2.5. Statistical Analysis

Descriptive statistics were utilized to examine the distribution of baseline characteristics. The absolute standardized difference (ASD) was used to assess the covariate differences between the two groups. An ASD value of <0.10 indicates balanced characteristics between the study groups. The incidence density and 95% confidence interval (CI) of study events were calculated using the normal approximation to the Poisson distribution [16]. The relative risk and 95% CI were calculated using Poisson regression. The cumulative probability of mortality was assessed using Kaplan–Meier (K–M) analysis, and the difference in K–M curves between the study groups was evaluated using a log-rank test. After testing the proportional hazards assumption, Cox proportional hazard analysis was conducted to estimate the hazard ratio (HR) for mortality. The follow-up time was divided into three periods (1–7, 8–14, and 15–180 days) to investigate the immediate, short-term, and long-term associations between TXA administration and the risk of mortality or thromboembolic events.

We performed a sensitivity analysis using the inverse probability of treatment-weighted hazard ratio (IPTW-HR). This approach enabled us to address the imbalance between the treatment groups and minimize the influence of potential confounding variables. By employing IPTW, our goal was to obtain more robust and reliable results in our analysis. All statistical analyses were conducted using SAS software version 9.4, and a significance level of p < 0.05 was considered statistically significant.