Can Platelet Mass Index Be Used as a Prognostic Marker in Children Diagnosed with Multisystem Inflammatory Syndrome Associated with Coronavirus?

Objective: We’ve aimed at evaluating whether the platelet mass index (PMI) can be a prognostic marker for children diagnosed with MIS-C. Material and Methods: 31 children diagnosed with MIS-C and treated at our university hospital between March 2020 and November 2021 were included. Demographic data, clinical findings and laboratory values at the time of hospitalization, admission to the intensive care unit and duration of hospitalization were evaluated retrospectively. PMI of each patient at the time of hospitalization was calculated and recorded. Results: There was a statistically significant negative correlation between PMI and ferritin (r= -0.635, moderate, p<0.001), CRP (r= -0.377, weak, p= 0.036), and procalcitonin (r= -0.481, weak, p=0.006) levels. There was a statistically significant positive relationship between PMI and leukocyte count (r=0.367, weak, p=0.042) and lymphocyte count (r=0.384, weak, p=0.033). Median PMI values of the patients requiring intensive care (1701.35 fl/nl) were lower, compared to the median PMI values of the patients not requiring intensive care (2523.94 fl/nl), however, statistical results could not be reached due to the low (4 of 31) number of patients requiring intensive care. Median PMI values of the patients whose ferritin level was >400 ng/ml (1415.2; 533.4 – 3600.5) were statistically lower compared to the median PMI values of the patients whose ferritin level was ≤400 ng/ml (2705.7; 1395.2 – 9167.6).Conclusion: The findings in our study demonstrate that low PMI levels identified in children with MIS-C at the time of diagnosis may be with more severe clinical courses