Survival associated with chronic obstructive pulmonary disease among SEER-Medicare beneficiaries with non-small-cell lung cancer

Objective: We investigated the impact of preexisting COPD and its subtypes, chronic bronchitis and emphysema, on overall survival among Medicare enrollees diagnosed with non-small-cell lung cancer (NSCLC). Methods: Using SEER-Medicare data, we included patients >= 66 years of age diagnosed with NSCLC at any disease stage between 2006 and 2010 and continuously enrolled in Medicare Parts A and B in the 12 months prior to diagnosis. Preexisting COPD in patients with NSCLC were identified using ICD-9 codes. Kaplan-Meier method and log-rank tests were used to examine overall survival by COPD status and COPD subtype. Multivariable Cox proportional hazards models were fit to assess the risk of death after cancer diagnosis. Results: We identified 66,963 lung cancer patients. Of these, 22,497 (33.60%) had documented COPD before NSCLC diagnosis. For each stage of NSCLC, median survival was shorter in the COPD compared to the non-COPD group (Stage I: 692 days vs 1,130 days, P<0.0001; Stage II: 473 days vs 627 days, P<0.0001; Stage III: 224 days vs 229 days; P<0.0001; Stage IV: 106 days vs 112 days, P<0.0001). For COPD subtype, median survival for patients with preexisting chronic bronchitis was shorter compared to emphysema across all stages of NSCLC (Stage I: 672 days vs 811 days, P<0.0001; Stage II 582 days vs 445 days, P<0.0001; Stage III: 255 days vs 229 days, P<0.0001; Stage IV: 105 days vs 112 days, P<0.0001). In Cox proportional hazard model, COPD patients exhibited 11% increase in risk of death than non-COPD patients (HR: 1.11, 95% CI: 1.09-1.13). Conclusion: NSCLC patients with preexisting COPD had shorter survival with marked differences in early stages of lung cancer. Chronic bronchitis demonstrated a greater association with time to death than emphysema.