Effect of pharmaceutical formulation for antihypertensive therapy on health service utilization.

A significant factor in the management of hypertension is the extent to which patients comply with the treatment regimen. A retrospective analysis was undertaken to determine the relationship between antihypertensive formulation, regimen compliance, and the utilization of health care services. Data for this analysis were derived from the state of South Carolina's Medicaid computer archive. The study population consisted of 1000 randomly selected patients initially prescribed one of the following antihypertensive regimens as monotherapy: atenolol once daily, captopril BID, oral clonidine BID, transdermal clonidine once weekly, diltiazem BID, enalapril BID, metoprolol BID, prazosin BID, terazosin once daily, and sustained-release verapamil once daily. Multivariate regression analysis was used to determine the incremental influence of selected demographic characteristics, use of medical services before diagnosis of hypertension, initial antihypertensive medication, medication possession ratio for antihypertensive therapy, and number of maintenance medications for diseases other than hypertension on post-period health care expenditures. The results indicated that patients initially prescribed antihypertensive medication requiring once-daily or once-weekly administration experienced an increased utilization of antihypertensive medication, needed fewer changes in their therapeutic regimen, and far less need for concomitant therapy for blood pressure control compared with those prescribed a BID regimen. Patients in the once-daily or once-weekly groups also used significantly fewer physician, hospital, and laboratory services (P < or = 0.05).