Survival disparity among non-small cell lung cancer patients: Can adherence to quality indicators reduce the socioeconomic differences?

Background: Concern has been raised over the disproportionate mortality among cancer patients with low socioeconomic status. However, physician adherence to evidence has been shown to improve outcomes. We sought to explore whether of 100% adherence to a set of quality indicators with non-small cell lung cancer is associated with better survival, even among socially vulnerable groups. Method: We carried out a retrospective cohort study in the national health insurance database, combined with cancer registry data and death registry. A set of quality indicators applied to individuals with non-small cell lung cancer were used to measure the quality of care in 24,091 lung cancer patients newly diagnosed from 2004 to 2007. The main analysis of adherence was dichotomous as 100% adherence or not. Data was analyzed using Cox proportional-hazards regression model, controlling for the characteristics of patients and the characteristics of healthcare providers. Result: Most patients (79.8%) received care with complete adherence to the quality indicators. Multivariate analysis revealed that 100% adherence was associated with better overall survival (HR: 0.54, CI: 0.52-0.56). Although patient with lower income or unemployment were at high risk of mortality, 100% adherence to quality indicators significantly moderate the relationship between socioeconomic factors and conditions of survival. Conclusion: Although socioeconomic differences of survival exist in non-small cell lung cancer, complete adherence to quality indicators may narrow the disparity.