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 Table of Contents  
Year : 2021  |  Volume : 18  |  Issue : 3  |  Page : 155-160

Medication nonadherence in Nigerian heart failure patients: A cross sectional study

1 Department of Medicine, Therapeutics and Toxicology, College of Medicine, University of Lagos, Nigeria
2 Department of Pharmacology, Therapeutics and Toxicology, College of Medicine, University of Lagos, Nigeria

Date of Submission04-Jan-2021
Date of Acceptance09-Jul-2021
Date of Web Publication23-Aug-2021

Correspondence Address:
Dr. Abdulwasiu Adeniyi Busari
Department of Pharmacology, Therapeutics and Toxicology, College of Medicine, University of Lagos, PMB12003 Idi-Araba, Lagos
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcls.jcls_1_21

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Background: Anti-failure therapy is vital to the reduction of morbidity and mortality associated with heart failure (HF). Medication nonadherence (MNA) has been identified as a major limiting factor for the attainment of therapeutic goals. This study aimed to determine the prevalence and characteristics of MNA in HF patients attending Lagos University Teaching Hospital (LUTH), Lagos. Methods: This was a descriptive cross-sectional study involving 202 previously diagnosed HF patients attending an outpatient clinic in LUTH. Data were obtained from patient's medical records and the use of an interviewer-administered questionnaire. Medication Adherence Report Scale 5-items was used to determine MNA. Results: Of the 202 HF subjects, 68% (n = 128) were aged 31–60 years, 65% (n = 132) were females, 58%, (n = 116) were taking ≤4 pills/day, 54.5% were taking pills twice daily, and 72.3% (n = 146) had comorbid conditions. The overall prevalence of MNA was 69.3% with ACE inhibitors having the highest MNA of 73.2% and angiotensin receptor blocker/neprilysin inhibitor having the least MNA of 0%. MNA was independent of age, gender, educational status, pill burden, duration of HF, history of HF admission, functional status, and specific comorbidities (P < 0.05). However, the presence of three comorbidities was associated with lower MNA (P < 0.05). Conclusion: There is a high prevalence of MNA in Nigerian HF patients. Measures aimed at improving adherence are imperative to improve outcomes in these patients.

Keywords: Heart failure, medication nonadherence, Nigerian

How to cite this article:
Ale OK, Busari AA, Irokosu ES, Akinyede AA, Usman SO, Olayem SO. Medication nonadherence in Nigerian heart failure patients: A cross sectional study. J Clin Sci 2021;18:155-60

How to cite this URL:
Ale OK, Busari AA, Irokosu ES, Akinyede AA, Usman SO, Olayem SO. Medication nonadherence in Nigerian heart failure patients: A cross sectional study. J Clin Sci [serial online] 2021 [cited 2023 May 28];18:155-60. Available from: https://www.jcsjournal.org/text.asp?2021/18/3/155/324400

  Introduction Top

Heart failure (HF) is a clinical syndrome characterized by typical symptoms (e.g., breathlessness, ankle swelling, and fatigue) that may be accompanied by signs caused by a structural and/or functional cardiac abnormality, resulting in reduced cardiac output and/or elevated intracardiac pressures at rest or during stress.[1]

In nearly all the regions of the world, HF is common with the prevalence on the rise.[1],[2] Over 20 million people worldwide have HF.[1],[2] The prevalence of HF in the general population is 1%–2%, rising to >10% in people >70 years of age.[1],[3],[4] In Nigeria, hospital-based prevalence studies show that HF is responsible for 9.4%–42.5% of medical admissions.[5],[6],[7],[8] HF is the most common complication of hypertension and cardiomyopathy in Africa.[9],[10] It accounts for 3%–7% of all medical admissions in Africa.[5],[6],[7],[8],[11] Adherence is defined by the World Health Organization (WHO) as the extent to which a person's behavior taking medication, following a diet, and/or executing lifestyle changes, corresponds with agreed recommendations from a health care provider.[12] Medication nonadherence (MNA) is the failure of a patient to conform to prescribed intervals and doses of a treatment regimen. A high prevalence of MNA has been documented in HF patients and is also a major hindrance to the achievement of optimum outcomes.[13],[14],[15] The effects of MNA include impaired quality of life, high health-care costs driven by high rates of hospital re-admissions and outpatient hospital care, and high mortality among HF patients.[13],[14],[15]

