Ferritin in the coronavirus disease 2019 (COVID‐19): A systematic review and meta‐analysis

OBJECTIVE: The coronavirus disease 2019 (COVID‐19) has rapidly developed into a pandemic. Increased levels of ferritin due to cytokine storm and secondary hemophagocytic lymphohistiocytosis were found in severe COVID‐19 patients. Therefore, the aim of this study was to determine the role of ferritin in COVID‐19. METHODS: Studies investigating ferritin in COVID‐19 were collected from PubMed, EMBASE, CNKI, SinoMed, and WANFANG. A meta‐analysis was performed to compare the ferritin level between different patient groups: non‐survivors versus survivors; more severe versus less severe; with comorbidity versus without comorbidity; ICU versus non‐ICU; with mechanical ventilation versus without mechanical ventilation. RESULTS: A total of 52 records involving 10 614 COVID‐19‐confirmed patients between December 25, 2019, and June 1, 2020, were included in this meta‐analysis, and 18 studies were included in the qualitative synthesis. The ferritin level was significantly increased in severe patients compared with the level in non‐severe patients [WMD 397.77 (95% CI 306.51‐489.02), P < .001]. Non‐survivors had a significantly higher ferritin level compared with the one in survivors [WMD 677.17 (95% CI 391.01‐963.33), P < .001]. Patients with one or more comorbidities including diabetes, thrombotic complication, and cancer had significantly higher levels of ferritin than those without (P < .01). Severe acute liver injury was significantly associated with high levels of ferritin, and its level was associated with intensive supportive care, including ICU transfer and mechanical ventilation. CONCLUSIONS: Ferritin was associated with poor prognosis and could predict the worsening of COVID‐19 patients.