Objectives Muscle strength decline is reported to predict mortality in many cancers. However, there is little knowledge of the relation between muscle strength decline and clinical outcomes of allogeneic haematopoietic stem cell transplantation (allo-HSCT). This study aimed to determine the impact of pre-transplant lower extremity muscle strength (LEMS) on post-transplant overall survival (OS) and non-relapse mortality (NRM).

Methods In this retrospective cohort study, 97 adult patients underwent allo-HSCT during 2012–2020. LEMS was defined as knee extension force divided by patient’s body weight. The patients were divided into low and high LEMS groups based on pre-transplant LEMS. OS was measured using the Kaplan-Meier method and the Cox proportional hazards model. The cumulative incidence of NRM was evaluated using the Fine and Gray method, with relapse considered as a competing risk event.

Results Probability of OS was significantly lower in the low LEMS groups (HR 2.48, 95% CI 1.20 to 5.12, p=0.014) than in the high LEMS group on multivariate analysis. Five-year OS was 25.8% and 66.4% in the low and high LEMS groups, respectively. Risk of NRM was significantly higher in the low LEMS group (HR 4.49, 95% CI 1.28 to 15.68, p=0.019) than in the high LEMS group. The cumulative incidence of NRM was 41.4% and 11.1% in the low and high LEMS groups, respectively.

Conclusions Pre-transplant LEMS was a significant factor in predicting OS and NRM.