Association between frailty and the risk of all-cause and cause-specific mortality among cancer patients

Background: Cancer patients are vulnerable to frailty. While few studies have focused on its association with the mortality risk among cancer patients, the current study aims to reveal this association. Methods In this cohort study, 4723 cancer patients were enrolled from the National Health and Nutrition Examination Surveys (NHANES, 1999–2018). Frailty status was quantified using the 53-item frailty index. Death outcomes were linked to National Death Index Mortality data (as of December 31, 2019). Cox proportional hazard models were used to estimate HR (95% CI). Results The median (IQR) of the frailty score was 0.190 (0.132, 0.277). During the median follow-up of 6.7 years, 1775 all-cause deaths (including 581 cancer deaths and 385 cardiac deaths) were documented. Compared to the lowest tertile of frailty score, the adjusted HRs (95% CIs) for the highest tertile were 2.698 (2.224, 3.272) in all-cause mortality ( P trend < 0.001), 2.145 (1.547, 2.973) in cancer mortality ( P trend < 0.001), and 3.735 (2.231, 6.251) in cardiac mortality ( P trend < 0.001). Moreover, a positive dose-response association between frailty score and mortality risk was determined. Per-unit increment of frailty score (natural logarithm transformed) was found to increase all-cause mortality by 159% ( P  < 0.001), cancer mortality by 103% ( P  < 0.001), and cardiac mortality by 256% ( P  < 0.001). The consistent result was shown when stratifying by age, gender, race, body mass index, and type of cancer. Conclusion This study suggested that the frailty index was positively associated with all-cause mortality and cause-specific mortality (including cancer and cardiac) among cancer patients.