Pharmacoepidemiological Determinants of Antihypertensive Treatment Intensification in Hypertensive Patients with Uncontrolled Blood Pressure across Six Nigerian Geopolitical Zones

Background: Clinical inertia, defined as failure to intensify treatment when therapeutic targets are not met, is a major contributor to poor blood pressure control in Nigeria. A national pharmacoepidemiological investigation identifying determinants of treatment intensification across all geopolitical zones would provide evidence for targeted interventions. This study characterises treatment intensification patterns and determinants in hypertensive patients with uncontrolled blood pressure across Nigeria. Methods: A multi-site cross-sectional pharmacoepidemiological study was conducted at 24 hypertension clinics representing all six geopolitical zones (four sites per zone). Data from 1,440 hypertensive patients with documented uncontrolled blood pressure at the most recent visit were extracted. Treatment intensification in the 12-month preceding period was defined by a new drug addition, dose increase, or drug class change. Multilevel logistic regression assessed patient and facility-level determinants. Results: Treatment was intensified in only 39 percent of encounters where blood pressure was uncontrolled. Intensification rates varied significantly by zone, highest in South West (52%) and lowest in North East (27%). Patient-level predictors included younger age (OR 1.6), diabetes comorbidity (OR 1.8), and pharmacist clinic attendance (OR 2.1). Facility-level predictors included presence of a hypertension protocol (OR 3.4) and specialist staffing (OR 2.2). Conclusion: Clinical inertia in hypertension management is prevalent across Nigeria with significant zonal variation. Structured treatment intensification protocols and pharmacist co-management models are key modifiable determinants. Keywords: pharmacoepidemiology, hypertension, treatment intensification, clinical inertia, Nigeria