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 Table of Contents  
Year : 2021  |  Volume : 18  |  Issue : 2  |  Page : 57-61

Factors associated with low adherence to medications in heart failure

1 Department of Medicine, University of Benin Teaching Hospital, Benin, Edo, Nigeria
2 Department of Medicine, Edo Specialist Hospital, Benin, Edo, Nigeria

Date of Submission13-May-2021
Date of Decision17-Nov-2021
Date of Acceptance19-Nov-2021
Date of Web Publication10-Dec-2022

Correspondence Address:
Dr. Ehi J Ogbemudia
Department of Medicine, University of Benin Teaching Hospital, Benin, Edo
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njc.njc_7_21

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Background: Medical therapy is fundamental in the management of heart failure (HF), and it is associated with favorable outcomes. These outcomes are attainable with good adherence to medications. However, the level of adherence to HF medications and the associated factors have not been well documented in Nigeria.
Aim: The aim of the study is to determine the level of adherence to HF medications and the associated factors in HF patients.
Materials and Methods: This was a cross-sectional study of HF patients in a tertiary health facility. A researcher-administered questionnaire was used to obtain demographic variables, assess adherence to HF medications with the Morisky medication adherence (MA) scale, and determine barriers to adherence. The proportions of respondents with a high and low adherence were derived, and the associated factors were investigated with Chi-square tests and multiple logistic regression.
Results: They were 168 respondents with a median age of 63 years, and 94 (56%) were females. The median MA score was 4.13. Forty eight (28.6%) and 120 (71.4%) had high and low MA, respectively. The associations of comorbidities, method of payment, and alternative medicines with the level of adherence gave p values of 0.000, 0.002, and 0.000, respectively. Barriers to adherence were financial 43 (35.8%), forgetfulness 38 (31.7), and others constituted 44 (36.7%).
Conclusions: Adherence to HF medications is suboptimal. It is associated with out-of-pocket payment, comorbidities, and usage of alternative medicines. Financial constraint and forgetfulness are the common self-reported barriers to adherence. Interventions to address these factors should be initiated.

Keywords: Heart failure, medical therapy, medication adherence

How to cite this article:
Ogbemudia EJ, Aghimien E, Aghimien O D, Obasohan AO. Factors associated with low adherence to medications in heart failure. Nig J Cardiol 2021;18:57-61

How to cite this URL:
Ogbemudia EJ, Aghimien E, Aghimien O D, Obasohan AO. Factors associated with low adherence to medications in heart failure. Nig J Cardiol [serial online] 2021 [cited 2023 May 29];18:57-61. Available from: https://www.nigjcardiol.org/text.asp?2021/18/2/57/363146

  Introduction Top

The management of heart failure (HF) involves the use of medical therapy, implantable devices, or cardiac surgery. However, medical therapy (medications) is fundamental, it is lifelong, and involves different classes of medications. HF medical therapy is associated with considerable outcomes, which can only be achieved with good adherence to medications.[1],[2] Medication adherence (MA) is defined as a patient's ability to conform to the recommendations of a healthcare provider on the dosage, frequency, and timing of prescribed medicines.[3] It is a major self-care behavior, and it is associated with reduced number of HF hospitalizations, better health-related quality of life, and reduced mortality.[4],[5]

Nonadherence to HF medications is a known modifiable precipitant of acute decompensated HF, which contributes significantly to increased health-care costs for both patients and health institutions.[6] MA is affected by several factors, which could be to the patient, disease process, treatment regimen, and relationship with health-care provider.[7] The degree of adherence to HF medications and the related factors are not established in Nigeria because this practice of medication intake has not been extensively evaluated. Indeed, to the best of our knowledge, this is the first study in Nigeria to investigate the degree of adherence to HF medications and their related factors. Umar[8] studied MA in Jos, but it was general in patients with cardiovascular diseases, not specifically HF as in this index study.