Factors such as age, sex, marital status, educational level, income, pill burden, cost of medications, family support, side effects of medications, and comorbidities are associated with MNA.[16],[17],[18],[19] There is a paucity of data on the prevalence and correlates of MNA in HF patients in Nigeria. This study aimed to determine the prevalence and characteristics of MNA in HF patients in a tertiary health institution in Lagos, Nigeria.

  Methods Top

Study design and location

This was a hospital-based cross-sectional study of subjects with a diagnosis of HF, placed on oral HF medications, and was being followed up at the cardiology outpatient clinic of the Lagos University Teaching Hospital (LUTH), Idi-Araba, Lagos. LUTH is a tertiary care hospital serving as a referral center for hospitals in Lagos, the commercial capital of Nigeria and its environs.

Study population

We studied 202 consecutive subjects aged ≥18 years, with a diagnosis of HF using the Framingham criteria who had been on oral HF medications for at least 6 months. Subjects must have had at least three outpatient clinic visits. Exclusion criteria were age <18 years, <3 outpatient clinic visits, critical illness, and refusal to give consent.

Data collection

Using a structured questionnaire after obtaining consent, data were collected from each subject. These included age, gender, marital status, ethnicity, education, occupation, income, number of medications taken per time, frequency of dosage, and total pill burden.

Clinical information such as duration of HF, presence, and types of comorbidities and the names and dosage of anti-failure medications prescribed was extracted from the patients' medical records. Height and weight were measured and body mass index was calculated. The New York Heart Association (NYHA) functional classification of all subjects was obtained.[20]

The primary outcome, i.e. MNA of subjects to anti-failure drugs, was assessed using the 5-item medication adherence report scale (MARS-5).[21] The MARS-5 consists of five statements of nonadherent behavior, i.e., forgetting, changing dosages, stopping, skipping, and using a particular medication scored on a 5-point Likert scale with 1 = always, 2 = often, 3 = sometimes, 4 = rarely, and 5 = never. For each drug, the least score obtainable, i.e., 5 represented the worst adherence, while a maximum score obtainable, i.e., 25 represented the best adherence. A score of 5–22 was considered nonadherent, while a score of 23–25 was considered adherent for a particular drug. The maximum score was 25. The overall adherence for each subject was a sum of the MARS-5 scores of all the anti-failure drugs divided by the number of anti-failure medications the subject was on. These included diuretics, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), beta-adrenergic blockers, aldosterone antagonists, ARB/neprilysin inhibitor (ARNI), and cardiac glycosides.

Data analysis

Data were analyzed using Statistical Package for Social Sciences (SPSS®) software for Windows, Version 20.0. Chicago, Illinois, United States. Categorical variables, i.e., gender, age group, marital status, educational status, adherence status, pill burden, number/types of comorbidities, and clinical characteristics, were presented as percentages and/or proportions. Differences in these variables were compared using the Chi-square test or Fisher's exact test as appropriate. P < 0.05 was taken as being statistically significant.

Ethical consideration

Ethical approval was granted by the Health Research Ethics Committee (HREC) of LUTH (reference no: ADM/DCST/HREC/2648). Participants were adequately informed in a language that they understood the nature, potential benefits, and risks of the study. Written informed consent was obtained from each subject. All data collected from the participants were kept confidential using a passworded retrieval system.

