LAUSR

475Background: Evidence on economic outcomes could provide insight on comparative economic benefit of TTs. This study assessed all-cause healthcare resource utilization (HRU) and costs among aRCC patients who initiated pazopanib and sunitinib, two commonly-used first TTs. Methods: Pts with aRCC who initiated sunitinib or pazopanib as first TT (index therapy/index date) were identified in this 100% Medicare data + Part D linkage (1/1/2006-12/31/2014). Characteristics were assessed during the 1 year prior to index date (baseline period) and pts were followed until death, end of eligibility, or end of data (study period), whichever was earliest. Pts were stratified by first TT initiated and 1:1 matched using propensity scores based on age, sex, race, year of RCC diagnosis, metastatic sites, comorbidities, and baseline inpatient, outpatient, emergency room, and pharmacy costs. Study period all-cause HRU and costs (2015 USD) were assessed on a per pt per month (PPPM) basis and compared between the matched coho...