Yayehd et al.[9] and N'Cho-Mottoh et al.[10] investigated MA in HF patients and reported a low level of adherence, but these studies were conducted abroad, in Togo, and Cote d'Ivoire, respectively. Therefore, their findings may not be applicable to our population. The hypothesis from preliminary clinical observations is that adherence to HF medications is suboptimal. Information from this study should inform stakeholders on the need to modify or intensify strategies for educational counseling. It should also guide policymakers on new interventions to initiate to improve adherence in HF patients. These interventions will ultimately improve outcomes and reduce healthcare cost. Furthermore, this study provides a basis and directive for future research on this subject.

Thus, this study seeks to determine the level of adherence to HF medications and the related factors.

  Materials and Methods Top

This was a descriptive cross-sectional survey of HF patients in a tertiary health center. It was conducted in the cardiac out patients' clinics over 5 months (October 2020 to February 2021). The protocol was approved by the hospitals' research and ethics committee on the 30th of September 2020, and the protocol number is ADM/E22/A/VOLVII/14830858. The ethical principles of the Helsinki declaration were observed during the course of the study.

The minimum sample size was determined with the Fisher statistical formula . A prevalence of 12%[11] was used with a confidence interval of 95% (1.96) and degree of accuracy set at 0.05. This gave a minimum sample size of 162 but a final size of 178 after computation of a 10% attrition rate.

Inclusion criteria

Adult HF patients (≥18 years) on medications diagnosed more than 6 months before the onset of the study were included.

Exclusion criteria

Adult HF patients on medications diagnosed <6 months before the onset of the study were excluded. Subjects with psychiatric illness and cognitive impairment were also excluded.

Eligible patients were consecutively enrolled in the study after written informed consent was obtained. A researcher-administered questionnaire was used to obtain data from the participants. The first section of the questionnaire was on demographic and clinical variables such as gender, age, marital status, level of education, duration of HF, and ejection fraction. Other variables included an estimate of monthly income, number of HF hospitalizations in the preceding 12 months, the presence of morbidities, and a history of having been counseled on the importance of MA. The number of doses per day, usage of alternative medicines, and method of payment for medications were also documented.

The second section of the questionnaire assessed the practice of taking HF medications with the 8-item Morisky MA Scale.[12] This scale has been well validated and has a good reliability coefficient with a Cronbach's alpha of 0.83.[12] The questionnaire had a total of 8 questions. The first 7 items had a yes or no response and were scored 0 and 1, respectively, except for item 5 which was scored 1 or 0, for a yes or no response. The response to the last question was assessed on a 5-point Likert scale of 4–0. 4 = never, 3 = once in a while, 2 = sometimes, 1 = most times, and 0 = always. These points were standardized by dividing by 4, which corresponds to 1 = never, while the others were 0.75, 0.5, 0.25, or 0, respectively. The total score was an aggregate of all the points with a minimum of 0 and a maximum of 8. The third and last session of the questionnaire sought possible reasons for failure to take medications as prescribed.

Definition of terms

High adherence to medications

A total score of 6 or more on the morisky medication adherence (MMA) scale.[13]

Low adherence to medications

A total score of <6 on the MMA scale.[13]

Data were entered into the international business machines statistical product and services solutions (IBM SPSS) version 22.0 (SPSS Inc., Chicago, IL, USA) software for analysis.

Ordinal data and nonnormally distributed continuous data were described using median and interquartile ranges. Categorical data were described using frequencies or proportions.

For nonparametrical distributions, the Chi-square test was used to compare proportions. Multiple linear regression was used to assess the relationship between independent variables and the outcome variables. A P < 0.05 was considered statistically significant.

  Results Top

One hundred and sixty-eight (168) respondents participated in the study. Males and females constituted 74 (44%) and 94 (56%), respectively. The median age was 63.5 years with an interquartile range of (55.2–72) years. The young, middle-aged, and elderly age groups constituted 14 (8.3%), 80 (47.6%), and 34 (44.0%), respectively. Fourteen (8.3%) had no formal education, while 30 (17.9%), 76 (45.2%), and 48 (28.6%) had primary, secondary, and tertiary education, respectively. One hundred and thirty (77.4%) were married, while 8 (4.8%) and 30 (17.9%) were single and widowed, respectively. The median duration of HF and ejection fraction were 2 years and 45% (35.38%–56.55%), respectively. Almost all the respondents, 160 (95.2%) had been counseled on the importance of MA. The median MA score was 4.13.

