Multiple myeloma (MM) therapy within a Medicare-insured patient population: Role of care setting and oncologist sub-specialization in hematologic malignancies.

Abstract

38 Background: Dramatic increases in oncology practice consolidation with hospitals may affect care setting and whether patients see oncologists that specialize in their cancer, with downstream effects on treatment patterns. This may be particularly true for MM, where approval of new immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs), coupled with evidence supporting PI-IMiD combinations, maintenance (MT), and stem cell transplant (SCT) among fit patients, have expanded options, complexity and lines of therapy (LOT). Methods: We selected adults with MM diagnosis (dx) between 07/07-12/15 from the SEER-Medicare linked database. We required continuous Medicare Parts A and B enrollment and no HMO/PPO coverage from 12 months prior to dx (1 month prior for Part D) through death or end of study (12/16) and MM therapy initiation w/in 12 months post dx. Outcomes including LOT1 PI-IMiD combination, SCT, MT, and any LOT2, 3 or 4 were constructed using claims indicators for oral and IV drugs and receipt dates. Provider setting was assigned as academic and/or NCI cancer center, non-teaching hospital, or community (non-hospital) based on the most recent oncologist E and M visit prior to LOT1 initiation. Percentage of patient panel with hematologic malignancies (Heme%) was calculated for each oncologist, using a pooled sample of 11 major cancer sites reported in SEER-Medicare. Multivariable logistic regressions included care setting, %Heme, with controls for demographics, health status, and diagnosis year. Results: The cohort (n = 4930) was 14% Black, and 51% age ≥75 years. Care setting was 23% academic, 14% non-teaching hospital, and 63% community; community setting decreased from 72 to 58% during observation period (2007 to 2015). Mean Heme% (31% overall) was higher in academic hospitals (44%) compared with community practices (27%; p < .001). LOT1 PI-IMiD, LOT 2, 3 and 4 were received by 21%, 55%, 31% and 18% respectively, with 53% MT, and 7% SCT. Higher %Heme was associated with increased likelihood of LOT1 PI-IMiD, SCT, LOT3, and LOT4. Relative to academic/NCI, community care was associated with higher adjusted odds for LOT1 PI-IMiD: aOR 1.33, p < .001; but lower odds for any LOT4: aOR .67, p = .001). Conclusions: Using a novel measure of oncologist sub-specialization in hematologic malignancies, we found positive associations with receipt of initial PI-IMiD therapy and ongoing LOTs in a Medicare insured population treated for MM. Surprisingly, care in a community setting was associated with recommended initial PI-IMiD therapy, but fewer LOTs.