Myostatin and irisin levels in predicting the outcome of patients with systemic inflammation: A prospective observational study

Background : Systemic inflammatory response syndrome (SIRS) is associated with changes in muscle metabolism. Resulting muscle weakness is linked with adverse outcomes, e.g. prolonged mechanical ventilation, length of hospital stay and increased mortality. Skeletal muscles produce myokines, which may contribute to the development of muscle weakness. The aim of this study was to assess the potential utility of selected myokine levels in predicting the prognosis of patients with SIRS. Methods : This was a prospective observational study. Levels of myostatin and irisin, selected anthropometric, laboratory and muscle parameters (ultrasound measured thickness of quadriceps muscle US QMT, hand grip strength HGS, lean body mass LBM) were recorded within 48h from admission and at the day 10 of hospital stay. Control group consisted of healthy individuals. Results : A total of 54 participants (30 in the study group and 24 controls) were included in the study. Primary outcome (LoS=length of hospital stay) was not significantly different in probands with higher or lower myostatin or irisin levels (p = 0.59 and p = 0.659). Myostatin and irisin levels in control group were significantly lower than in study cohort (11.86 µg/L vs. 29.04 µg/mL, p = < 0.001 and 33.70 µg/L vs. 41.80 ug/L, p = 0.015). Irisin levels were higher in women than in men both in probands (p = 0.028) and controls (p = 0.001). There was a significant correlation between myostatin and CRP and NLR (p = 0.001; p = 0.021) and between irisin and BMI (p = 0.001). Both myostatin (p = 0.008) and irisin (p = 0.019) levels were associated with change of US QMT. QMT correlated with LBM (p = 0.002) and HGS (p = 0.002). Conclusions : There was no significant association of myokine levels with LoS. A significant correlation between baseline myokines levels and US QMT change was present which suggest their potential role in muscle metabolism in critically ill patients. US QMT may be a useful method to monitor muscle wasting.