  Discussion Top

The results in [Figure 1] and the low median adherence score reveal that adherence to medications is suboptimal in HF patients. This observation is surprising because patients usually receive counseling on MA and other self-care practices before each clinic consultation. Lack of understanding or poor motivation may be responsible for this behavior. Poor adherence to HF medications increases the risk of acute decompensation due to hemodynamic derangements. Yayehd et al. in Togo.[9] also reported low adherence to HF medications, this is most likely due to similarity in population studied. However, Ali et al.[14] in Sudan reported a much higher adherence. Sociocultural differences in the population may explain the variance in results.
Figure 1: Level of adherence to heart failure medications

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[Table 1] shows that the method of payment for medications is associated with the level of MA. Respondents who paid out of pocket for medications had a significantly lower adherence compared with respondents with health insurance P = 0.002. This is expected because the uninsured have to bear all the costs of medications and health services, while the insured pays only a minimal fraction of the actual bill. Pallangyo et al.[15] reported a similar finding.
Table 1: Association between independent variables and level of medication adherence

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Comorbidities were also significantly associated with the level of MA [Table 1]. Respondents with comorbidities had a significantly lower MA compared with respondents without comorbidities P < 0.0001. This is not surprising because comorbidities increase the number of medications, and the frequency of daily doses, which is burdensome. Amininasab et al.[16] documented a similar finding.

[Table 1] also shows that MA is significantly higher in respondents who take only the prescribed orthodox medicines than in respondents who also take alternative medicines, P < 0.0001. This is expected because patients who indulge in alternative therapies usually withhold prescribed medicines, while on alternative remedies. N'Cho-Mottoh et al.[10] in Cote d'Ivoire reported likewise.

MA was not significantly different in respondents without formal or primary education than in respondents with secondary or tertiary education. This is not unexpected because adherence to medications or any self-care behavior is primarily a matter of personal conviction and motivation, not necessarily dependent on the level of education attained. This finding, however, differs from that of Rehman et al.[17] who reported a worse MA in the less educated.

The regression analysis in [Table 2] shows that only comorbidities and usage of alternative medicines have strong enough associations to predict adherence. These 2 factors should therefore be actively sought in patients. Financial constraint was the most common (33.3%) patient-reported barrier to MA [Table 3]. This is not surprising because the majority (45.2%) of the respondents are low-income earners [Table 4]. Patients in this socioeconomic class are usually more prevalent in government-owned hospitals like the study center than in private hospitals because of better accessibility of health care. Forgetfulness, the second most common barrier (30%) to adherence can be explained by very busy daily schedules or poor motivation.
Table 2: Predictors of medication adherence in heart failure

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Table 3: Patient reported barriers to medication adherence in heart failure

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Table 4: Sociodemographic characteristics of all respondents

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A limitation of this study is that the MMA scale is not an objective tool because it is based on patients' self-report. However, this study has highlighted the problem of medication nonadherence in HF patients and the associated factors. Implications for further research include an assessment of other HF self-care practices such as dietary and fluid restrictions, weight monitoring, appointment keeping, and exercise. Determination of the impact of interventions on the level of MA, and on outcomes will also provide useful information.

  Conclusions Top

This study has shown that adherence to medications is low in HF patients, and it is associated with multiple factors, which include the presence of comorbidities, the use of alternative medicines, and out-of-pocket payment for medications.

