Is Frailty Associated with Sarcopenia and Dynapenia in Lung Transplant Candidates?

Abstract

Physical frailty is a predictor of pre- and early post-transplant outcomes in lung transplant patients, and may be driven by the presence of sarcopenia (loss of muscle mass), dynapenia (decline in muscle contractile function) and/or mobility limitations. The purpose of this study was to examine the association between physical frailty (Fried Frailty Index; FFI) and measures of sarcopenia, dynapenia and mobility in lung transplant candidates. As a secondary aim, we examined the relationships between sarcopenia and dynapenia. 49 lung transplant candidates from the Frailty and Sarcopenia in Organ Transplantation (FROST) cohort study were included. Frailty was evaluated using the FFI. Dynapenia was assessed by quadriceps muscle strength and power using computerized dynamometry. Sarcopenia was evaluated using B-mode ultrasound to obtain quadriceps (rectus femoris) cross-sectional area (CSA) and muscle quality (echogenicity). Mobility was measured using the Short Physical Performance Battery (SPPB). Bivariate associations were examined using Spearman's rho. The sample included 24 patients with ILD, 18 with COPD, and 7 with other diagnoses (53% females; age 59.6±13yrs, FEV1 1.14±0.66L, BMI 25.3±4.0 kg/m2). Based on the FFI, 22% were frail, 71% were pre-frail, and 6% were not frail. There was an association between FFI and the SPPB score (r= -0.41, p=0.003); specifically, with the chair stands component of the SPPB (r=0.30, p=0.035). No significant correlations were found between FFI and sarcopenia or dynapenia measures. Quadriceps muscle strength and power were associated with muscle CSA (r=0.44 and 0.47, respectively; p< 0.002) and echogenicity (r= -0.38 and -0.58, respectively; p< 0.008). Mobility limitations appear to overlap with the frailty phenotype in lung transplant candidates, however the presence of sarcopenia and dynapenia may be distinct from frailty.