Effect of continuous renal replacement therapy on all-cause mortality in COVID-19 patients undergoing invasive mechanical ventilation: a retrospective cohort study

Yi Yang; Jia Shi; Shuwang Ge; Shuiming Guo; Xue Xing; Yanan Wang; Anying Cheng; Qingquan Liu; Junhua Li; Yong Ning; Fan He; Gang Xu

Numeric data were presented as the means and standard deviation (SD) or medians (interquartile range [IQR]) and were analyzed using Student's t-test or the Mann-Whitney U test depending on the data distribution. Categorical variables were displayed as frequencies and percentages and were analyzed using the Chi-squared test. The Kaplan-Meier method was used to estimate survival, and the log-rank test was used to evaluate differences between the two groups. The Cox regression model was conducted to adjust for potential confounders, including age, sex, the baseline values, and the average values of all tests between the start of invasive mechanical ventilation and the endpoint. Univariate Cox proportional hazards regression analyses were performed for all-cause mortality, the significant variants in the univariate analysis and the variables which have clinical significance were selected for inclusion in a multivariate "backward" stepwise Cox regression analysis. SPSS 23.0 (IBM Corporation, Armonk, NY) statistical software was used for statistical analysis. GraphPad Prism 6 (GraphPad Software, USA) was used for statistical analysis and visualization. A P-value of 0.05 or less was considered significant.