Fig. 2

The association between baseline HE4 and the length of hospital stay (A) as well as the outcome of COVID-19 (B–D). There was no significant difference in HE4 in relation to shorter or longer hospitalization within the critically ill cohort, while those severe patients who had lower baseline HE4 level stayed for less days at hospital (A). A significant difference was observed in serum HE4 between survivors (n = 41) and non-survivors (n = 39) (B). When the alteration in HE4 level was studied during the follow-up regarding the outcome of these COVID-19 cases (n = 30), only a modest, non-significant change in HE4 was seen in those who died of COVID-19 eventually (C), while a significant decrease in HE4 between the baseline and follow-up sample was detected in those who recovered after treatment (D). Dots represent single results, while bars indicate median value. In parts C and D, lines connect HE4 values measured in baseline and follow-up samples. To compare the data of two groups, Mann-Whitney U test was applied, while HE4 values in baseline and follow-up samples were analyzed with each other by Wilcoxon matched-pairs signed rank test