|Year : 2019 | Volume
| Issue : 2 | Page : 129-137
Medication adherence and patient satisfaction among hypertensive patients attending outpatient clinic in Lagos University Teaching Hospital, Nigeria
Esther O Oluwole1, Olatokunbo Osibogun2, Oluseyi Adegoke3, Adebola A Adejimi1, Ajoke M Adewole1, Akin Osibogun1
1 Department of Community Health and Primary Care, College of Medicine, University of Lagos, Surulere, Lagos, Nigeria
2 Department of Epidemiology, Robert Stempel College of Public Health and Social Work, Miami, Florida, USA
3 Department of Internal Medicine, College of Medicine, University of Lagos, Surulere, Lagos, Nigeria
|Date of Web Publication||10-Jun-2019|
Dr. Esther O Oluwole
Department of Community Health and Primary Care, College of Medicine, University of Lagos, P.M.B. 12003, Surulere, Lagos
Source of Support: None, Conflict of Interest: None
Background of the Study: Low adherence is an essential element responsible for impaired effectiveness and efficiency in the pharmacological treatment of hypertension. Patient satisfaction is an important measure of healthcare quality and is a crucial determinant of patients' perspective on behavioural intention. Aims: This study determined the association between medication adherence and treatment satisfaction among hypertensive patients attending hypertension outpatient clinic in Lagos University Teaching Hospital (LUTH), Nigeria. Materials and Methods: Setting – The study setting was LUTH; a descriptive cross-sectional study was conducted. Study design – Hypertensive patients were consecutively recruited from the outpatient clinic. Medication adherence was assessed using the 8-item Morisky Medication Adherence Scale and treatment satisfaction was assessed using the 14-item Treatment Satisfaction Questionnaire for Medication. Statistical Analysis: Univariate and linear regression analyses were conducted using STATA software version 14.1 (StataCorp LP, College Station, TX, USA). Statistical significance was set at P ≤ 0.05. Results: A total of 500 respondents with a mean age of 58.9 ± 13.3 years participated in the study. Overall, majority (446 [89.2%]) of the respondents in this study had 'moderate' adherence to antihypertensive medication. However, only five (1.0%) respondents reported 'high' adherence. Mean scores were highest in the moderate adherence category for all satisfaction domains and overall domain. Treatment satisfaction was associated with medication adherence, and was statistically significant (P = 0.000). Conclusion: One in every hundred patients had high adherence to hypertensive medication in this study, and there was a positive association between treatment satisfaction and medication adherence. Continuous patient-specific and tailored adherence education and counselling for hypertensive patients is recommended.
Keywords: Hypertension, medication adherence, Nigeria, outpatient clinic, treatment satisfaction
|How to cite this article:|
Oluwole EO, Osibogun O, Adegoke O, Adejimi AA, Adewole AM, Osibogun A. Medication adherence and patient satisfaction among hypertensive patients attending outpatient clinic in Lagos University Teaching Hospital, Nigeria. Niger Postgrad Med J 2019;26:129-37
|How to cite this URL:|
Oluwole EO, Osibogun O, Adegoke O, Adejimi AA, Adewole AM, Osibogun A. Medication adherence and patient satisfaction among hypertensive patients attending outpatient clinic in Lagos University Teaching Hospital, Nigeria. Niger Postgrad Med J [serial online] 2019 [cited 2019 Jun 18];26:129-37. Available from: http://www.npmj.org/text.asp?2019/26/2/129/259917
| Introduction|| |
Hypertension, also known as high or raised blood pressure (BP), is a condition in which the systolic and diastolic BP is equal to or more than 140 mmHg and 90 mmHg, respectively. Hypertension is an important risk factor in the development of coronary artery disease, a major non-communicable disease, and a leading cause of cardiovascular disease-related deaths worldwide. It constitutes a public health challenge and contributes significantly to morbidity, financial burden to healthcare and mortality. Hypertension currently affects nearly 78 million adults in the United States and is a major modifiable risk factor for other cardiovascular diseases and stroke.,, Worldwide, about 1 billion adults aged 18 years and above are estimated to have hypertension and two-thirds of the population resides in developing countries, while about 1.56 million adults are estimated to be living with hypertension by 2025. A high prevalence of hypertension has been reported among the Nigerian population, with a crude prevalence of hypertension ranging from 6.2% to 48.9% for men and 10% to 47.3% for women. Prevalence across urban and rural population ranged from 9.5% to 51.6% and 4.8% to 43%, respectively, while the country's wide prevalence ranged from 12.4% to 34.8%. Another study among Nigerians reported a crude prevalence of hypertension from 2.1% to 47.2% in adults.
