Is Frailty a Mortality Predictor in Subjects with Chronic Obstructive Pulmonary Disease?

Background: Chronic obstructive pulmonary disease (COPD) has been frequently associated with frailty. The association between frailty and mortality in patients with COPD has not yet been fully elucidated and it remains controversial whether frailty or airflow limitation is more important in predicting mortality.Methods: A total of 141 subjects with stable COPD completed pulmonary function tests and the Kihon Checklist at baseline between 2015 and 2022 and were followed for a maximum of 95 months. Using the Kihon Checklist Total score, we classified patients' frailty status as robust (0-3), pre-frail (4-7), and frail (8-25).Results: At baseline, there were 67 (47.5%) in the robust group, 36 (25.5%) pre-frail, and 38 (27.0%) frail. Death was confirmed in 29 (20.5%). Univariate Cox proportional hazards analyses revealed that all predictive relationships of frailty and airflow limitation with mortality were statistically significant, and the C-index was similar, ranging from 0.63 to 0.66. According to the Log rank test and the Cox regression model, there was a significant difference between the frail and robust groups, (p=0.004 and p=0.005, respectively). No significant differences were found in either comparison with the pre-frail group. When stratification of frailty and FEV1 as well as sex were included as explanatory variables, multivariate Cox regression analysis showed a significant difference between the robust and frail groups with respect to mortality when the robust group was used as the reference (p=0.024). The robust and pre-frail groups did not differ significantly (p=0.163).Conclusion: The mortality of frail COPD patients is higher than those classed as robust. Despite frailty being a substantial mortality predictor, it is uncertain whether or not it is a better predictor than FEV1.