[The prognostic value of myoglobin difference in sepsis related chronic critical illness]

Objective: To investigate the predictive value of myoglobin (Mb) for the prognosis of sepsis related chronic critical illness (CCI). Methods: Retrospective study was conducted on septic patients with the length of ICU stay equal or greater than 14 days, and sepsis-related organ failure assessment (SOFA) score equal or greater than 2 on the 14th day in ICU in the First Department of Critical Care Medicine at the First Affiliated Hospital of Sun Yat-sen University from January 2017 to March 2020. Patients' clinical and laboratory data were collected on the 1st and 14th day in ICU. The survival on day 28 in ICU was recorded. According to the myoglobin levels on day 1 and day 14, all subjects were divided into myoglobin elevation group and decline group. Kaplan-Meier survival curve was used to compare the cumulative survival rate at day 28. Cox regression analysis was used to analyze the independent risk factors of mortality. Receiver operating characteristic (ROC) curve was used to analyze the prognostic value of myoglobin. Results: A total of 131 patients with sepsis related CCI were recruited, including 58 patients in the elevation group and 73 in the decline group. The Mb level in elevation group on day 1 was significantly lower than that in decline group [172.40(59.99, 430.53) μg/L vs. 413.60(184.40, 1 328.50) μg/L, Z=3.749, P=0.000], and the Mb level on day 14 was the opposite change in two groups [483.65(230.38, 1 471.75)μg/L in elevation group vs. 132.20(76.86, 274.35)μg/L in decline group, Z=5.595, P=0.000]. Kaplan-Meier survival curve analysis showed that the 28-day cumulative survival rate of the elevation group was significantly lower than that of decline group (χ²=7.051, P=0.008). Cox ratio regression analysis suggested that elevated myoglobin was an independent risk factor for 28-day mortality in septic patients with CCI (OR=2.534, 95%CI 1.212-5.295, P=0.013). ROC curve analysis suggested that the sensitivity of myoglobin elevation in predicting mortality related to CCI within 28 days was 64.5%, and the specificity was 32.0% with area under the curve(AUC) 0.661(95%CI 0.550-0.773,P=0.007) and Jorden Index was 0.325. Conclusion: Elevated myoglobin, an independent risk factor for mortality within 28 days in ICU, can predict the prognosis of sepsis related chronic critical illness.