Muscle strength and mass help predict length of stay in hospital for COVID-19 patients, study suggests

According to researchers affiliated with the University of São Paulo, these indicators can orient preventive care for the most vulnerable and rehabilitation for survivors who suffer from long-term complications.

By Maria Fernanda Ziegler  |  Agência FAPESP – A study conducted by researchers at the University of São Paulo (USP) in Brazil evaluated 186 hospitalized patients with moderate to severe COVID-19 and found that those with more muscle strength and mass tended to stay in hospital for less time. The results, therefore, suggest that these indicators can help predict length of hospital stay for patients with the disease.

“Muscle strength and mass can be useful predictors for preventive work with patients who risk progressing to the severe form of the disease, as well as serving as indicators of a possible need for longer-term care in the case of survivors with post-COVID complications. Individuals who are more vulnerable owing to less muscle strength and mass can be made fitter to cope with hospitalization. The lower the muscle strength and mass, the greater the chances of having complications. This can be generalized for a number of conditions, and we’ve now shown it to be valid for COVID as well,” said Hamilton Roschel, last author of an article reporting the study and one of the coordinators of the Applied Physiology and Nutrition Research Group at the University of São Paulo’s School of Physical Education and Sports (EEFE-USP) and Medical School (FM-USP).

The study was supported by FAPESP. The article, which has not yet been peer-reviewed, is available on the preprint platform medRxiv.

In the study, the researchers assessed each patient’s muscle strength on admission to hospital, using a handgrip dynamometer. Grip correlates well with overall muscle strength in the literature. Muscle mass was assessed by ultrasound scan of the vastus lateralis cross-sectional area at the side of the thigh.

Old age and chronic conditions such as type 2 diabetes increase the risk of developing severe forms of COVID-19. Nevertheless, the authors note, apparently healthier, younger individuals may also require hospitalization and even die from the disease. “This suggests that as yet undiscovered clinical characteristics may be associated with COVID-19 prognosis. Muscle strength and mass parameters are potential candidates,” Roschel said.

Skeletal muscle constitutes about 40% of an average person’s total body mass and plays a key role in various physiological processes, such as immune response, blood sugar regulation, protein synthesis, and metabolic rate. Previous research had already shown muscle strength and mass to be predictors of length of hospital stay in general, and this was confirmed by these researchers for COVID-19 patients.

“However, we’re not suggesting these parameters should be used instead of the biochemical markers that are well-known predictors of COVID-19 outcomes, such as oxygen saturation and C-reactive protein, among others,” Roschel said. “Information on muscle strength and mass will be even more important to treat survivors, who may suffer complications.”

Rehabilitation of survivors

Recovery for patients who survive COVID-19 but have a wide variety of sequelae is one of the many problems caused by the pandemic. According to experts, widespread post-COVID syndrome is set to overburden health services and can be considered a “syndemic” – a cluster of related health problems that interact synergistically.

“Patients hospitalized for long periods seem to suffer the most damage,” Roschel said. “A long hospital stay is associated with a series of negative events, and solving this problem should be included in our overall approach to treating the disease. When the number of new daily cases falls to tolerable levels, the rehabilitation of survivors will be the most daunting problem we have to face.”

The group is conducting another study to investigate the extent to which muscle strength and mass can be affected by hospitalization. “We have patients who lose over 30 kg while they’re in hospital and can barely walk when they’re discharged. The study will try to see how much length of stay impairs the patient’s functionality. The findings will be very important to assist rehabilitation. There’s considerable demand already,” Roschel said.

The article “Muscle strength and muscle mass as predictors of hospital length of stay in patients with moderate to severe COVID-19: A prospective observational study” is at: www.medrxiv.org/content/10.1101/2021.03.30.21254578v1.