Anti-Hypertensive Medication Adherence and Associated Factors among Adult Hypertensive Patients at Dilla University Referral Hospital, South Ethiopia

Introduction

Hypertension is known as the “silent killer” since it frequently has no warning signs or symptoms, and many people are unaware they have it [1]. Most individuals find out they have it by coincidence when they are hospitalized for an unrelated disease or are exposed to pre-employment or pre-operative medical testing. Although the specific causes of high blood pressure are unknown, a multitude of variables and situations have a part in its development [2]. Medication adherence or compliance is defined as “the act of adhering to the provider’s advice regarding the timing, dosage, and frequency of medication adherence” [3].

As there is no cure for hypertension, patients are expected to take medications for the rest of their lives. Hypertension medication treatment necessitates that patients take their medication exactly as prescribed [4]. Adherence to pharmacological therapy and adaptation to necessary lifestyle adjustments has been found to be particularly effective in hypertension control, with the following benefits for individuals, healthcare systems, and society at large: it improves quality of life and reduces complications and mortality. It is also a cost-cutting approach because it lowers the possibility of complications [5].

Non-communicable diseases (NCDs) are the leading causes of death globally, killing more people each year than all other causes combined [1]. According to World Health Organization reports from 2015 and 2016, NCDs were responsible for 40 million deaths and more than 70% of global mortality, respectively. More than 40% of these deaths could have been avoided by increasing antihypertensive medication adherence, and in low and middle-income countries it account for 80% of NCD deaths [6, 7, 8]. The prevalence of hypertension has increased dramatically in Sub-Saharan Africa over the last two to three decades. The number of adults with hypertension in Sub-Saharan Africa was estimated to be around 80 million in 2000, with a projected increase to 150 million by 2025. Hypertension is one of the most common risk factors for cardiovascular disease in Sub-Saharan Africa (CVD). If nothing is done, by 2020, hypertension would be responsible for three-quarters of all fatalities in Africa [7].

In 2011, the Southern Nations, Nationalities, and Peoples

Region (SNNPR) had a hypertension prevalence of roughly 10% [8].

Adherence is 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 [9, 10].

Therefor this study was sought to identify the prevalence and associated factors among adult hypertensive patients at Dilla General Hospital.

Data Collection Tools and Procedure

Face-to-face interview with a pretested structured questionnaire was conducted to collect the socio- demographics, drug related factors, health care related factors, and patient related characteristics. Face to face interview was employed using two trained clinical nurses, who work at other departments of hospital. Data on co- morbidities, Antihypertensive medication(s) and three isolated BP measurements was extracted from medical records of patients using a pretested data abstraction format. An eight item Morisky’s Medication Adherence Scale was employed to assess the study participant’s medication adherence. It is a self-report questionnaire with a total of 8 items. Items from 1 through 7 are dichotomous based on “Yes” or “No” response. Concerning scoring of these items each ‘No” response was rated as ‘‘1” and each ‘‘Yes” was rated as ‘‘0” except for item 5, in which case, a ‘Yes’ response was rated as ‘‘1” and a ‘‘No” was rated as ‘‘0”. The last item (item8) had a 5-point Liker response choice. The choices were never, once in a while, sometimes, usually, and all of the time. The score for each choice respectively were 1, 0.75, 0.50, 0.25, and 0. The total score of all the 8 items ranges from 0 to 8 points and it can be categorized into three levels of adherence (the cut –off points): ‘high adherence’ (score = 8), ‘medium adherence’ (score of 6 to <8 ), and ‘low adherence’ (score < 6) [10, 14].

Data Quality Control

To maintain validity of data collection tool, structured questionnaire was developed in English and translated to local languages (Amharic and Gedeoffa) and back translated to English. During data collection supervision was carried out by principal investigator. To assure data quality, pretest was conducted; data collectors were recruited; training and orientation was given to data collectors. Completed questionnaires were checked every day after data collection for completeness, clarity and consistency. Any error identified during data entry was corrected after revision of the original completed questionnaire.

