Patterns of utilization of antihypertensive drug combinations in Bahrain: do they conform with international guidelines?

OBJECTIVES

To explore the prescribing pattern and rationale of antihypertensive combination drug therapy at the level of primary health care centers; and to analyze the extent of physicians' adherence to dosage range of antihypertensives in combination regimens as recommended by Guidelines Subcommittee of WHO/ISH 1999.

SUBJECTS, MATERIAL AND METHODS: A prescribing survey of antihypertensive combination regimens among patients with uncomplicated essential hypertension was conducted in 7 out of a total of 18 health centers in Bahrain. The relevant data for our study was collected using cards designed for chronically ill patients.

RESULTS

A total of 2414 hypertensive patients (62.9%), of a 3838 study population, were on monotherapy, whereas 1414 (37.1%) were on antihypertensive combination therapy. Among those who were treated with drug combinations, 85.1% (n = 1212) received two-drug, 14.2% (n = 202) received three-drug and four- and five-drug regimens were used by 0.6% and 0.07%, respectively. Prescription analysis revealed that 17 different two- and three-antihypertensive drug combinations were prescribed for each category. The four major two-drug regimens were ranked in the following order: a beta-blocker with a diuretic (40.4%) used more frequently in females than in males (p < 0.0001), a beta-blocker with a calcium channel blocker (19.7%), a beta-blocker with an ACE inhibitor (12.8%) and a diuretic with an ACE inhibitor (7.3%) - used more frequently in males than in females (p = 0.001, 0.01, and 0.028, respectively). The most frequently prescribed three-drug regimens were diuretic and a beta-blocker plus either an ACE inhibitor (30.7%) or a calcium channel blocker (22.3%), beta-blocker plus an ACE inhibitor and a calcium channel blocker (16.3%), and a diuretic plus an ACE inhibitor and a calcium channel blocker (11.4%). There was no gender-related difference among triple-drug regimens. There was a trend towards using high doses of the beta-blocker atenolol, ACE inhibitors and methyldopa.

CONCLUSION

The prescribing patterns of some practising physicians were analyzed in terms of conformity with guidelines of combination of drugs and dosages. The use of antihypertensive combination therapy and the doses of individual drugs in combination regimens seem to be partly non-compliant with guidelines issued by WHO recommendations; this is illustrated by excessive prescription of some irrational combinations, as well as limited prescription of some rational combinations. In addition, a tendency to use high doses of certain classes of antihypertensive combinations was observed.