Medication adherence is one of the determinants of treatment success for hypertension, while poor medication adherence and lack of knowledge and awareness on hypertension have been stated as some of the primary reasons for poor hypertension control which directly impacts patients' quality of life., Patient satisfaction with medication is an important measure of healthcare quality as it offers information on the providers' success at meeting clients' expectations and is a key determinant of patients' perspective on behavioural intention. Different studies have demonstrated the role of treatment satisfaction with BP control.,, A study among adult Nigerians found medication adherence and BP control to be significantly associated with treatment satisfaction. The findings of the present study on medication adherence and treatment satisfaction of hypertensive patients attending outpatient clinic in Lagos University Teaching Hospital (LUTH) provide a valuable strategy for professional healthcare providers involved in the care of hypertensive patients. This study determined medication adherence and treatment satisfaction among hypertensive patients attending hypertension outpatient clinic in LUTH.
| Materials and Methods|| |
Ethical clearance for the study was requested, and approval was obtained from LUTH Health Research and Ethics Committee (REF No: ADM/DCST/HREC/APP/2384). A written informed consent was obtained from respondents before enrolment into the study. They were all informed about the purpose of the study and their right to refuse participation. Ethical conduct was maintained during data collection and throughout the research process. All questionnaires were made anonymous, and participation was voluntary.
The study setting was LUTH, a 700-bed facility occupying 92 acres of land, making it one of the largest teaching hospitals in Nigeria. It serves various categories of people and also serves as a referral hospital for Lagos and its adjoining states. The LUTH hypertension clinic runs every week and attends to an average of fifty follow-up patients per clinic day. Data were collected between 1 September and 30 November 2018. The LUTH Cardiology/hypertension clinic runs twice weekly and attends to an average of seventy patients per clinic day.
Study design, sample size determination and selection of participants
This was a descriptive, cross-sectional study. The minimum sample size was determined using Fisher's formula, with a standard normal deviation at 95% confidence interval (CI) (1.96), a prevalence rate of 0.429 (proportion of medication adherence among adult Nigerians with essential hypertension from a previous study) and the error of precision at ± 5% (0.05). The minimum sample size was 376; to adjust for non-response using an expected response rate of 80% (0.8), a sample size of 470 was calculated, but a total of 500 participants were recruited for this study. Random sampling by ballot was used to select eligible respondents. The clinic register was used as a sampling frame on each clinic day. At each clinic, 40–50 participants were selected by ballot from the list based on the number of patients per clinic/day. The procedure was repeated on each clinic day until the sample size was attained.
Study instrument and data collection
The survey questionnaire was developed and adapted for this study from a review of relevant literature. The questionnaire was divided into three sections as follows: Section A elicited sociodemographic data of the respondents, Section B consisted of questions on information on medication adherence, while Section C was on hypertension treatment satisfaction. Ten percent of the total questionnaires (50) was pre-tested at the Lagos State University Teaching Hospital before the commencement of the study and questions were modified accordingly.
Three research assistants who could speak English, Yoruba and Pidgin English were recruited and trained to help with the distribution and collection of the questionnaires under the supervision of an experienced consultant public health physician.
Each respondent had the questions and response options read out to him/her. For the respondents who could not understand English, the questions were translated by the research assistants into Yoruba and Pidgin English as required.
Dependent variable: Medication adherence
Medication adherence was assessed using the validated eight-item Morisky Medication Adherence Scale (MMAS8). MMAS-8 is an 8-item questionnaire with seven yes/no questions, while the last question is a 5-point Likert scale. We summarised the overall mean score for medication adherence and grouped medication adherence into the following three categories: a score of 0 was considered as high adherence, a score of 1–4 was considered as moderate adherence and a score of >4 as low adherence. The internal consistency and validity of the questionnaire was represented by a Cronbach's alpha value of 0.69.
Independent variable: Treatment satisfaction
Hypertension treatment satisfaction was assessed with the Treatment Satisfaction Questionnaire for Medication (TSQM). The 14 items of the TSQM cover the following four domains: effectiveness; side Effects; convenience and global satisfaction, which were based on a 7-point Likert scale ranging from 'extremely dissatisfied (1 point) to extremely satisfied (7 points).' Each domain was scored according to the responses provided, and an overall satisfaction score from the combination of these four domains was obtained, with higher scores reflecting higher satisfaction. We assessed the internal consistency and validity of the questionnaire as follows: effectiveness of 3 items: Cronbach's alpha 0.90; side effects with 4 items, Cronbach's alpha 0.97; convenience of 3 items, Cronbach's alpha 0.73 and global satisfaction scale of 3 items, Cronbach's alpha 0.78.
