Statistical analysis

Microsoft Excel 2016 was used for data entry, and statistical analysis was performed using the SPSS version 25. Qualitative data were expressed as numbers and percentages, and the Chi-squared test was used to assess the relationship between variables. Quantitative data were expressed as mean and standard deviation (±SD). Data normality was assessed using the one-sample Kolmogorov–Smirnov test, where the Mann–Whitney test was used for non-parametric variables. Variables with significant univariate associations were used in multivariable analysis. Multivariable logistic regression analysis was performed using backward variable selection to adjust for confounding and selection bias for factors associated with increase mortality. Variables not selected by the automated procedure were added back into models individually to evaluate for residual confounding. P <0.05 was considered statistically significant.