Fixed Dose Combination Therapy and Best Adherence in Patients with Hypertension

San Francisco—An analysis of medical and pharmacy claims from a health plan found that patients with hypertension who took fixed dose combinations had better adherence rates compared with patients who took loose dose combination therapy. The combination of amlodipine and olmesartan (AML/OM) was the combination treatment associated with the best adherence.

The results were presented at the AMCP meeting in a poster titled Adherence and Medical Cost Patterns of Treatment with RAS Inhibitor/Amlodipine Combinations.

The authors indicated 65 million people in the United States have hypertension, but approximately 50% are inadequately managed. In 2010, costs associated with hypertension were estimated at >$76 billion ($54.9 billion direct and $21.7 billion indirect), with the costs of uncontrolled hypertension adding to the burden.

In this study, the authors examined a database from a large US managed care plan that included data on medical and pharmacy claims from approximately 31 million patients covered by commercial insurance or Medicare Part D. Patients were included if they had a primary or secondary diagnosis of hypertension and a first pharmacy claim indicating they were treated with fixed dose AML/OM, fixed dose AML/benazepril (AML/BEN), and loose dose AML/angiotensin receptor blocker (AML/ARB). The authors defined loose dose as 2 pharmacy claims in which the days supplied for the 2 active ingredients overlapped.

Other inclusion criteria included continuous enrollment for 6 months prior to and ≥1 year after the index date during the analysis time period (between March 1, 2007, and December 31, 2009). Patients could not be pregnant, in labor, or deliver a baby during the study period.

There were 24,663 people in the study; 48.9% were in the fixed dose AML/BEN group, 31.4% were in the loose dose AML/ARB group, and 19.7% were in the fixed dose AML/OM group. Patients in the fixed dose AML/OM group (53.8 years of age) and fixed dose AML/BEN group (56.0 years of age) were significantly younger than the loose dose AML/ARB group (60.7 years of age).

The authors found that 44.12% of patients in the fixed dose AML/OM group were adherent to the medication, which was significantly higher than the fixed dose AML/BEN group (36.46%) and the loose dose AML/ARB group (19.53%) (P<.001 for both comparisons). They measured adherence as the proportion of days covered (PDC), which was defined as the number of days of therapy with the medication during the follow up period divided by the number of follow up days. Patients with a PDC ≥0.8 were considered to have high adherence, while a PDC ≤0.8 was considered suboptimal adherence.

In addition, compared with the AML/OM group, healthcare resource use was significantly higher in the other 2 groups. Also, except for hypertension attributable pharmacy costs, healthcare costs were significantly higher in the AML/BEN and loose dose AML/ARB groups compared with the AML/OM group.

Similar to other studies, adherence rates were low in this analysis, according to the authors. However, they determined that better adherence was associated with lower costs and lower healthcare utilization.

Among the limitations cited the authors indicated that filling a prescription does not necessarily equate to adherence, although they said studies typically use claims data to measure adherence. Another limitation of claims data is that they imply an association rather than causation. Finally, the authors noted there might have been selection bias.

This study was supported by Janssen Scientific Affairs, LLC.