Background: The approaching availability of lower-cost generic angiotensin receptor blockers (ARBs) may affect formulary policies for patients maintained on the ARB valsartan.
Objective: Estimate the economic impact of switching from valsartan (including valsartan-based single-pill combinations) to other ARBs without apparent medical reasons.
Research design and methods: Patients with essential hypertension and at least 6 months of continuous valsartan treatment free of hospitalization, cardiovascular events, renal events or ARB-associated adverse events were identified from the MarketScan administrative claims database from January 1, 2004 to March 31, 2008. Those who subsequently switched to a different ARB with at least a 5% copayment decrease (switchers) were matched to those who did not switch (maintainers) according to propensity score quintiles and selected baseline characteristics. Refills were not required after the index fill for the switched-to ARB or maintained valsartan. Matched switchers and maintainers were compared in terms of medication discontinuation, healthcare resource use and costs during the 6 months following the index fill.
Results: A total of 99,926 valsartan maintainers and 2150 switchers (with a mean copayment decrease of $16.5 per month) were identified and matched. After matching, switching from versus maintaining valsartan was associated with an 8% higher risk of medication discontinuation (p < 0.008), 19.1 additional outpatient visits/100 patients (p = 0.002) and 9.3 additional hypertension-related inpatient days/100 patients (p = 0.030). Concurrently, switching from versus maintaining valsartan was associated with higher total medical costs by $748/patient (p < 0.001), driven largely by higher costs for hypertension-related medical services by $492/patient (p = 0.004).
Limitations: Exact reasons for switching were not available and the study assessed only the short-term impacts of switching.
Conclusions: Hypertension patients maintained on valsartan who switched to a different ARB with a lower copayment experienced substantial increases in medication discontinuation, healthcare resource use and costs compared to those who maintained valsartan treatment.