Persistence and Compliance Among US Patients Receiving Pazopanib or Sunitinib as First-Line Therapy for Advanced Renal Cell Carcinoma: A Retrospective Claims Analysis

BACKGROUND: For first-line therapy options for advanced renal cell carcinoma (KC), clinical trials have demonstrated similar efficacy for pazopanib and sunitinib as well as differing side-effect profiles, which may affect patient persistence in self-administration of these oral medications. However, the treatment patterns of each drug in real-world clinical practice, as opposed to the controlled environment of a trial, have not been directly compared. OBJECTIVE: To compare persistence and compliance (adherence) with pazopanib versus sunitinib in a real-world setting. METHODS: This was a retrospective claims analysis using 2 databases: Optum Research Database and Impact National Benchmark Database. Eligible patients included adult patients (aged >= 18 years) with >= 2 RCC diagnoses and evidence of first-line therapy with >= 1 subsequent pharmacy claim for pazopanib or sunitinib between October 2009 and July 2012. The date of the first pazopanib or sunitinib claim was defined as the index date. Additional requirements included continuous enrollment in the health plan for 2 months prior (baseline period) through 6 months after (follow-up period) the index date and no cancers other than those associated with RCC. Propensity score matching was used to minimize selection bias. Persistence with the index drug was compared using days to discontinuation, estimated level of persistence (ELPT) at 180 days, and proportion of days covered (PDC). PDC was defined by dividing the number of days covered with the index drug by the number of follow-up days. Compliance was estimated using medication possession ratio (MPR). For matched cohort pairs with >1 fill, MPR was defined by dividing the number of days covered with the index drug by the number of days between the first and last index medication fill. RESULTS: We identified 84 matched pairs among 97 patients prescribed pazopanib and 349 prescribed sunitinib. Among the matched population, mean comorbidity index score was 5.8(95% Cl=1.8-6.0) for pazopanib, and 6.1 (95% CI=1.8-6.0) for sunitinib (P=0.133). Evidence of any radiation therapy during the baseline period was significantly higher among the sunitinib cohort prior to matching (9% vs. 18%, P=0.043), and evidence of surgery was higher in the pazopanib cohort after matching (12% vs. 7%, P=0.046). Cohorts were balanced according to demographic and clinical characteristics with mean (SD) age of 63.0 (9.0) years and 77.4% male. During the 6-month period after drug initiation, there was no significant difference (P>0.05) by drug cohort in the duration of index drug therapy or the percentage of patients who discontinued their index drugs. The mean (SD) time to discontinuation was 133.4 (62.8) days and 139.9 (55.6) days among the matched pazopanib and sunitinib cohorts, respectively (P=0.445). In both cohorts, more than 40% of patients discontinued their index drugs (46.4% pazopanib and 44.1% sunitinib, P=0.732). In addition, there was no significant difference by drug cohort in the ELPT at any time examined between 30 and 180 days after initiation of therapy. PDC with the index drug during the fixed 6-month follow-up was also examined. Although the mean PDC was significantly higher among the sunitinib cohort (0.77 vs. 0.68 for pazopanib, P=0.037), there was no difference by cohort in the percentage of patients with high PDC (defined as 80%): 52.4% versus 56.0% for pazopanib and sunitinib, respectively (P=0.622). Mean MPR among matched pairs with at least 2 fills for the index drug was significantly higher among the sunitinib cohort, although there was no difference by cohort in the percentage of patients with high MPR (defined as a 80%): 81.4% versus 93.2% for pazopanib and sunitinib, respectively (P>0.071). CONCLUSIONS: In the first 6 months of treatment, persistence and compliance to pazopanib and sunitinib were similar. Future studies are needed, including those assessing larger cohorts and longer follow-up periods. Copyright (C) 2015, Academy of Managed Care Pharmacy. All rights reserved.