The Nigerian antihypertensive adherence trial

Abstract

Research in industrialized countries has demonstrated that a key factor limiting the control of hypertension is poor patient adherence and that the most successful interventions for long-term adherence employ multiple strategies. Very little data exist on this question in low-income countries, wherein medication-taking behavior may be less well developed. We conducted a treatment adherence trial of 544 patients [mean age ∼63 years, mean blood pressure (BP) ∼168/92 mmHg] with previously untreated hypertension in urban and rural Nigeria. Eligible participants were randomized to one of two arms: clinic management only, or clinic management and home visits. Both interventions included three elements: a community based, nurse-led treatment program with physician backup; facilitation of clinic visits and health education; and the use of diuretics and a β blocker as needed. After initial diagnosis, the management protocol was implemented by a nurse with physician backup. Participants were evaluated monthly for 6 months. Medication adherence was assessed with pill count and urine testing. Drop-out rates, by treatment group, ranged from 12 to 28%. Among participants who completed the 6-month trial, overall adherence was high (∼77% of participants took >98% of prescribed pills). Adherence did not differ by treatment arm, but was better at the rural than the urban site and among those with higher baseline BP. Hypertension control (BP <140/90 mmHg) was achieved in approximately 66% of participants at 6 months. This community-based intervention confirms relatively modest default rates compared with industrialized societies, and suggests that medication adherence can be high in developing world settings in clinic attenders.