multivariate analysis, the following factors showed significant associations with medication non-adherence: being aged 15–30 years (OR = 1.65; 95% CI = 1.19–2.30) and aged 31–45 years (OR = 1.36; 95% CI = 1.01–1.84), self-perception of health as somewhat healthy (OR = 1.36; 95% CI = 1.09–1.69) or very unhealthy (OR = 1.73; 95% CI = 1.08–2.77), having no missed days of daily activities (OR = 1.51; 95% CI = 1.09–2.10), and did not use any visual/hearing/walking aids (OR = 1.24; 95% CI = 1.01–1.52) (Table 4).

Table 4 Regression Logistic Analysis Between Characteristics and Medication Adherence Among Respondents with Disability

The results of the Hosmer-Lemeshow test showed a p-value of 0.3481, indicating that the multivariable analysis was viable and met the model’s objectives. In addition, the pseudo-R-Squared test yielded a value of 0.0181, indicating that 1.81% of the variability in medication non-adherence was explained by the model.

Discussion

More than half of the patients with chronic diseases and disabilities in this study were non-adherent to their medication. We observed that key factors associated with medication non-adherence included being aged 15 to 45 years, having a self-perception of health as somewhat healthy or very unhealthy, not missing any active days due to poor health, and non-use of any aids.

We observed that the majority of respondents were non-adherent to medication. This finding aligns with previous research conducted among the older adults with physical and visual disabilities in Taiwan.³¹ One possible explanation may be due to the inverse correlation between medication adherence and disability. Patients with chronic diseases may face a higher prevalence of disability due to medication non-adherence. Our study contributes to the existing body of knowledge by highlighting how non-adherence can exacerbate chronic conditions and potentially lead to disability.³² Previous studies have shown that non-adherence to treatment for conditions like multiple sclerosis can worsen patients’ ability to perform daily activities.³³ Similarly, a recent study observed a decline in medication adherence among patients with diabetes following the onset of disability.⁸ Another possible explanation for our findings is that patients with disabilities face greater challenges, as their conditions often require more complex treatments which may hinder their ability to adhere to medication.^5,24

In our study, respondents aged 15 to 45 years showed a significant tendency for medication non-adherence compared to the older groups. This finding is consistent with previous studies that reported older age is positively associated with better medication adherence among both disabled and non-disabled patients with multiple sclerosis.³⁴ Although there is a lack of consensus on why age influences medication adherence, factors such as more frequent healthcare visits, higher insurance coverage, and increased family support in older adults may explain this correlation. This underlines the need for individuals with disabilities to receive adequate family support and access to healthcare services. Previous study has shown that these populations often face significant barriers to healthcare access and experience lower levels of social support.³⁵ Conversely, other studies suggest that older adults may experience lower adherence due to physical and cognitive decline,³⁶ leading to disabilities.⁵

Respondents who perceived themselves as “very unhealthy” were more likely to be non-adherent to medication compared to those who viewed their health as “somewhat unhealthy”. This finding is supported by previous study demonstrated that functional limitations commonly experienced by individuals with disability are correlated with poor self-perceived health.³⁷ Individuals with disabilities often perceive their health more negatively compared to those without disabilities.³⁸ Moreover, patients’ perceptions and attitudes toward their health have been identified as significant challenges to medication adherence.³⁹ Poor health perception may indicate belief in one’s limited ability to manage their chronic disease, consequently limiting adherence.⁴⁰ Interestingly, respondents who considered themselves “somewhat healthy” also exhibited a likelihood of non-adherence. This could be attributed to the possibility that a positive self-image of health may stem from a lack of awareness and perception regarding the seriousness of their chronic diseases. Moreover, prior study has shown that patients with chronic diseases and disabilities who maintain a positive and comprehensive perception of their health tend to be more adherent to their medication.⁴¹ This underscores the important role of healthcare professionals in enhancing patients’ understanding of their illness, which can empower them to better manage their conditions and adhere to their treatment plans, particularly among those with disabilities. Another study revealed that lower cognitive function and less functional limitations may lead individuals to have a more positive evaluation of their health status.⁴² This pattern may explain why our respondents perceived their health positively, especially as many noted they did not require assistance with daily activities and nearly 40% reported no difficulties in performing daily tasks. Therefore, assessing patients’ understanding of their condition could provide valuable insights into this correlation.