  Results Top

Most (68%, n = 128) of the subjects were in the 31–60 years age group and majority (65.5%, n = 132) were females [Figure 1] shows the magnitude of medication adherence/non-adherence among the heart failure subjects. Medication adherence among the subjects was independent of their sociodemographic characteristics. [Table 1] shows the sociodemographic characteristics of the HF subjects according to their medication adherence status. The monthly incomes of the subjects were as follows: 66.3% (n = 132) earned < N50,000, 15.6% (n = 31) earned N50,000 – N99,999, 11.6% (n = 23) earned N100,000–N199,999, and 6.5% (n = 13) earned over N200,000.
Figure 1: Distribution of medication adherence and non-adherence among the patients with chronic heart failure. The proportion of medication non-adherence (MNA) was 69.3% among the patients evaluated.

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Table 1: Sociodemographic characteristics of subjects according to their medication adherence status

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The majority (58%, n = 116) of the subjects were on ≤4 different medications. Twice-daily drug intake was the most frequent dosage (54.5%, n = 109). The medication adherence status of the subjects was independent of their pill burden. [Table 2] summarizes the pill burden of the HF subjects according to their medication adherence status.
Table 2: Pill burden of subjects according to their medication adherence

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MNA was highest (73.1%, n = 49) among subjects on ACEI and least (0%, n=0) among patients on ARNI. [Table 3] summarizes the individual medication adherence profiles of the anti-failure medications.
Table 3: Anti-failure medicationsf prescriptions and their adherence

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The etiology of HF in this cohort is as follows: Hypertensive heart disease (55%, n = 110), dilated cardiomyopathy (35.5%, n = 71), peripartal cardiomyopathy (2%, n = 4), ischemic heart disease (3.5%, n = 7), and rheumatic heart disease (1%, n = 2). Most (88.5%, n = 177) of the subjects' diagnosis of HF is ≤5 years old, while most (72%, n = 144) were in NYHA functional Class I. None of the subjects was in NYHA Class IV. [Table 4] shows the relationship between medication adherence and selected clinical characteristics of the subjects.
Table 4: Relationship between adherence and certain clinical characteristic of subjects

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The majority (72.3%, n = 146) of the HF subjects in this cohort had one or more comorbidities. The presence of three comorbidities in the HF subjects was associated with nonadherence in this study. [Table 5] five shows the relationship between the number of comorbidities in the HF subjects and medication adherence in this cohort. The most common comorbidity of HF in this cohort was hypertension, followed by dyslipidemia. [Table 6] shows the frequency of the various comorbidities and their relationships with medication adherence.
Table 5: Relationship between subjects' number of comorbidities and medication adherence

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Table 6: Relationship between specific comorbidities and medication adherence

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  Discussion Top

Adherence of patients to anti-failure medications is crucial to the attainment of optimal outcomes in HF.[22] Our study showed a high prevalence (70%) of MNA among patients with HF. A similar finding, i.e. high prevalence of MNA, has been documented for Nigerian patients with chronic illnesses such as hypertension and diabetes.[16],[17] Raimi et al. in a study of 50 hypertensive and 50 diabetic subjects documented 68% MNA in a Lagos clinic.[23] Abdulazeez et al. in a study of 220 subjects with diabetes mellitus in Ilorin reported an MNA of 73.6%.[16]

These values are higher than the 50% MNA documented by the WHO as the average MNA to long-term therapy in individuals with chronic illnesses.[24] It is also higher than 35.6% nonadherence to antihypertensive and antidiabetic medications by patients under managed health-care in the United States reported by Jing et al.[25] Hood et al. using the proportion of days covered to measure adherence in American HF patients documented MNA of 37%.[26]

