A therapeutic audit in the management of hypertension in Nigerians

The prevalence of hypertension in adult Nigerians is about 20% and hypertension remains a significant risk factor in cardiovascular morbidity and mortality. In Africans, hypertension carries a dismal prognosis, has a late clinical presentation and certain antihypertensives may be less effective. We therefore conducted a therapeutic audit in order to assess the initial cardiovascular risk profile of Nigerian patients as well as the safety and efficacy of different antihypertensive agents. A cross-sectional survey of 367 patients (M:F:2:1) modal age 25-44 years, mostly WHO II, enrolled in our clinic was undertaken. 56% had been on treatment for up to one year and 2% for longer than ten years. 12.5% had concomitant diabetes mellitus. Statistical analyses of drug efficacy were done by Spearman correlation and Analysis of Variance (ANOVA). The rank order of hypertensive efficacy was as follows: Thiazides (T) (r = 0.57, P less than 0.05), T + Methyldopa (M) (r = 0.91, P less than 0.001) T + M + Hydralazine (r = 0.92, P less than 0.001). Neither propranolol, nor frusemide showed significant overall efficacy. However, propranolol appeared efficacious in hypertensives with renal impairment. Postural dizziness was occasionally reported. Total mortality was 6% occurring mostly in the modal age group. Diabetic hypertensives had a 5 fold enhanced risk of a fatal outcome (X2 P less than 0.001). Our findings support a rational stepped care approach to pharmacotherapy of hypertension in black Africans, a cost-effectiveness analysis of common antihypertensives; it elucidates the associated adverse effects to patients, and draws attention to the lethality of concomitant hypertension and diabetes. Prospective large scale studies of the treatment of hypertension in Africans are required.