Abstract
BACKGROUND: The share of oncology practices owned by hospitals (ie, vertically integrated) nearly doubled from 2007 to 2017. We examined how integration between hospitals and oncologists affected care quality, outcomes, and spending among metastatic castration-resistant prostate cancer (mCRPC) patients. METHODS: Using Surveillance, Epidemiology, and End Results-Medicare linked data and the Medicare Data on Provider Practice and Specialty, we identified Medicare beneficiaries who initiated systemic therapy for mCRPC between 2008 and 2017 (n = 9172). Primary outcomes included 1) bone-modifying agents (BMA) use, 2) time on systemic therapy, 3) survival, and 4) Medicare spending for the first 3 months following therapy initiation. We used a differences-in-differences approach to estimate the impact of vertical integration on outcomes, adjusting for patient and provider characteristics. RESULTS: The proportion of patients treated by integrated oncologists increased from 28% to 55% from 2008 to 2017. Vertical integration was associated with an 11.7 percentage point (95% confidence interval [CI] = 4.2 to 19.1) increased likelihood of BMA use. There were no satistically significant changes in time on systemic therapy, survival, or total per-patient Medicare spending. Further decomposition showed an increase in outpatient payment ($5190, 95% CI = $1451 to $8930) and decrease in professional service payment (-$4757, 95% CI = -$7644 to -$1870) but no statistically significant changes for other service types (eg, inpatient and prescription drugs). CONCLUSIONS: Vertical integration was associated with statistically significant increased BMA use but not with other cancer outcomes among mCRPC patients. For oncologists who switched service billing from physician offices to outpatient departments, there was no statistically significant change in overall Medicare spending in the first 3 months of therapy initiation. Future studies should extend the investigation to other cancer types and patient outcomes.