Low pectoralis muscle on CT linked to elevated in-hospital COVID-19 mortality

Key takeaways:

• Patients with COVID-19 who died had lower pectoralis muscle cross-sectional area on CT scans compared with surviving patients.
• This parameter predicted mortality independently of the 4C Mortality Score.

Among patients with COVID-19, a low pectoralis muscle cross-sectional area on chest CTs appeared associated with heightened in-hospital mortality by day 30, according to results published in CHEST.

“Low CT scan-derived pectoralis muscle, high visceral adipose tissue, and low muscle cross-sectional area at L1 are statistically significantly associated with higher 30-day in-hospital mortality in patients with COVID-19,” Sophie I. J. van Bakel, MD, of the NUTRIM School of Nutrition and Translational Research in Metabolism at Maastricht University Medical Center+, and colleagues wrote. “Additionally, CT scan-derived pectoralis muscle cross-sectional area remains associated with 30-day in-hospital mortality in patients with COVID-19 independent of the clinical 4C Mortality Score.”

In a retrospective cohort analysis conducted in two hospitals, van Bakel and colleagues assessed 578 patients (mean age, 67.7 years; 64.6% men) with COVID-19 during the first wave of the pandemic to determine if muscle and adipose tissue cross-sectional areas from chest CT scans taken at admission are linked to in-hospital mortality within 30 days, independent of the 4C Mortality Score.

Researchers looked at medical records to calculate each patient’s 4C Mortality Score based on acute clinical signs and comorbidities.

Of the total cohort, 107 patients (18.2%) died in the hospital by day 30, with a median time to death of 6 days.

Researchers found more comorbidities and poorer scores on all clinical and blood parameters of the 4C Mortality Score among those who died vs. those who survived.

Notably, researchers could only evaluate L1 visceral adipose tissue and L1 muscle cross-sectional areas on about half of the scans. On the other hand, pectoralis muscle cross-sectional area could be determined on 97.3% of the scans.

When put against patients who survived, researchers found a significantly reduced pectoralis muscle cross-sectional area in patients who died (median, 32.6 cm² vs. 35.4 cm²; P = .002).

The L1 muscle cross-sectional area from CT scans tended to be lower for patients who died vs. patients who lived but was not significant, according to researchers.

Those who died in the hospital also had a significantly higher visceral adipose tissue cross-sectional area on CT scans vs. those who survived (median, 151.1 cm² vs. 112.9 cm²; P = .013).

Researchers found a link between pectoralis muscle cross-sectional area and 30-day in-hospital mortality prior to accounting for the 4C Mortality Score (HR = 0.97; 95% CI, 0.95-0.99), and this link was still significant following adjustment for the score (HR = 0.98; 95% CI, 0.96-1).

L1 muscle and visceral adipose tissue cross-sectional areas were each significantly linked to 30-day in-hospital mortality before adjusting for the 4C Mortality Score but not after.

“A focus on ensuring that chest CT scans include the L1 level in the future will allow for more precise (retrospective) comparison of the prognostic value of pectoralis and L1 muscle cross-sectional area,” van Bakel and colleagues wrote.

Researchers also called for further analysis to see whether the addition of pectoralis muscle cross-sectional area can improve the predictive value of the 4C Mortality Score.