Correlation of hypocalcemia with poor prognosis of COVID-19 based on cox regression model: an analysis of 2 651 patients

ABSTRACT

ObjectiveTo investigate whether hypocalcemia is associated with poor prognosis in COVID-19 patients. MethodsA retrospective analysis was performed on 2 651 COVID-19 patients admitted to Wuhan Huoshenshan Hospital from February 4, 2020 to April 11, 2020. They were divided into low and normal calcium groups according to their serum calcium level lower than 2.11 mmol/L or not. Their basic demographic characteristics, results of laboratory tests, treatment, complications and outcomes were analyzed and compared between the 2 groups. COX regression model was used to analyze whether low calcium is an independent risk factors for poor outcomes in COVID-19 patients. ResultsThe low calcium group had significantly higher ratios of mechanical ventilation, extracorporeal membrane oxygenation (ECMO) and ICU occupancy (P<0.05);obviously higher incidences of sepsis, shock, hypoproteinemia, respiratory failure, coagulation disorders, acute kidney injury, acute myocardial injury, acute respiratory distress syndrome (ARDS), and even mortality (P<0.05);and remarkably longer length of hospital stay (P<0.001) when compared with the normal calcium group. The blood calcium level of mild and common, severe, and critical COVID-19 patients was 2.17 (2.11, 2.24), 2.13 (2.04, 2.21), and 2.03 (1.89, 2.18) mmol/L, respectively, and significant differences were seen among the patients (P<0.05). The calcium level was in a decreasing trend with the severity of COVID-19 (P<0.05). The calcium level was statistically lower in the dead patients than those survival [1.97 (1.87, 2.03) vs 2.17 (2.09, 2.23), P<0.001]. Multivariate Cox regression analysis indicated that serum calcium concentration <2.11 mmol/L was an independent risk factor for poor prognosis of COVID-19 (HR=5.695, 95%CI2.363-13.725, P<0.001). ConclusionLow blood calcium level is an independent risk factor for poor prognosis in COVID-19 patients. Correction for hypocalcemia may be an important strategy to improve the prognosis of COVID-19 patients.