Adherence to quality indicators and survival in patients with breast cancer.

Background: International initiatives increasingly advocate physician adherence to clinical protocols that have been shown to improve outcomes, yet the process-outcome relationship for adhering to breast cancer care protocol is unknown.
Objective: This study explores whether 100% adherence to a set of quality indicators applied to individuals with breast cancer is associated with better survival.
Research Design and Subjects: Ten quality indicators (4 diagnosis-related and 6 treatment-related indicators) were used to measure the quality of care in 1378 breast cancer patients treated from 1995 to 2001. Adherence to each indicator was based on the number of procedures performed divided by the number of patients eligible for that procedure. The main analysis of adherence was dichotomous (ie, 100% adherence vs. <100% adherence).
Measures: The outcome measures studied were 5-year overall survival and progression-free survival, calculated using the Kaplan-Meier method. The Cox's proportional hazard regression model was used for univariate and multivariate analyses.
Results: Most patients received care that demonstrated good adherence to the quality indicators. Multivariate analysis revealed that 100% adherence to entire set of quality indicators was significantly associated with better overall survival [hazard ratio (HR): 0.46; 95% confidence interval (CI): 0.33-0.63] and progression-free survival (HR 0.51; 95% CI, 0.39-0.67). One hundred percent adherence to treatment indicators alone was also associated with statistically significant improvements in overall and progression-free survivals.
Conclusions: Our study strongly supports that 100% adherence to evidence supported quality-of-care indicators is associated with better survival rates for breast cancer patients and should be a priority for practitioners.