Association between hospital volume and overall survival of patients with metastatic non-small cell lung cancer.

Abstract

9044 Background: Prior studies have shown superior surgical outcomes of stage I-III non-small cell lung cancer (NSCLC) in centers with higher patient volumes. However, there is a lack of such information in stage IV NSCLC. In this study, we aim to determine the association between the number of patients with stage IV NSCLC treated annually at a treatment facility (volume) and all-cause mortality (outcome). Methods: Using the National Cancer Database, we identified patients diagnosed with stage IV NSCLC between 2004 and 2013. We classified the facilities by quartiles (Q; mean patients with NSCLC treated per year): Q1: < 13.8; Q2: 13.8 to 23.6, Q3: 23.6 to 30.3, and Q4: > 30.3. We used sandwich variance estimators to account for clustering of patients within facilities and Cox regression to determine the volume-outcome relationship, adjusting for demographic (sex, age, race), socioeconomic (insurance type), receipt of chemotherapy, and comorbid (Charlson-Deyo score) factors and year of diagnosis. Results: There were 281,654 patients with stage IV NSCLC treated at 1,275 facilities. The median age at diagnosis was 66 years, and 55.7% were men. The median annual facility volume was 23.6 patients per year (range, 1.0 to 301.4). The distribution of patients according to facility volume was: Q1: 6.6%, Q2: 14.9%, Q3: 25.4%, and Q4: 53.1%. The unadjusted median overall survival by facility volume was: Q1: 4.4 months, Q2: 4.5 months, Q3: 4.7 months, and Q4: 5.3 months ( P< .001). Multivariable analysis showed that facility volume was independently associated with all-cause mortality. Compared with patients treated at Q4 facilities, patients treated at lower-quartile facilities had a small but significantly higher risk of death (Q3 hazard ratio [HR], 1.05 [95% CI, 1.03 to 1.07]; Q2 HR, 1.06 [95% CI, 1.03 to 1.09]; Q1 HR, 1.09 [95% CI, 1.06 to 1.13]). Conclusions: Patients who were treated for stage IV NSCLC at lower-volume facilities had a significantly higher risk of all-cause mortality compared with those who were treated at lower-volume facilities. [Table: see text]