Quality of care and attributable healthcare costs in diabetic hypertensive patients initiated on calcium antagonist therapy

Background and objective: Calcium antagonists (CAs) from two classes - dihydropyridine and non-dihydropyridine (DCAs and NDCAs, respectively) - are important add-on agents in goal blood pressure (BP) attainment. This study compared drug regimens to which DCAs or NDCAs had been added; for each class, BP reduction and healthcare costs were evaluated in a diabetic hypertensive population. Design, setting and patients: This was a retrospective observational study using administrative claims data within two US health plans. Patients with diabetes mellitus (DM) and hypertension initiated on CA therapy between 1 January 2000 through 30 June 2002 were identified; the date the first CA prescription (CA-Rx) was filled in this period was labelled the index date. Inclusion required plan enrolment for 6 months pre- and 1 year post-index, no CA-Rx 6 months pre-index, and medication possession ratio >50% for 1 year post-index. Patients fell into either dihydropyridine or non-dihydropyridine study groups. Main outcome measures and results: For each group, costs (amounts allowed by plans, in US dollars; actual costs for 2000-2002) were calculated for resources attributable to DM/hypertension. A total of 5551 patients met eligibility criteria (NDCA = 1515; DCA = 4036). Most had been taking other antihypertensive I medications: 86% and 76% in the DCA and NDCA groups, respectively. The NDCA group had lower annual attributable costs than the DCA group ($US1637 [95% CI $US1479, $US1813] vs $US1989 [95% CI $US1823, $US2170]; p <0.004). A total of 313 medical charts were reviewed (DCA = 242, NDCA = 71). Both groups had similar pre-and post-index BP values; mean changes in systolic and diastolic BP were not statistically significant between groups. Only 22% of all patients attained the recommended systolic/diastolic BP goal of