Data Processing and Analysis

Data was checked manually for completeness and then coded. Data was entered, cleaned and recorded to analyze using SPSS version 20. Descriptive statistics was used using frequency, percentage, mean and standard deviation. Binary logistic regression statistical modeling was used to identify associated factors. In Bivariable logistic regression, those variables with a p-value <0.25 were candidates for multivariable logistic regression. The association between dependent and independent variables was assessed, and its strength, direction, and significance were presented using odds ratios and 95% confidence intervals. Finally, the result was presented by text, graph, and table.

Operational Definitions

• Hypertension: According to the WHO, hypertension is defined as “a persistent raised systolic or diastolic blood pressure equal to or more than 140/90 mmHg in adults aged 18 years and over” [15].
• Adherence: Is defined 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” and adherence was considered when the patient’s MMAS-8 score is ≥ 6 but Any form of deviation from adherence like losing one appointment, missing doses and when MMAS-8 score was less than 6 was considered non- adherence [9, 10, 16].

• Controlled BP: defined as the achievement of an average three BP readings <140/90 mmHg for age <60 years and <150/90 mmHg for age ≥60 years in individuals being treated for HTN [9, 17].
• Uncontrolled BP: average three BP readings >= 140/90 mmHg for age <60 years and >= 150/90 mmHg for age ≥60 years in individuals being treated for HTN [9, 18].
• Knowledge about Hypertension: Assessed using six-item questions and computing the mean value. Respondents who scored above the mean for the knowledge questions were classified as having good knowledge; otherwise, they did not [12, 19].

• Patient Provider Relationship: Participants who score above the mean for questions prepared on patient provider relationships in the treatment and care of hypertension patients have a good patient-provider relationship; otherwise, they do not [13, 20].

Ethical Consideration

Ethical clearance was obtained from the Research and Ethics Committee Dilla University, college of medicine and health sciences and official letter was obtained from school of medicine prior to data collection. Verbal and written consent was obtained for willingness of patients to participate. The patient’s privacy was maintained by conducting the interview in a private place and they were informed that there won’t be any incentive or harm for their participation in this study. Finally, participant identity was kept anonymous throughout the data collection and analysis process.

Discussion

In many developing nations, ensuring patient adherence to antihypertensive therapy in order to prevent consequences remains a serious public health concern. Poor adherence is the single most major cause of uncontrolled hypertension, severe consequences, and resource waste. Several variables influence a patient’s adherence to medicine [12, 15]. According to this study, 65.3 (58.78–71.82) percent of people take their antihypertensive medication. The result of this study was consistent with a study conducted in Gondar, Debrebirihan, North west Ethiopia, and Shashemene, which was 64.6%, 65.2%, and 63.5%, respectively [12]. Debrebrehan 63.5% Tigist Demisew SM, et al. [16], North west Ethiopia 65.2% Hareri A, et al. [17, 21] and Shashemene 63.5% of respondents were reported [11]. This might be due to similarities in the study settings, the economic status of participants, and the same criteria used for measuring medication adherence (MMAS-8). However, this study reports lower adherence than the study done at Black Lion Hospital in Addis Ababa (69.5%) Tibebu A, et al. [2, 22]. This might be due to better access to care and the provision of quality services in this facility. The findings of this study showed a higher adherence level than Adama’s (59.5%) and Jimma 52.9%) Fiseha G, et al. [19, 23]. This variation could be due to differences in subpopulation and measurement tool (Adama used MMAS4, while at this study setting MMAS 8 was used). Another possible reason could be the high sample size used at Jimma compared to this study area (380 vs. 210) and the high number of participants from rural areas at Jimma compared to the current setting (46% vs. 5.8%), which could be a factor in the low level of education and knowledge gaps regarding hypertension and its treatment. In this study, adherence level was lower than the findings of other studies done at Kenya Mueke AT [5, 24] (74%), South Africa Inkster ME, et al. [20, 25] (76%), and Egypt Youssef RM, et al. [21, 26] (77%). This difference could be due to Variations in the studied populations, better health care and access to health facilities in developed countries, and participants’ better knowledge of hypertension and its treatment in the mentioned countries than in the current study area.

Multivariate logistic regression revealed educational status, duration of therapy, and traditional drug use were factors significantly and inversely associated with antihypertensive medication adherence Akhter N [27, 28, 29, 30].

