Abstract 3309: Healthcare resource utilization in follicular lymphoma patients treated with maintenance rituximab in the Veterans Health Administration

OBJECTIVES: Examine healthcare resource utilization (HCRU) in follicular lymphoma (FL) patients treated with or without maintenance rituximab (MR). METHODS: FL patients treated in the Veterans Health Administration (VHA) between 2006-2014 were identified by linking information from the VA Cancer Registry System (VACRS) and the Corporate Data Warehouse. HCRU was defined as the total number of outpatient visits (OPV), inpatient visits (IPV), and the number of emergency department visits (EDV) during follow-up time, which was approximately four years. To avoid immortal time bias, a prescription time distribution matching method was performed, followed by an inverse probability weighted regression analysis to account for variation in the follow-up period. The observational period was partitioned into four-yearly intervals. The observed HCRU value was weighted by the inverse of the probability of not being censored by the end of the yearly interval. A generalized linear model with Poisson distribution and log link was performed for each of the four intervals while adjusting for the covariates. Using a 95% bootstrap confidence interval, the change of HCRU was summed across the four-yearly intervals to obtain the cumulative change of HCRU between FL patients who received MR or did not receive MR. RESULTS: From 2006-2014, 2,290 FL patients were diagnosed at VHA. After excluding patients with a prior cancer, documented grade 3b or stage I disease, 905 MR-eligible patients remained, of which 319 (35%) received MR and 586 (65%) did not receive MR. When compared with non-MR patients, MR patients were slightly more likely to have a mean increase in OPV (0.69%; CI: 0.44%-0.94%) and a mean decrease in IPV (14.83%; CI: 16.09%-13.58%). There was no significant change in the number of EDV between the MR treated and non-MR treated patients. CONCLUSIONS: This nationwide real-world study suggests that on average FL patients treated with MR have fewer IPV and more OPV than non-MR patients. Note: This abstract was not presented at the meeting. Citation Format: Ahmad S. Halwani, Catherine Li, Kelli M. Rasmussen, Vikas Patil, Christina Yong, Zachary Burningham, Brian C. Sauer. Healthcare resource utilization in follicular lymphoma patients treated with maintenance rituximab in the Veterans Health Administration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3309.