Changes in body composition of patients undergoing hemodialysis during the coronavirus disease 2019 pandemic: a retrospective longitudinal study.

Background: The spread of coronavirus disease 2019 (COVID-19) has dramatically altered the lifestyles of many people worldwide. Several studies reported that body weight of young adults increased during the COVID-19 pandemic; however, weight loss has been observed in the elderly population. Therefore, trends in body composition due to the COVID-19 pandemic may vary depending on the characteristics of the population. This study aimed to investigate the changes in body mass index (BMI), muscle mass, and fat mass before and during the COVID-19 pandemic among patients undergoing hemodialysis. Methods: In this retrospective longitudinal study, we enrolled 115 clinically stable outpatients (mean age: 65.7 ± 11.2 years, 62.6% men) who underwent hemodialysis thrice a week. Baseline data were collected between April 2019 and March 2020, before the declaration of the COVID-19 emergency by the Japanese government. The follow-up measurements were performed between July 2020 and March 2021 during the COVID-19 pandemic. Patient characteristics, laboratory data, and BMI measurements were collected from the medical records. Muscle mass and fat mass were measured using bioelectrical impedance analysis. Results: BMI and fat mass among the study participants were significantly higher during the COVID-19 pandemic than before the pandemic (p < 0.01), but no significant change in muscle mass was observed. A restricted cubic spline function showed that the increase in BMI appeared to correlate well with fat mass, but not with muscle mass. Conclusions: BMI and fat mass of patients on hemodialysis significantly increased due to preventive measures against the COVID-19 pandemic in Japan. These findings may provide useful information in making nutritional management decisions for patients undergoing hemodialysis during and after the COVID-19 pandemic.