ABSTRACT
Severe COVID-19 has high mortality because cytokin storm will causes Neutrophil Extracellular Trap (NET) and thrombocyte activation. NET could damage alveolar tissue. Biomarker of NET is Citrullinated Histon H3 (Cit-H3). Thrombocyte activation can be depicted by thrombocyte index which are: trombocyte count, MPV, PDW, PCT and P-LCR. This research will analyze correlation cit-H3 and thrombocyte index with PaO2/FiO2 ratio and as mortality predictor in COVID-19 patient. This research is cross sectional in RSUD Dr. Soetomo from June 2020 - June 2021. Subject was adult patient confirmed PCR COVID-19. Blood sampling obtained first and third day of hospitalization. Measurement of Cit-H3 with competitive ELISA. Thrombocyte index on admission and PaO2/FiO2 ratio on admission and third day obtained from medical record. ROC analyses were done for cutoff point of thrombocyte index and CitH3 as mortality predictor. 37 subjects consisted of 19 death patient and 18 survive. Spearman correlation between PDW and PaO2/FiO2 on admission is significant with rs= -0.292 (p<0.05). Correlation CitH3 with PaO2/FiO2 is not significant. P-LCR is significantly higher in death group with cutoff >27% (AUC 0.697;sensitivity 78.9%;specificity 55.6%). Cit-H3 serum significantly higher in death group on admission day and third day. Cit-H3 increases significantly on third day in death group. Cutoff Ci-tH3 as predictor mortality on admission day:10.65 ng/mL (AUC 0.703;sensitivity 84.2%;specificity 55.6%);third day: 12.45 ng/mL (AUC 0.716;sensitivity 89.5%;spesificity 50%). Significant negative correlation between PDW and PaO2/FiO2. P-LCR, Cit-H3 could be used as mortality predictor in COVID-19.