Five-year survival following a non-small-cell lung cancer diagnosis among Veterans Health Administration patients with schizophrenia and bipolar disorder

Abstract

Objective

Veterans with schizophrenia or bipolar disorder (SZ/BP) experience excess mortality due to several reasons, including cancer. We evaluated whether disparities exist in stage of non-small-cell lung cancer (NSCLC) diagnosis and survival between Veterans Health Administration (VHA) patients with and without SZ/BP.

Method

This retrospective evaluation used VHA data to identify patients newly diagnosed with NSCLC from 2005 to 2014. Bivariate analyses compared NSCLC stage at diagnosis by SZ/BP status. Kaplan-Meier and adjusted Cox proportional hazards regression analyses examined differences in survival by SZ/BP status. Meaningful differences were assessed using statistical significance, p < .01, and effect sizes of least 0.2 less/greater than 1.

Results

The cohort included 64,269 VHA patients with newly diagnosed NSCLC. These included 1605 (2.5 %) patients with schizophrenia and 1099 (1.7 %) with bipolar disorder. Stage at diagnosis did not meaningfully differ between patients with and without SZ/BP. After adjusting for stage of diagnosis and other factors, schizophrenia, but not bipolar disorder, was associated with an increased risk of five-year all-cause mortality compared to no SZ/BP (schizophrenia: HR 1.22, 95 % CI 1.14–1.30; bipolar: HR 1.01, 95 % CI 0.94–1.10).

Conclusions

VHA patients diagnosed with NSCLC who had schizophrenia experienced greater mortality compared to those without SZ/BP, despite no meaningful differences between the two groups in stage of NSCLC at diagnosis. Further work to understand drivers of this difference (e.g., access to NSCLC treatment) and subsequent interventions are needed.