Investigating the prognostic ability of health-related quality of life on survival: a prospective cohort study of adults with lung cancer.

BACKGROUND: Health-related quality of life (HRQOL) is an important predictor for overall survival (OS). To date, no studies compared associations between HRQOL assessed before and after a cancer diagnosis for OS. Our objectives were to (1) investigate associations between HRQOL changes and OS and (2) identify the best HRQOL assessment time point to predict OS.

METHODS: We used the Surveillance, Epidemiology and End Results linked with the Medicare Health Outcomes Survey data. Medicare Advantage beneficiaries with SEER-confirmed, incident lung cancer between 1998 and 2013 were included. We only included individuals who completed pre- and post-diagnosis assessments. HRQOL was captured using the Short-Form (SF-36) and Katz's Activities of Daily Living (ADL). Cox Proportional Hazards models examined associations between HRQOL and OS, adjusting for potential confounders. AICs compared model fit.

RESULTS: Five hundred thirty-five adults with mean age of 75 years at diagnosis were included. We observed 300 deaths. Poor HRQOL was associated with greater risk of death across HRQOL assessments. SF-36 before diagnosis, after diagnosis, and change over time had AHRs of 1.01-1.08, 1.10-1.20, and 1.06-1.12, respectively. Pre-diagnosis, post-diagnosis, and changes in ADLs had AHRs of 0.90-2.06, 1.72-2.56, and 1.66-2.21, respectively. Post-diagnosis HRQOL and HRQOL change models had the smallest AICs and largest AHRs, suggesting they were most associated with OS.

CONCLUSIONS: This is the first study to compare the prognostic ability of pre-diagnosis, post-diagnosis, and HRQOL changes for OS. The prognostic value of HRQOL at distinct points in the cancer continuum underscores the importance of routine HRQOL monitoring as part of patient-centered cancer care.