A Risk-Adjusted Model for Ovarian Cancer Care and Disparities in Access to High-Performing Hospitals

OBJECTIVE: To validate the observed/expected ratio for adherence to ovarian cancer treatment guidelines as a risk-adjusted measure of hospital quality care, and to identify patient characteristics associated with disparities in access to high-performing hospitals. METHODS: This was a retrospective population-based study of stage I–IV invasive epithelial ovarian cancer reported to the California Cancer Registry between 1996 and 2014. A fit logistic regression model, which was risk-adjusted for patient and disease characteristics, was used to calculate the observed/expected ratio for each hospital, stratified by hospital annual case volume. A Cox proportional hazards model was used for survival analyses, and a multivariable logistic regression model was used to identify independent predictors of access to high-performing hospitals. RESULTS: The study population included 30,051 patients who were treated at 426 hospitals: low observed/expected ratio (n=304) 23.5% of cases; intermediate observed/expected ratio (n=92) 57.8% of cases; and high observed/expected ratio (n=30) 18.7% of cases. Hospitals with high observed/expected ratios were significantly more likely to deliver guideline-adherent care (53.3%), compared with hospitals with intermediate (37.8%) and low (27.5%) observed/expected ratios (P<.001). Median disease-specific survival time ranged from 73.0 months for hospitals with high observed/expected ratios to 48.1 months for hospitals with low observed/expected ratios (P<.001). Treatment at a hospital with a high observed/expected ratio was an independent predictor of superior survival compared with hospitals with intermediate (hazard ratio [HR] 1.06, 95% CI 1.01–1.11, P<.05) and low (HR 1.10, 95% CI 1.04–1.16, P<.001) observed/expected ratios. Being of Hispanic ethnicity (odds ratio [OR] 0.85, 95% CI 0.78–0.93, P<.001, compared with white), having Medicare insurance (OR 0.74, 95% CI 0.68–0.81 P<.001, compared with managed care), having a Charlson Comorbidity Index score of 2 or greater (OR 0.91, 95% CI 0.83–0.99, P<.05), and being of lower socioeconomic status (lowest quintile OR 0.41, 95% CI 0.36–0.46, P<.001, compared with highest quintile) were independent negative predictors of access to a hospital with a high observed/expected ratio. CONCLUSION: Ovarian cancer care at a hospital with a high observed/expected ratio is an independent predictor of improved survival. Barriers to high-performing hospitals disproportionately affect patients according to sociodemographic characteristics. Triage of patients with suspected ovarian cancer according to a performance-based observed/expected ratio hospital classification is a potential mechanism for expanded access to expert care.