Association between frailty and frailty change with chronic lung disease: results from two prospective cohort studies

BACKGROUND: The relationship between frailty and frailty change with the risk of chronic lung disease (CLD) among middle-aged and older adults remains unclear. This study explored the associations of frailty and frailty change with CLD based on two prospective cohort studies. METHODS: The data were drawn from the Health and Retirement Study (HRS) and the China Health and Retirement Longitudinal Study (CHARLS). Frailty status was evaluated by the frailty index (FI) and categorized as robust, pre-frail, and frail. FI change was calculated as the difference between the two repeated measurements of FI, and divided into stable FI, gained FI, and decreased FI. Group-based trajectory modeling was adopted to identify the trajectory of FI. Logistic regression models were then performed to estimate the odds ratio (OR) and 95% confidence interval (95% CI) between frailty status, frailty trajectory, and frailty change with the risk of CLD. RESULTS: A total of 9,178 participants from CHARLS and 11,262 participants from HRS were included. In the full-adjustment model, frail participants had higher risks of CLD compared to robust participants (CHARLS: OR = 2.28, 95% CI = 1.71-3.04; HRS: OR = 2.21, 95% CI = 1.17-4.17). The significantly elevated risks of CLD were also observed in the participants with the high-FI trajectory (CHARLS: OR = 2.11, 95% CI = 1.37-3.26; HRS: OR = 2.15, 95% CI = 1.16-3.97). The participants with decreased FI were at lower risks of CLD in the HRS (OR = 0.58, 95% CI = 0.38-0.87). However, gained FI was related to higher risks of CLD in the CHARLS (OR = 1.38, 95% CI = 1.11-1.72). CONCLUSION: Frail individuals might be related with higher risks of CLD. Moreover, the progression of frailty increased the risk of CLD, while recovery of frailty decreased the risk of CLD. Appropriate interventions aimed at reversion of frailty status may be needed to prevent CLD in current clinical respiratory care.