Poor adherence to medication and salt restriction as a barrier to reaching blood pressure control in patients with hypertension: Cross-sectional study from 12 sub-Saharan countries

Abstract

Background: Sub-Saharan Africa is experiencing a rising burden of hypertension. Antihypertensive medications and diet are the cornerstone of effective hypertension control.

Aims: To assess adherence to medication and salt restriction in 12 sub-Saharan countries, and to study the relationship between adherence and blood pressure control in patients with hypertension.

Methods: We conducted a cross-sectional survey in urban clinics in twelve sub-Saharan countries. Data were collected on demographics, treatment and adequacy of blood pressure control in patients with hypertension attending the clinics. Adherence was assessed by questionnaires completed by the patients. Hypertension grades were defined according to European Society of Cardiology guidelines. Association between adherence and blood pressure control was investigated using multilevel logistic regression analysis, adjusting for age, sex and country.

Results: Among the 2198 patients, 77.4% had uncontrolled blood pressure, 34.0% were poorly adherent to salt restriction, 64.4% were poorly adherent to medication and 24.6% were poorly adherent to both. Poor adherence to salt restriction (odds ratio [OR] 1.33, 95% confidence interval [CI] 1.03-1.72), medication (OR 1.56, 95% CI 1.25-1.93) or both (OR 1.91 1.39-2.66) was related to uncontrolled blood pressure. Moreover, poor adherence to both medication and salt restriction was related to a 1.52-fold (95% CI 1.04-2.22), 1.8-fold (95% CI 1.22-2.65) and 3.08-fold (95% CI 2.02-4.69) increased likelihood of hypertension grade 1, 2 and 3, respectively.

Conclusions: High levels of poor adherence to salt restriction and medication were noted in this urban sub-Saharan study; both were significantly associated with uncontrolled blood pressure, representing major opportunities for intervention to improve hypertension control in sub-Saharan Africa.

Keywords: Adhérence; Afrique Subsaharienne; Epidemiology; Global health; Hypertension; Medication adherence; Sub-Saharan Africa; Épidémiologie.