In this study, participants who can’t read and write (AOR = 0.4, 95% CI = 0.004-0.840) were 60% less likely to adhere to antihypertensive medication when compared to participants who completed college or university level. Similarly, respondents who had a primary school level of education (AOR = 0.50, 95% CI = 0.001-0.194) were 50% less likely to adhere than college or university graduates. The findings of this study were supported by the study report of Nejo, et al. [22, 31] where participants who can’t read and write were 95% less likely to be adherent than college completed and Central Ethiopia Daniel G, et al. [23, 32] which reported respondents who can’t read and write were 65 % less likely to be adherent than university graduates. Studies done at Ghana Agbor VN, et al. [4, 33], Nigeria Iloh GUP, et al. [24, 34] and Zambia [21, 35] showed similar findings. This could be due to low awareness about hypertension, its medications, and its treatment. Patients with a higher education level are expected to have better knowledge about disease and therapies and will thus be more compliant with treatments Roth GA [15, 36].

In this study, duration of diagnosis of hypertension had a significant association with antihypertensive medication adherence. Participants who were diagnosed with hypertension six or more years ago (AOR = 0.280, 95% CI = 0.025–0.836) were 72% less likely to adhere to antihypertensive medications when compared with those diagnosed less than two years ago. This finding was in line with studies done in northwestern Ethiopia Mekonnen HS, et al. [18] Southern Ethiopia Giday A, et al. [8] and Jimma Fiseha G, et al. [19] where respondents with diagnosis of hypertension more than 6 years back were 70%, 73% and 69 % less likely to be adherent to antihypertensive medications than their counter parts respectively. This could be due to patients who were diagnosed many years ago being ageing adults with multiple chronic conditions and polypharmacy, which may adversely affect medication adherence. Such patients are highly vulnerable to alteration in memory, Major depression, and dementia, and thus they could forget their doses. However, in a study done in China by Lee, et al. [25, 37]. Lower adherence was correlated with illness durations shorter than five years. These authors link the better adherence in patients who have lived with the disease longer to their better understanding of the illness, better relationship with the prescribing physician, and greater faith in their physician’s advice. This difference between the studies could be due to variations in socioeconomic settings and the quality of health care service provisions.

Other traditional drug use to treat hypertension is significantly associated with antihypertensive medication adherence. This study revealed that participants who used traditional drugs to treat hypertension (AOR = 0.15, 95% CI = 0.023–0.489) were 85% less likely to adhere to antihypertensive medications than their counterparts. This finding was supported by the report of the study done at Adama Terline DMD, et al. [26], where respondents who used traditional drugs to treat hypertension were 62% less likely to be adherent to medications than those who were diagnosed less than two years back. Similarly, study done China Lee

GKY, et al. [25] where hypertensive patients who did not use traditional drugs to treat hypertension were 5.6 times more likely to be adherent to their antihypertensive medications. Another study done among hypertensive patients in twelve low and middle-income Sub-Saharan countries showed similar findings; accordingly, the odds of adherence among hypertensive patients who used traditional drugs were three times more likely than their counterparts [27, 37].

Conclusion

More than half of study participants were found to be adherent to antihypertensive medications. However, it is found to be significantly lower when compared to expected WHO index of 80% medication adherence. Longer duration of diagnosis of hypertension, Traditional drug use to treat hypertension and being uneducated (can’t read and write) were factors adversely affecting medication adherence. Therefore, routine health education is strongly recommended.

Acknowledgments

We acknowledge Dilla University referral hospital for technical support and study participants for their willingness to participate.

Author’s Contributions

All authors contributed towards drafting manuscript, data analysis and revising the manuscript, gave final approval of the manuscript to be published, and they agreed to be accountable for the all aspects of the manuscript.

Compliances with Ethical Standard

All steps done during data interview were in accordance with ethical review board of Dilla University and Helsinki declaration. The study was approved by Ethical review board of Dilla University College of medicine and health science.

Funding

Non applicable

Disclosure

The authors declare that they have no any conflicts of interest.

Data Sharing Statement

On reasonable request, the corresponding author will provide the datasets used and analyzed during the current work.