Muscle Strength and Muscle Mass as Predictors of Hospital Length of Stay in Patients with Moderate to Severe COVID-19: A Prospective Observational Study

Gil, S.; Jacob Filho, W.; Shinjo, S. K.; Ferriolli, E.; Busse, A. L.; Avelino-Silva, T. J.; Longobardi, I.; Oliveira Junior, G. N. d.; Swinton, P.; Gualano, B.; Roschel, H.

Importance: Strength and muscle mass are predictors of relevant clinical outcomes in critically ill patients, but in hospitalized patients with COVID-19 remains to be determined. Objective: To investigate whether muscle strength or muscle mass are predictive of hospital length of stay (LOS) in patients with moderate to severe COVID-19. Design: Prospective observational study. Setting: Clinical Hospital of the School of Medicine of the University of Sao Paulo. Participants: One hundred ninety-six patients were evaluated. Ten patients did not test positive for SARS-CoV-2 during hospitalization and were excluded from the analyses. The sample comprised patients of both sexes (50% male) with a mean age (SD) of 59 (SD = 15) years, body mass index of 29.5 (SD = 6.9) kg/m2. The prevalence of current smoking patients was 24.7%, and more prevalent coexisting conditions were hypertension (67.7%), obesity (40.9%), and type 2 diabetes (36.0%). Mean (SD) LOS was 8.6 days (7.7); 17.0% of the patients required intensive care; 3.8% used invasive mechanical ventilation; and 6.6% died during the hospitalization period. Main outcome: The outcome was LOS, defined as time from hospital admission to medical discharge. Results: The crude Hazard Ratio (HR) for LOS was greatest for handgrip strength comparing the strongest vs. other patients (1.54 [95%CI: 1.12 to 2.12; p = 0.008]). Evidence of an association between increased handgrip strength and shorter hospital stay was also identified when handgrip strength was standardized according to the sex-specific mean and standard deviation (1.23 [95%CI: 1.06 to 1.19; p = 0.008]). The magnitude of these associations remained consistent and statistically significant after adjusting for other covariates. Mean LOS was shorter for the strongest patients (7.5 , SD = 6.1 days) vs. others (9.2, SD = 8.4 days). Evidence of associations were also present for vastus lateralis cross-sectional area. The crude HR identified shorter hospital stay for patients with greater sex-specific standardized values (1.17 [95%CI: 1.01 to 1.36; p = 0.037]); however, we found increased uncertainty in the estimate with the addition of other covariates (1.18 [95%CI: 0.97 to 1.43; p = 0.092]). Evidence was also obtained associating longer hospital stays for patients with the lowest values for vastus lateralis cross-sectional area (0.69 [95%CI: 0.50 to 0.95; p = 0.025). Mean LOS for the patients with the lowest muscle cross-sectional area was longer (10.8, SD = 8.8 days) vs. others (7.7, SD = 7.2 days). Conclusions and Relevance: Muscle strength and mass assessed upon hospital admission are predictors of LOS in patients with moderate to severe COVID-19, which stresses the value of muscle health in prognosis of this disease.