In line with our previous finding, we further observed that respondents who did not miss any active days due to poor health were more likely to be non-adherent to medication compared to those who missed more than seven active days. Although prior research has identified a significant correlation between restricted performance in daily activities and medication non-adherence,⁴³ this finding could be attributed to a higher tendency for those feeling burdened by their condition or illnesses to adhere more closely to their medication regimen.⁵ A reduced restriction in performing daily activities can foster a sense of well-being, even in the presence of chronic illness and disability, which may lead individuals to perceive their medication as unnecessary.⁴⁴ However, chronic illnesses typically require long-term therapy and medication adherence, regardless of perceived health status. This misperception can ultimately result in poor medication adherence.

We also observed a higher likelihood of medication non-adherence among respondents who did not use aids to support their daily activities. The use of aids may reflect an individual’s worsening symptoms, which could prompt them to continue their medication to alleviate the burden of their conditions.⁴² Additionally, the use of aids may indicate greater family support, which could help respondents adhere better to their medication. It is important to note that respondents may refrain from using assistive aids due to financial barrier, leading most of them to rely on either self-made or purchased aids; as the government supplies only a limited number of aids.⁴⁵ This lack of access to assistive devices can negatively impact their ability to perform daily activities, which may hinder their adherence to medication.

Our study highlights the need for a customized approach and policy to improve medication adherence for patients with chronic diseases and disabilities.^46,47

Given that individuals with disability in Indonesia often face discrimination,⁴⁸ there is an urgent need for action from the community, healthcare providers, and the government to ensure that individuals with disability have equal access to medical care, thereby optimizing their medication adherence. Providing specialized care for patients with chronic diseases and disabilities through medication therapy management could also be an effective strategy for improving chronic illness management. However, it is important to ensure that pharmacists’ knowledge, attitudes, and practices are adequately assessed prior to implementation.^49,50

Furthermore, the economic implications of medication non-adherence in this population should not be overlooked. Medication non-adherence in chronic diseases can lead to increased risk of mortality and elevated healthcare cost.^51,52 Future research should explore the potential cost savings associated with improving medication adherence among patients with disabilities and chronic diseases, which could be useful for developing targeted interventions.

To the best of our knowledge, this study is the first to utilize a nationwide population-based survey in Indonesia to examine factors associated with non-adherence to medication among patients with chronic diseases and disabilities. However, this study has several limitations. Data on chronic diseases, disabilities, and medication adherence were obtained through self-report which may have introduced recall bias and misclassification. Furthermore, the cross-sectional design complicates establishing absolute causality or directional associations. The low pseudo-R-squared value suggests that several unmeasured factors, such as family and social support,²⁵ the number of medications used,¹⁶ and healthcare provider-patient communication,^8,53 were not captured in the database. In addition, we could not include the specific types of disabilities as a potential factor, as patients may experience multiple disabilities simultaneously. Furthermore, the data used in this study may be considered outdated, as it captured only a specific time period. This limitation could result in some inconsistencies with current situations, underscoring the need for further research utilizing more recent data. However, the findings from this study can serve as a valuable baseline for future investigations. Furthermore, future longitudinal research should investigate the contributing factors to medication non-adherence in populations with chronic diseases and disabilities, taking sampling weights into account and including a more diverse demographic background. Additionally, targeted and tailored interventions are needed to enhance medication adherence for patients with chronic diseases and disabilities.

Conclusion

More than half of the patients with chronic diseases and disabilities were non-adherent to their medication. Factors associated with medication non-adherence included being aged 15 to 45 years, self-perceived health status as somewhat healthy or very unhealthy, not missing any active days due to poor health, and non-use of any aids. Therefore, interventions designed to improve medication adherence in this population should consider specific patient-related factors. Further research should explore practical strategies to improve medication adherence among patients with chronic diseases and disabilities, such as developing specific clinical guidelines to integrate adherence programs into routine care for these patients, digital medication reminder systems, community-based support, and caregiver involvement strategies.