Antihypertensive medication compliance in a Veterans Affairs Healthcare System

To compare compliance rates associated with categories of antihypertensive medications in a Veteran's Affairs (VA) Healthcare System by use of readily available data and standard software.

Prescriptions from the Veteran's Health Information System Technology Architecture (VISTA) database for angiotension-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), beta-blockers, calcium-channel blockers (CCBs), diuretics, and a miscellaneous group of antihypertensives filled or refilled during a 12-month period were included in the analysis. Claims data for each prescription were exported from the VISTA database to Microsoft Excel, and compliance rates were calculated by use of a methodology reported elsewhere. Mean compliance rates for each antihypertensive category were compared.

A total of 26 201 prescription records accounting for 51 927 separate prescription fills or refills were included. The majority of prescriptions (77%) were associated with calculated compliance rates >80%. The CCB category was associated with a significantly higher compliance rate (p < 0.001) than the beta-blockers (95% CI 1.3% to 3.7%), diuretics (95% CI 1.4% to 3.8%), and miscellaneous agents (95% CI 1.7% to 7.5%). The ACE inhibitor category was associated with a significantly higher rate (p < 0.001) than the beta-blockers (95% CI 0.7% to 3.0%), diuretics (95% CI 0.7% to 3.0%), and miscellaneous agents (95% CI 1.1% to 6.8%). The ARB category had a higher compliance rate (p < 0.001) than the miscellaneous category (95% CI 1.2% to 11.9%). There were no significant differences in compliance rates among ACE inhibitors, CCBs, or ARBs.

VA outpatients are relatively compliant when taking their antihypertensive medications as measured by prescription refill rates. Compliance rates for CCBs and ACE inhibitors are higher than those for beta-blockers, diuretics, and agents such as clonidine, methyldopa, hydralazine, and reserpine. Compliance for ARBs compared favorably with those of CCBs and ACE inhibitors. The methods used in this evaluation can be easily implemented at other institutions as part of ongoing medication compliance improvement efforts.