Pre Transplant Quadriceps Strength is a Modifiable Predictor of Functional Outcomes Following Lung Transplantation
.R.Walsh, D.C.Chambers, S.T.Yerkovich, N.R.Morris, P.M.Hopkins
Purpose: Severely limited functional status with poor rehabilitation potential is considered an absolute contraindication to lung transplantation. However, defining a threshold of functional status or rehabilitation potential suitable for active listing is complex. Therefore, the study aim was to determine if candidates pre-transplant quadriceps strength along with demographics and respiratory function can predict six-minute walk distance (6MWD) at three months post-transplant.
Methods: This study used a prospective observational repeated measures design. All lung transplant recipients at a single institution between Dec 2006 and May 2018 were considered for inclusion. Candidates’ demographics (age, sex, lung condition) and transplant hospital admission length of stay were recorded.6MWD, and quadriceps strength corrected for body weight (QS%) were recorded pre- and three months post-transplant.
Results 278 lung transplant recipients (142 male; mean age 45.7 ± 14.2 years; FEV133.6 ± 18.6%; 92 cystic fibrosis, 83 chronic obstructive pulmonary disease (COPD), 39 idiopathic pulmonary fibrosis) were studied. Pre-transplant 6MWD was 380.5 ± 138.6m and QS% was 98.8 ± 26.4%. Three months post-transplant 6MWD was 503.3 ± 116.2m. In a multivariate linear regression analysis, increased QS% pre-transplant(β=0.81, p=0.001), younger age(β=-1.59, p=0.011), male recipients (β=29.24, p=0.011), and reduced length of stay post-transplant (β=-2.77, p=0.001) were identified as independent predictors of increased 6MWD. In addition, a diagnosis of COPD (β=-64.47, p=0.001) or idiopathic pulmonary fibrosis (β=-51.96, p=0.017) independently predicted reduced 6MWD at three months post-transplant.
Conclusion: Pre-transplant quadriceps strength, age, sex, and diagnosis are independent predictors of post-transplant six-minute walk distance. Of these identified measures, onlypre-transplant quadriceps strength is potentially modifiable. Quadriceps strength should be considered when assessing candidacy and should be a key outcome measure when assessing efficacy of interventions designed to improve post-transplant outcomes.