Socio-demographic and clinical factors affecting adherence to antihypertensive medications and blood pressure control among patients attending the family practice clinic in a tertiary hospital in northern Nigeria

Abstract

Background: The prevalence of hypertension is high while the level of blood pressure control is low in developing countries such as Nigeria. Nonadherence to antihypertensive medication is a very important factor affecting effective blood pressure control. Unfortunately, the level of adherence to antihypertensive medication is also generally low. Non- adherence to antihypertensive medication therefore poses a great challenge to the management of hypertension in Nigeria.

Methods: The objective of the study was to assess the factors affecting adherence to antihypertensive medication in patients attending the Family Practice Clinic of Ahmadu Bello University Teaching Hospital, Zaria, (ABUTH, Zaria) in order to improve management outcomes.

A hospital- based cross- sectional study was carried out on 302 hypertensive patients at the Family Practice Clinic of ABUTH, Zaria who had been on antihypertensive drugs for at least one month. Adherence was measured with the Morisky- Green Medication Adherence Scale (MMAS- 8), with a score of greater than 2 being non-adherent and a score of 0-2 being adherent. A patient was said to have achieved blood pressure control if the blood pressure was < 140/90mmHg. A structured interviewer-administered questionnaire was used to assess the socio-demographic and clinical profile of respondents. The blood pressure, weight and height were measured with standardized instruments and their body mass index was calculated.

Results: Adherence to antihypertensive medication and blood pressure control rates were 52.6% and 36.1% respectively. Independent predictors of adherence were religion (OR= 0.547, p= 0.03, CI= 0.317- 0.943), duration of diagnosis of hypertension (OR=0.283, p= 0.043, CI= 0.084-0.059), duration of taking antihypertensive medication between 1-10 years (OR= 7.241, p= 0.033, CI= 0.955-54.896) and taking > 3 types of antihypertensive medication ( OR= 0.242, p= 0.033, CI= 0.066-0.891). Blood pressure control and family functionality were also associated with adherence to antihypertensive medication although the association was not statistically significant.

Conclusion: In this study, it was found that the proportion of adherence and blood pressure control was low and the identified factors associated with poor adherence were religion, duration of diagnosis, duration of taking medication, taking greater than three drugs and family dysfunction. Therefore continuous adherence counseling should be done to hypertensive patients with these identified factors in order to improve adherence, blood pressure control and ultimately cardiovascular morbidity and mortality.

Keywords: hypertension, medication adherence, blood pressure control, socio demographic factors, clinical factors