Pharmacoepidemiology of antihypertensive drugs in primary care setting of Bahrain between 1998 and 2000

PURPOSE: To compare pattern of antihypertensive drug utilization in 1998 with 2000 following the: (a) publication of 1999 World Health Organization/International Society of Hypertension (WHO/ISH) guidelines for drug management of hypertension; and (b) introducing new antihypertensives to the essential drug list, in primary care, Bahrain. METHODS: Retrospective prescription-based survey carried out in seven out of 20 primary care health centers in Bahrain. A total of 9272 patients comprising 6543 with uncomplicated hypertension and 2729 with diabetic hypertension were studied. RESULTS: Between 1998 and 2000, the prescription rate of beta-blockers and methyldopa significantly declined (p < 0.0001) while the rate of angiotensin converting enzyme (ACE) inhibitors and calcium channel blockers (CCBs) increased (p < 0.0001) in uncomplicated hypertension. However, in diabetic hypertension there was a non-significant decline in utilization of beta-blockers, CCBs, methyldopa, and diuretics whereas a significant increase in prescribing of ACE inhibitors (p < 0.0001). Inclusion of Perindopril into the essential drug list resulted in an overall increase in utilization of ACE inhibitors: use of captopril and enalapril declined while lisinopril and perindopril increased. Substitution of immediate-release (IR) indapamide by sustained-release (SR) formulation did not change the overall utilization of diuretics; however, intra-class changes were evident with a significant decline in use of thiazide diuretics and concomitant increase in use of SR indapamide by 2000. CONCLUSIONS: The antihypertensive prescribing pattern is influenced by WHO/ISH guidelines as well as by introduction of new antihypertensives to primary care essential drug list in primary care. The choice of a drug is also influenced by presence of co-morbidity with diabetes mellitus.