Frailty as a predictor of mortality in lung cancer survivors: evidence from a nationally representative cohort NHIS 1997–2018

Frailty is a syndrome characterized by decreased physiological reserve and increased vulnerability to adverse health outcomes. Its impact on lung cancer survivors remains inadequately explored. This study examined the association between frailty and all-cause mortality in a nationally representative cohort. We analyzed data from the National Health Interview Survey (NHIS) (1997-2018) linked to the National Death Index through 2019. Frailty was assessed using a modified FRAIL scale, categorizing participants as robust, pre-frail, or frail. Cox proportional hazards models were used to evaluate the association between frailty and all-cause mortality, adjusting for demographic, socioeconomic, and health-related factors. Among 1,778 lung cancer survivors, 63.7% were robust, 13.1% were pre-frail, and 23.2% were frail. Frailty prevalence was significantly higher in lung cancer survivors than in cancer-free participants (P < 0.001). Kaplan-Meier analysis demonstrated significantly reduced survival probability with increasing frailty (log-rank P < 0.001). In fully adjusted Cox models, frailty was associated with a 2.12-fold increased risk of mortality (95% CI, 1.68-2.50, P < 0.001), and pre-frailty was also associated with increased risk (HR = 1.55; 95% CI, 1.27-1.90, P < 0.001). The impact of frailty on mortality was more pronounced in younger survivors and men. Frailty is a significant predictor of all-cause mortality in lung cancer survivors. Routine frailty assessments and targeted interventions may help improve long-term outcomes in this population.