2.5. Statistical analysis
The primary outcome of the study was whether the presence of NOAF is a risk factor for mortality in COVID-19. Secondary outcomes were the risk factors associated with the development of NOAF. All categorical variables are expressed as numbers and percentages, and continuous variables were expressed as median and interquartile range (IQR). Categorical variables between groups were compared with chi-square or Fisher’s exact test, continuous variables were compared with Mann–Whitney U -test. The independent effect of NOAF on hospital mortality was assessed with multivariate logistic regression analysis. To build the model, a purposeful selection method was used to select a subset of covariates that were considered clinically important, adjusting for confounders and statistical significance. An adjusted odds ratio (OR) and a 95% confidence interval (CI) were reported for each independent factor. A two-tailed P -value of < 0.05 was considered statistically significant. Statistical analysis was performed using SPSS (Statistical Package for the Social Sciences Version 24, IBM Corp., Armonk, N.Y., USA)