All statistical analyses were performed using STATA version 14.1 statistical package (StataCorp LP, College Station, TX, USA). We summarised the sociodemographic characteristics, medication adherence categories and patient satisfaction domain scores of the study participants for the overall population. We used the Chi-square test and ANOVA to determine the statistical significance of observed differences for categorical and continuous variables, respectively. Two linear regression models were used to estimate the beta coefficients and the corresponding 95% CIs for the associations between medication adherence and patient satisfaction. The first model was unadjusted, whereas the second was adjusted for age, sex, ethnic group, marital status, education, occupation, income and mode of payment for healthcare.
Adult hypertensive patients aged ≥18 years who were registered and gave informed consent and had been placed on antihypertensive medications for at least 6 months before the study were included in the study.
Patients with other disease apart from hypertension and pregnant women were excluded from the study.
| Results|| |
Basic sociodemographic characteristics of the study participants (n = 500) are shown in [Table 1]. Among these hypertensive patients, 284 (56.8%) were female, and the mean age ± standard deviation (SD) was 58.9 ± 13.3. Majority of the study participants were married (79.8%) and paid out of pocket for healthcare (71.4%).
|Table 1: Basic demographic characteristics of the study participants (n=500)|
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[Table 2] shows the summarisation of scores for treatment satisfaction and medication adherence among the respondents. Majority (89.2%) of the participants had moderate adherence. The mean adherence score ± SD for the study sample was 2.5 ± 1.6 out of an overall score of 8, whereas the mean scores ± SD for the satisfaction domains were as follows: effectiveness: 16.2 ± 2.4, side effects: 26.2 ± 7.5, convenience: 16.8 ± 1.8, global satisfaction: 16.4 ± 2.1 and overall satisfaction: 75.6 ± 10.5.
|Table 2: Medication adherence and treatment satisfaction among respondents (n=500)|
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[Table 3] shows the distribution of hypertensive patients by medication adherence. Mean scores for the patient satisfaction domains differed by medication adherence category. For effectiveness, the mean scores ± SD were 15.0 ± 2.9, 16.3 ± 2.3 and 15.8 ± 2.5 for low, moderate and high adherence, respectively (P = 0.0019). For side effects, the mean scores ± SD were 22.5 ± 9.8, 26.6 ± 7.1 and 23.8 ± 9.3 for low, moderate and high adherence, respectively (P = 0.0010). For convenience, the mean scores ± SD were 16.1 ± 2.9, 16.9 ± 1.7 and 16.6 ± 1.1 for low, moderate and high scores, respectively (P = 0.0343). For global satisfaction, the mean scores ± SD were 15.3 ± 2.8, 16.6 ± 2.0 and 16.0 ± 1.0 for low, moderate and high adherence, respectively (P = 0.0005). For overall satisfaction, the mean scores ± SD were 69.0 ± 14.8, 76.3 ± 9.6 and 72.2 ± 11.9 for low, moderate and high adherence, respectively (P < 0.0001). The mean scores were highest in the moderate adherence category for all satisfaction domains and overall domain. There was no significant association between payment forms and medication adherence (P > 0.05) [Table 3].
Males had lower mean scores ± SD (15.8 ± 2.6) for effectiveness compared to females (16.4 ± 2.2) (P < 0.05) [Table 4]. Igbos and other ethnic groups reported lower mean scores for the side effect domain (25.2 ± 8.1 and 25.0 ± 8.3, respectively), compared to Yorubas (27.0 ± 6.9) respectively (P < 0.05). Similarly, statistically significant differences between global satisfaction and ethnic group were observed (P < 0.05) [Table 4]. Furthermore, there were statistically significant differences between ethnic group and overall satisfaction (P = 0.0026), as well as marital status with overall satisfaction (P = 0.0153) [Table 5].
|Table 4: Mean treatment satisfaction scores across the study participants' characteristics|
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|Table 5: Mean overall treatment satisfaction scores across the study participants' characteristics|
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[Table 6] shows the regression analyses of the association between medication adherence and patient satisfaction. In the unadjusted model (model 1), all satisfaction domains, including the overall satisfaction, were inversely associated with medication adherence. For example, a 1-unit increment in the overall satisfaction scores corresponds to a 0.05 decrease in the medication adherence score, where lower medication adherence scores are favourable in this study. A similar pattern of significant associations was observed between medication adherence and the individual satisfaction domains when the model was adjusted for the sociodemographic factors and mode of payment for healthcare [Table 6]. Compared to the Yoruba ethnic group, both Igbo and other ethnic groups were significantly inversely associated with overall satisfaction [Table 7]. Compared to married participants, single participants were significantly inversely associated with overall satisfaction. In addition, compared to insurance form of payment for healthcare, out-of-pocket and other forms of payment for healthcare were significantly directly associated with overall satisfaction (all P < 0.05) [Table 7].
|Table 6: Linear regression of the association between patient satisfaction and medication adherence|
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|Table 7: Multivariable linear regression of factors influencing patients' overall satisfaction|
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| Discussion|| |
The clinical benefits of medication are reduced when there is low or poor adherence, and this leads to an overall reduction in the effectiveness of health systems. One of the main factors that has explained impaired effectiveness and efficiency in hypertension treatment is low adherence to pharmacological treatment. Poor adherence to treatment of hypertension constitutes a huge public health problem and a very important risk factor for complications, disability and hypertension-related mortality.
