The influence of comorbidity and the simplified comorbidity score on overall survival in non-small cell lung cancer - A prospective cohort study

Introduction: We addressed the uncertainty of comorbidity as a prognosticator by evaluating comorbidity and the Simplified Comorbidity Score (SCS) as predictors of overall survival in non-small cell lung cancer (NSCLC). Methods: A prospective study included patients in whom NSCLC was diagnosed at an Australian cancer hospital between 2012 and 2014. Patients were assessed for SCS at recruitment and followed up every 3 months until death. Results: The cohort included 633 patients; their median age was 67 years (range 28-93), 63% were male, and 86% were ever-smokers. The median SCS at enrolment was 8 (range 0-19); 20%had an SCS higher than 9, and 11%had an SCS of 0. An SCS higher than 9 was associated with male sex, age older than 75 years, an Eastern Cooperative Oncology Group performance status of 2 or higher, and fewer cancer treatments. The 1-year overall survival rate was 62% (95% confidence interval: 58-66). In multivariate analysis, the strongest associations with mortality were metastatic disease (hazard ratio [HR] = 2.8, p < 0.01), Eastern Cooperative Oncology Group performance status of 2 or higher (HR = 2.0, p < 0.01), male sex (HR = 1.6, p < 0.01), more than 10% weight loss at diagnosis (HR = 1.5, p < 0.01), and age older than 75 years (HR = 1.5, p = 0.01). An SCS higher than 9 was not associated with overall survival (HR = 1.0, p = 0.8), and the effect of continuous SCS (HR = 1.1, p < 0.01) was explained by smoking status. Conclusions: In this cohort of patients with NSCLC the SCS was not a clinically significant predictor of overall survival over and above basic patient and disease factors.