Association of Hospital Volume and Quality of Care with Survival for Ovarian Cancer

OBJECTIVE: To assess whether strict adherence to quality metrics by hospitals could explain the association between hospital volume and survival for ovarian cancer. METHODS: We used the National Cancer Database to perform a retrospective cohort study of women with ovarian cancer from 2004 to 2013. Hospitals were stratified by annual case volume into quintiles (2 or less, 2.01-5, 5.01-9, 9.01-19.9, 20 cases or greater) and by adherence to ovarian cancer quality metrics into quartiles. Hospital-level adjusted 2- and 5-year survival rates were compared based on volume and adherence to the quality metrics. RESULTS: A total of 100,725 patients at 1,268 hospitals were identified. Higher volume hospitals were more likely to adhere to the quality metrics. Both 2- and 5-year survival increased with hospital volume and with adherence to the measured quality metrics. For example, 2-year survival increased from 64.4% (95% CI 62.5-66.4%) at low-volume to 77.4% (95% CI 77.0-77.8%) at high-volume centers and from 66.5% (95% CI 65.5-67.5%) at low-quality to 77.3% (95% CI 76.8-77.7%) at high-quality hospitals (P<.001 for both). For each hospital volume category, survival increased with increasing adherence to the quality metrics. For example, in the lowest volume hospitals (two or less cases annually), adjusted 2-year survival was 61.4% (95% CI 58.4-64.5%) at hospitals with the lowest adherence to quality metrics and rose to 65.8% (95% CI 61.2-70.8%) at the hospitals with highest adherence to the quality metrics (P<.001). However, lower volume hospitals with higher quality scores still had survival that was lower than higher volume hospitals. CONCLUSION: Although both hospital volume and adherence to quality metrics are associated with survival for ovarian cancer, low-volume hospitals that provide high-quality care still have survival rates that are lower than high-volume centers.