We retrieved a total of 1,739 studies from the three databases and five additional papers via hand-searching. After preliminary screening, we conducted full-text evaluations of 173 of the studies. Among them, 27 (n = 1,302 patients) contained information on anticoagulation and mortality rate (23 determined mortality at discharge time, while 4 papers adopted 30 days as the time point)(Table 1 and Fig.4). All articles were observational studies, including four case series, four case–control studies, and 19 cohort studies, while the countries of publication included France (n = 5 articles), South Korea (n = 8 articles), the United States (n = 3 articles), Germany (n = 3 articles), Japan (n = 2 articles), Australia (n = 1 article) Italy (n = 2 articles), Singapore (n = 1 article), China (n = 1 article), and Poland (n = 1 article). All selected articles were scored on the Newcastle–Ottawa Scale, with two articles receiving nine stars, eight articles receiving eight stars, eight articles receiving seven stars, four articles receiving six stars, and five articles receiving five stars. All included articles were published after 2009.
3.1 In-hospital mortality rate
The combined in-hospital mortality rate was 70% (95% CI: 65%–74%, I2 = 68.3%), while the in-hospital mortality rate of the low-anticoagulation-target group was 61% (95% CI: 49%–74%, I2 = 76.5%), the in-hospital mortality rate of the moderate-anticoagulation-target group was 67% (95% CI: 59%–75%, I2 = 71.3%), the in-hospital mortality rate of the high-anticoagulation-target group was 78% (95% CI: 72%–83%, I2 = 47%), and the in-hospital mortality rate in the APTT-target group was 68% (95% CI: 61%–75%, I2 = 0)(Fig. 1).
3.2 Bleeding
A total of 16 articles contained information on bleeding and thromboembolic events. The overall incidence of bleeding complications in patients was 27% (95% CI: 19%–35%, I2 = 84.1%), while the incidence of bleeding complications in the low-anticoagulation-target group was 26% (95% CI: 18%–35%, I2 = 0), the incidence of bleeding complications in the moderate-anticoagulation-target group was 24% (95% CI: 6%–43%, I2 = 93.7%), the incidence of bleeding complications in the high-anticoagulation-target group was 28% (95% CI: 21%–35%, I2 = 0), and the incidence of bleeding complications in the APTT-target group was 32% (95% CI: 14%–50%, I2 = 77.8%)(Fig. 2). Separately, the incidence of bleeding complications in the no-loading-dose group was 24% (95% CI: 16%–32%, I2 = 60.7%) and the incidence of bleeding complications in the loading dose group was 29% (95% CI: 16%–42%, I2 = 90%)(Supplemental Digital Content – Fig. 1).
3.3 Thromboembolic events
The incidence of complications in all patients with embolism was 8.7% (95% CI: 5.2%–13.4%, I2 = 71.4%), while the incidence of thromboembolic events in the low-anticoagulation-target group was 5.4% (95% CI: 0.6%–22.1%, I2 = 83.2%), the incidence of thromboembolic events in the moderate-anticoagulation-target group was 6.9% (95% CI: 1.9%–14.1%, I2 = 74.6%), the incidence of thromboembolic events in the high-anticoagulation-target group was 11.8% (95% CI: 4.3%–22.1%, I2 = 67.1%), and the incidence of thromboembolic events in the APTT-target group was 12.4% (95% CI: 3.7%–25.1%, I2 = 71.1)(Fig. 3). Also, the incidence of thromboembolic events in the no-loading-dose group was 8.2% (95% CI: 3.4%–14.8%, I2 = 67.1%), while that of thromboembolic events in the loading dose group was 9.3% (95% CI: 3.9%–16.3%, I2 = 77.1%)(Supplemental Digital Content – Fig. 2).