Statistical analysis
Continuous variables have been presented as means ± standard deviation
or median values [first quartile, third quartile], and categorical
variables have been expressed as proportions. For comparisons between
groups, ANOVA as well as Kruskal-Wallis tests were used for continuous
variables, while χ2 tests were used for comparisons of
categorical variables. Then, we performed the Kaplan–Meier (KM) method
and log-rank tests to determine survival differences between four
groups. The Cox proportional
hazards model was applied to calculate the hazard ratio (HR) and 95%
confidence interval (CI) for each group of the cohort. In the adjusted
full model, we regrouped the study population by combining all
individuals with normal PR intervals and calculating the median HR for
each group. We did 3 sensitivity analyses to assess the robustness of
our findings. Subgroup analyses were also performed in clinically
relevant subgroups and interactions were tested. Missing data on
covariates were accounted for using a multiple imputation approach. All
data analysis was performed by using R statistical software (R, version
4.2.1)