Overall, majority of the respondents in this study had moderate adherence to antihypertensive medication. However, only a few of the respondents reported 'high' adherence. This contrasts a study conducted in public hospitals in Ethiopia which reported that only one in five patients reported perfect (high) adherence to their antihypertensive treatment regimen. The proportion of patients with high adherence in this study is also lower compared to other studies performed in Ghana (7%) and Nigeria (8%) and those in Palestine (36%), China (52%) and France (50%).,,,, The studies also used MMAS-8, with level of adherence divided into low/medium and high adherence. This finding calls for an intervention among the concerned patients as poor adherence could possibly negate the benefit of antihypertensive medication on cardiovascular outcomes with poor health indices.
A study in Ibadan, Nigeria, found a low rate (35.1%) of medication adherence among hypertensive patients, whereas another study on treatment adherence and BP outcome among hypertensive outpatients in two tertiary hospitals in Sokoto, North-western Nigeria, reported that 54 (8.9%) patients were adherent to medications. Other studies in Nigeria have reported medication adherence of 36.8% and 50.7% among hypertensive patients, whereas medication adherence of 33.3% was reported in a study among hypertensive patients in Ghana and Nigeria.,, Studies in the Democratic Republic of Congo and Eastern Sudan reported adherence of 45.8% and 59.6%, respectively., In another study on adherence to antihypertensive medication in older adults with hypertension, more than half of the respondents (55.9%) acknowledged some degree of medication nonadherence, whereas a study conducted in Isfahan reported 88% complete nonadherence to treatment among patients with hypertension.
However, a review has reported rate of nonadherence to treatment ranging from 12% to 28% among hypertensive patients. When the present study range was compared with this range, the rate of adherence to the treatment was very low. The differences may be due to some factors which include variations in study groups, methods of assessment of adherence and drug schedules.
Mean satisfaction scores with respect to the four domains of effectiveness, side effects, convenience and global satisfaction were 16.2 ± 2.4, 26.2 ± 7.5, 16.8 ± 1.8 and 16.4 ± 2.1, respectively. The overall patient satisfaction score by combining all the four domains was 75.6 ± 10.5, and the higher scores reflect higher satisfaction. Participants with low medication adherence had lower overall satisfaction scores compared to participants with moderate or high medication adherence.
Treatment satisfaction was statistically significantly associated with medication adherence (P < 0.05). This finding shows that treatment satisfaction is a significant determinant of antihypertensive medication adherence. While the exact mechanism through which treatment satisfaction is associated with medication adherence is unknown, our results show that, when patients are more satisfied with the treatment, they are more likely to adhere to the medication regimen. This finding corroborates that of a similar study among an Ethiopian ambulatory patient population and studies from Palestine and Lebanon.,, Studies conducted in Nigeria have also reported an association between patients' satisfaction and medication adherence.,
Limitation of the study
There are some limitations to be considered in the interpretation of our study findings. First, due to the cross-sectional observational study design, we were unable to make causal inferences between medication adherence and patient satisfaction. The association observed may also be bidirectional. Second, medication adherence was based on self-report, which is influenced by recall and social desirability biases and may not have provided a true picture of the actual adherence among the population. There could have been an underestimation or overestimation of the level of adherence reported in the study. Third, we did not measure participants' BP, and hence we do not know if their BP is well controlled or not. Fourth, because the study participants were tertiary clinic based (LUTH), we cannot generalise our study findings to the general community. Lastly, our questionnaire did not capture questions on psychosocial factors which may influence medication adherence and patient satisfaction, thus we cannot rule out residual confounding. This could be investigated in future studies.
| Conclusions|| |
Only one in every hundred patients had high adherence to hypertensive medication in this study, and there was a positive association between treatment satisfaction and medication adherence. Participants with low medication adherence have lower overall satisfaction scores compared to participants with moderate or high medication adherence.
This has an important implication for the hospital management in the improvement of management of patients with hypertension in the hospital. The findings from this study serve as baseline data to aid in the improvement and address the issues of adherence among hypertensive patients in LUTH.
We, therefore, recommend a need for continuous patient-specific adherence education and counselling for hypertensive patients in order to ensure better treatment outcomes.
The authors acknowledge the medical consultants in the cardiology clinics of LUTH and the nurses in charge of the clinic for their support when recruiting the participants for the study. We are also grateful to the medical students who supervised the collection of data.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]