Mediating Effect of Deteriorated Kidney Function in Comorbidity-related Excess Deaths in COVID-19: A Retrospective Cohort Study

Abstract

Background In-hospital death risks vary in COVID-19 patients with comorbidities. Kidney function decline is prevalent in this course. Methods To explore the exact role of deteriorated kidney function, we applied a retrospective cohort study including 1266 participants in Wuhan Tongren Hospital between January 27 and March 3, 2020. Demographic characteristics, preexisting comorbidities history, organ function data and outcomes were extracted. Deteriorated kidney function was identified as the decline percentage, assessed by an increase in peak serum creatinine from the baseline. Mediating effect was calculated by mediation analysis. Key Results 1266 hospitalized COVID-19 patients (60±15 years, 47.8% are male) were included, with an overall in-hospital death rate of 4.42% (56/1266). For critical cases, 77.02% had at least one preexisting comorbidity. Patients with comorbidities suffered higher in-hospital death and more severe decline of kidney function. Compared to patients with minor function decline (<10%), significant risk increase was found in those with more severe one (OR 3.57; 95%CI 1.70 to 7.52; P=.001 for moderate with 10-50% decline, and 37.45; 95%CI 18.71 to 74.55; P＜.001 for severe with>50%). More interestingly, the mediation analysis found deteriorated kidney function played as an important mediator between different comorbidities and COVID-19 patients’ in-hospital death, with the mediation effect of 11%, 12%, 16% and 32% respectively for hypertension, COPD, CVD and CKD.Conclusions Deteriorated kidney function is strongly associated with increase of in-hospital death in COVID-19 and partially mediates the facilitating effect of preexisting comorbidities on in-hospital death. Thus, dynamic monitoring kidney function, preventing the deterioration of kidney function might be helpful to improve survival in COVID-19 patients, especially those with preexisting comorbidities.