Recovery of physical function in lung transplant recipients with sarcopenia

Abstract

Background: Lung transplant (LTX) can provide a survival benefit and improve physical function for selected patients with advanced pulmonary disease. Sarcopenia is a systemic muscle-failure that can be found in a variety of life stages and disabilities. In this study, we follow the evolution of each variable defined in sarcopenia and the outcomes in LTX recipients with post-transplant sarcopenia.

Methods: Patients who underwent LTX at Tohoku University Hospital between 2013 and 2018 were consecutively included in the retrospective cohort study, with follow-up to 2019. Sarcopenia was defined by low muscle mass (the cross-sectional area (CSA) of erector spinae muscle (ESM) in thoracic CT with a threshold < 17.24 cm²/m²) and either low muscle strength (hand-grip with a threshold of < 26 kg in males and of < 18 kg in females) or physical performance (6-min walk distance with a threshold < 46.5% of predicted distance).

Results: Fifty-five recipients were included into the study, of whom 19 patients were defined as sarcopenic and 36 as non-sarcopenic. The muscle mass improved after transplant in both sarcopenic and non-sarcopenic individuals: the median ESM-CSA enlarged from 17.25 cm²/m² in 2 months post-LTX to 18.55 cm²/m² in 12 months (p < 0.001) and 17.63 cm²/m² in 36 months (p < 0.001) in non-sarcopenic individuals, while in sarcopenic patients it improved from 13.36 cm²/m² in 2 months to 16.31 cm²/m² in 12 months (p < 0.005) and 18.01 cm²/m² in 36 months (p < 0.001). The muscle mass in sarcopenia substantially recovered to close to non-sarcopenic conditions within 36-months (p < 0.001 in 2 months and p = 0.951 in 36 months). Accordingly, muscle strength and physical performance in both groups improved over time. No difference in survival was seen in both groups (Log-rank p = 0.096), and sarcopenia was not associated with an overall hazard of death (p = 0.147). There was no difference in the cumulative incidence of chronic lung allograft dysfunction between patients with or without sarcopenia (Log-rank p = 0.529).

Conclusions: Even patients with post-transplant sarcopenia have a chance to recover physical function to levels close to those without sarcopenia several years post LTX.

Keywords: Erector spine muscle (ESM); Hand-grip; Lung transplant; Muscle; Sarcopenia; Six-min walk distance (6MWD).

Fig. 1

The measurement of the cross-sectional area (CSA) of erector spinae muscle (ESM) in thoracic CT. (a) The image in thoracic CT at the lower margin of the 12th thoracic vertebra was viewed with WeVIEW Z-edition (Hitachi, Ltd, Tokyo, Japan). (b) The border of ESM-CSA was outlined (shown in yellow lines), and the area was automatically calculated

Fig. 2

Study flow

Fig. 3

Trend of variables after lung transplant in patients with and without sarcopenia. a The trend in the cross-sectional area of erector spinae muscle normalized to body surface area (cm²/m²), b % predicted hand-grip (HG) strength, c % predicted 6-min walk distance (6MWD), d body-mass index (BMI)(kg/m2) and e forced expiratory volume in the first second (FEV1)(L) were shown by months after transplant. The change at each annual assessment was compared to the first full assessment normally done in 2- or 3- months after transplant. Sarcopenia was shown in red solid line (n = 19) and non-sarcopenia in blue dashed line (n = 36). The difference between sarcopenia and non-sarcopenia was calculated with Mann–Whitney U test (MWU), described below the line graph. NS, not significantly different, *p < 0.05, **p < 0.01, ***p < 0.005 and ****p < 0.001

Fig. 4

Kaplan–Meier analysis in lung transplant recipients with and without sarcopenia. a Survival and b the cumulative incidence of chronic lung allograft dysfunction (CLAD) were shown by months after transplant. Sarcopenia was shown in red solid line (n = 19) and non-sarcopenia in blue dashed line (n = 36). The number of patients at risk is documented according to time