Raimi et al. had previously documented the cost of medications/financial constraints as the major reason for MNA in Nigerians.[23] Abdulazeez et al. reported an association of medication adherence with higher patients' financial status.[16] A financially constrained patient may be reluctant to spend on medications, especially if there is no immediate attainment of treatment goals as seen in patients with multiple comorbidities.[27] Cost-related nonadherence is particularly more common in low-income earners.[9] Most of the subjects in this study are low-income earners with two-third of them earning less than N50,000/month. Out-of-pocket payment is the dominant mode of settling medical bills in Nigeria. This may result in inability to refill medications and a consequent low adherence. Conversely, the possession of good health insurance by the subjects in the American studies above may be a driver of high medication adherence. The poor patient reminder system in Nigeria may also contribute to the disparities observed in the MNA prevalence in these studies. Adherence was measured using the self-reporting method in our study and other Nigerian studies, while other indirect methods such as the proportion of days covered were used in the American study. These differences in the methods of MNA assessment may also underlie these differences in MNA.

MNA in our study was independent of the subjects' gender. This is at variance with the negative association between female gender and medication adherence documented by Raimi et al.[23] Differences in the type of tools used for the measurement of medication adherence in these studies may be responsible for this.

Elderly patients on treatment for chronic diseases have been reported to be more likely to be nonadherent to medications than younger patients.[28] However, data from our study showed MNA to be independent of the age of the subjects. The social support system in Nigeria which usually entrusts the responsibility for the administration of medications to the elderly to family members may have blunted in our study the expected higher MNA in the elderly.

Over 70% of the HF subjects in this study had one or more comorbidities. Multiple comorbidities may have a direct impact on the cost of patients' management such as the cost of medications, investigations, and hospital visits.[27] Conversely, low income may be a sequela of reduced productivity arising from HF and comorbidities[29],[30] However, the presence of comorbidities generally did not influence medication adherence in this study. The only exception was the presence of three comorbidities which were marginally (P = 0.049) associated with MNA.

Pill burden, the number of tablets/capsules that a patient takes regularly and the dosing frequencies of the pills, may influence medication adherence for MNA in patients with chronic illnesses, especially those with many comorbidities.[31] However, there was no significant association between pill burden and MNA in our study.

The class of drug with the least adherence in our study was ACEI. This may be attributed to the side effect profile of ACEI especially dry cough associated with its usage. ARB/neprilysin inhibitor (ARNI) had the best adherence. ARNI is expensive; hence, only highly motivated and financially comfortable patients are likely to be on it in low-middle income countries such as Nigeria. This may underlie the 100% adherence of patients on ARNI.

There is inconsistent evidence for the relationship between MNA and the number of comorbidities. Cholowski and Cantwell documented a positive relationship between the number of comorbidities and adherence in HF patients.[32] Granger et al. reported a negative relationship between adherence and the number of comorbidities, while Wu et al. documented a nonsignificant relationship between the number of comorbidities and medication adherence in HF patients.[33],[34] The presence of three comorbidities was associated with lower MNA in our study. All these inconsistencies may be due to differences in methods of assessing medication adherence.

Adherence was independent of specific comorbidities such as ischemic heart disease, hypertension, diabetes mellitus, dyslipidemia, chronic kidney disease, obesity, and stroke in our study. This is at variance with the documented higher medication adherence in HF patients with coronary heart disease, diabetes mellitus, and dyslipidemia.[35],[36] The above may be attributable to differences in study methodologies and sociocultural responses of the study populations to chronic illness.


This study was conducted in a single center and MNA was measured using a self-reporting method. Self-reporting tends to overestimate patients' actual adherence.[37] A single-center study may limit the generalization of the results of this study considering the diversity of the Nigerian population.

  Conclusion Top

There is a high prevalence of MNA in Nigerian HF patients and this may negatively impact the desired outcomes in these patients. Institution of measures to improve medication adherence will improve outcomes in Nigerian HF patients.


We thank Dr A. Chukwuemeka of the Cardiology Unit, Department of Medicine, LUTH, Idi-Araba, Lagos, Nigeria, for his contribution. The authors wish to thank Prof. I.A. Oreagba, Head of the Department of Pharmacology, Therapeutics, and Toxicology, of the College of Medicine, University of Lagos, for his unwavering support.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]

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