Statistical analysis
Categorical variables were expressed as numbers and percentages and
compared using the Pearson Chi square test or Fisher’s exact test as
suitable. Continuous variables were expressed as mean ± standard
deviation if normally distributed otherwise as median
(1st and 3rd quartiles) and compared
using Student’s t-test or non-parametric Mann-Whitney test as needed.
Association between baseline characteristics and the occurrence of
clinical event was evaluated by univariate analysis. Variables with p
value ≤0.20 in the univariate analysis were introduced in the
multivariate analysis using a binary logistic regression model with
Wald’s step-by-step method. Statistical significance was set at a
two-tailed probability level of <0.05. All analyses were
performed using IBM SPSS Statistics for Windows version 23.0 (released
2015, IBM SPSS Statistics for Windows, IBM Corp., Armonk, NY, USA).