Determinants of Physical Activity Levels in Allogeneic Hematopoietic Stem Cell Transplantation Recipients

Respiratory and skeletal muscle strength and submaximal exercise capacity and physical activity levels are known to be reduced in a significant percentage of patients prior to hematopoietic stem cell transplantation (HSCT). However, determinants of physical activity levels of HSCT recipients have not been investigated so far. The aim of this study was to determine the role of physical activity levels in HSCT recipients. Patients and Methods: This prospective cross sectional study included 36 HSCT recipients. Physical activity levels were assessed using a multisensory armband device and pulmonary function tests. Functional exercise capacity was evaluated with 6-minute walking test (6MWT), respiratory muscle strength (MIP, MEP) with mouth pressure device, peripheral muscles strength with dynamometer, and dyspnea with Modified Medical Research Council (MMRC) dyspnea scale. Correlations of exercise capacity parameters were done with the grade of cardiac and pulmonary toxicity, febrile neutropenia, and transplant related mortality (TRM). Results: All HSCT recipients were inactive (<3.0 METs) according to daily average METs (1.26±0.18 METs) and 88.88 % were walking <7.500 steps/day. Daily average METS were inversely correlated with MMRC dyspnea scale (r 0,492, p= 0,007).  Adjusted DLCO values showed negative correlation with the grade of febrile neutropenia (r 0,612, p=0,007). The grade of cardiac toxicity showed negative correlation with adjusted DLCO values (p=0,006) and quadriceps femoris muscle strength (p= 0,046). Respiratory and quadriceps femoris muscle strength were positively correlated with the number of steps per day (p=0,011 and p=0,001 respectively). Performance status prior to HSCT showed negative correlation with TRM (p=0,05). In multiple regression analysis; 24 % of the variance in the daily average METs was explained by MMRC (p=0.07); 13 % of the variance in survival duration explained by quadriceps femoris strength (p=0.03); 54.6 % of the variance in cardiac toxicity was explained by DLCO and quadriceps femoris strength (p=0.024). Conclusions: Physical inactivity is a significant problem in HSCT recipients. Peripheral muscle strength and dyspnea are significant predictors of physical activity levels. Exercise interventions to improve cardiorespiratory fitness and muscle strength may lead to beneficial effects on transplant outcomes in terms of the grade of cardiorespiratory toxicities, febrile neutropenia and TRM.