Observed-to-expected ratio for adherence to treatment guidelines as a quality of care indicator for ovarian cancer

- Adherence to NCCN guidelines is correlated with improved survival and is a useful measure of quality cancer care.
- Treatment at high O/E hospitals is associated with significant improvement in ovarian cancer-specific survival.
- Development of a quality metric combining case volume with a quality process measure is feasible and predicts survival.

ObjectiveTo develop an observed-to-expected ratio (O/E) for adherence to National Comprehensive Cancer Network (NCCN) ovarian cancer treatment guidelines as a risk-adjusted hospital measure of quality care correlated with disease-specific survival.MethodsConsecutive patients with stages I-IV epithelial ovarian cancer were identified from the California Cancer Registry (1/1/96-12/31/06). Using a fit logistic regression model, O/E for guideline adherence was calculated for each hospital and distributed into quartiles stratified by hospital annual case volume: lowest O/E quartile or annual hospital case volume < 5, middle two O/E quartiles and volume ≥ 5, and highest O/E quartile and volume ≥ 5. A multivariable logistic regression model was used to characterize the independent effect of hospital O/E on ovarian cancer-specific survival.ResultsOverall, 18,491 patients were treated at 405 hospitals; 37.3% received guideline adherent care. Lowest O/E hospitals (n = 285) treated 4661 patients (25.2%), mean O/E = 0.77 ± 0.55 and median survival 38.9 months (95%CI = 36.2-42.0 months). Intermediate O/E hospitals (n = 85) treated 8715 patients (47.1%), mean O/E = 0.87 ± 0.17 and median survival of 50.5 months (95% CI = 48.4-52.8 months). Highest O/E hospitals (n = 35) treated 5115 patients (27.7%), mean O/E = 1.34 ± 0.14 and median survival of 53.8 months (95% CI = 50.2-58.2 months). After controlling for other variables, treatment at highest O/E hospitals was associated with independent and statistically significant improvement in ovarian cancer-specific survival compared to intermediate O/E (HR = 1.06, 95% CI = 1.01-1.11) and lowest O/E (1.16, 95% CI = 1.10-1.23) hospitals.ConclusionsCalculation of hospital-specific O/E for NCCN treatment guideline adherence, combined with minimum case volume criterion, as a measure of ovarian cancer quality of care is feasible and is an independent predictor of survival.