Association between fat‐free mass and survival in critically ill patients with COVID‐19: a prospective cohort study

Background

Most critically ill patients with COVID‐19 suffer from malnutrition and weight loss associated with negative clinical outcomes. Our primary aim was to assess body composition during acute and late phase of illness in these patients in relation to clinical outcome and secondary to tailored nutritional support.

Methods

Prospective cohort study including adult critically ill COVID‐19 patients. Body composition (fat‐free mass (FFM) (exposure of interest), fat mass (FM), skeletal muscle mass (SMM), phase angle (PA)) was determined with multifrequency bio‐electrical impedance analyses (BIA) in the acute and late phase. Nutritional support data were collected simultaneously. Clinical outcome was defined as ICU survival (primary outcome) and 30‐90 days thereafter, duration of mechanical ventilation, length of ICU stay and hospital stay (LOS). Non‐parametric tests and regression analyses were performed.

Results

We included 70 patients (73% male, median age 60 years). Upon admission median BMI was 30kg/m²: 54% obese (BMI>30kg/m²). Median weight change during ICU stay was ‐3kg: +3kg FM and ‐6kg FFM (‐4kg SMM). Body composition changed significantly (p<0.001). Regarding clinical outcome, only low PA was associated with prolonged LOS (OR=0.83, 95% CI=0.72‐0.96, p=0.015). Patients with optimal protein intake (>80%) during acute phase maintained significantly more FFM (2.7kg,p=0.047) and SMI (0.5 kg/m2,p=0.049) in the late phase compared with patients who received <80%.

Conclusion

Fat‐free mass decreased significantly during acute and late phase of illness, but we observed no association with ICU survival. Only low PA was associated with prolonged LOS. Fat‐free mass wasting occurred likely due to disease severity and immobility.

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