The following recommendations should help improve adherence. Counseling sessions should be educational. That is patients should be informed about the benefits of good adherence and dangers of nonadherence, and usage of traditional medicines instead of plain advice. Individual patients with poor MA should be referred to public health nurses or pharmacists. HF patients should have health insurance which should cover all the medications. The pharmaceutical industry should explore the possibility of combining medications of commonly co-existing cardiovascular diseases to help reduce pill burden. Stronger family ties should be encouraged to help improve MA.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

CONSENSUS Trial Study Group. Effects of enalapril on mortality in severe congestive heart failure. Results of the cooperative north Scandinavian enalapril survival study (CONSENSUS). N Engl J Med 1987;316:1429-35.  Back to cited text no. 1
Chatterjee S, Biondi-Zoccai G, Abbate A, D'Ascenzo F, Castagno D, Van Tassell B, et al. Benefits of β blockers in patients with heart failure and reduced ejection fraction: Network meta-analysis. BMJ 2013;346:f55.  Back to cited text no. 2
Sabate E. WHO Adherence Meeting Report. Geneva: World Health Organization; 2001.  Back to cited text no. 3
Shah D, Simms K, Barksdale D, Wu J. Improving medication adherence of patients with chronic heart failure: Challenges and solutions. Res Rep Clin Cardiol 2015;6:87-95.  Back to cited text no. 4
Wu JR, Moser DK, Chung ML, Lennie TA. Objectively measured, but not self-reported, medication adherence independently predicts event-free survival in patients with heart failure. J Card Fail 2008;14:203-10.  Back to cited text no. 5
Riles EM, Jain AV, Fendrick AM. Medication adherence and heart failure. Curr Cardiol Rep 2014;16:458.  Back to cited text no. 6
Ekman I, Andersson G, Boman K, Charlesworth A, Cleland JG, Poole-Wilson P, et al. Adherence and perception of medication in patients with chronic heart failure during a five-year randomised trial. Patient Educ Couns 2006;61:348-53.  Back to cited text no. 7
Umar D. Assessment of adherence to medication among cardiovascular disease outpatients in Jos university teaching hospital, Jos, Nigeria. World J Pharm Res. [doi: 10.20959/wjpr20177-8831].  Back to cited text no. 8
Yayehd K, Damorou F, N'cho Mottoh MP, Tchérou T, Johnson A, Pessinaba S, et al. Compliance to treatment in heart failure patients in Lomé. Ann Cardiol Angeiol (Paris) 2013;62:22-7.  Back to cited text no. 9
N'Cho-Mottoh MP, Boka B, Yayehd K, Iklo C, Traoré F, Bamba-Kamagate D, et al. Assessment of treatment adherence among black Africans with heart failure. Med Sante Trop 2015;25:373-6.  Back to cited text no. 10
Adeoti AO, Ajayi EA, Ajayi AO, Dada SA, Fadare JO, Akolawole M, et al. Pattern and outcome of medical admissions in Ekiti State university teaching hospital, Ado-Ekiti – A 5-year review. Am J Med Med Sci 2015;5:92-8.  Back to cited text no. 11
Morisky DE, Ang A, Krousel-Wood M, Ward HJ. Predictive validity of a medication adherence measure in an outpatient setting. J Clin Hypertens (Greenwich) 2008;10:348-54.  Back to cited text no. 12
Awad A, Osman N, Altayib S. Medication adherence among cardiac patients in Khartoum State, Sudan: A cross-sectional study. Cardiovasc J Afr 2017;28:350-5.  Back to cited text no. 13
Ali M, AL-Khadher A, Fadl-Elmula I, Amen W, Ahmed M. Compliance to treatment and quality of life of Sudanese patients with heart failure. Int J Prev Med Res 2015;1:40-4.  Back to cited text no. 14
Pallangyo P, Millinga J, Bhalia S, Mkojera Z, Misidai N, Swai HJ, et al. Medication adherence and survival among hospitalized heart failure patients in a tertiary hospital in Tanzania: A prospective cohort study. BMC Res Notes 2020;13:89.  Back to cited text no. 15
Amininasab SS, Lolaty HA, Moosazadeh M, Shafipour V. Medication adherence and its predictors among patients with heart failure. Nurs Midwifery Stud 2018;7:81-6.  Back to cited text no. 16
  [Full text]  
Rehman ZU, Siddiqui AK, Karim M, Majeed H, Hashim M. Medication non-adherence among patients with heart failure. Cureus 2019;11:e5346.  Back to cited text no. 17


  [Figure 1]

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


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