Cumulative prevalence of venous thromboembolic events in ITP patients who underwent splenectomy compared with those who did not. There is an increased rate of VTE in patients with ITP that underwent splenectomy vs those who did not; however, the absolute risk is low in both groups. We included population-based/administrative cohort studies (N = 5) and retrospective (N = 7) and prospective (N = 2) cohort studies that reported outcomes on at least 50 patients with ITP, with a median follow-up >3 months.^22,55,68-72  For the splenectomy patients in particular, we included only studies that reported late (>3 months) VTE events to minimize selection bias from studies focusing on postoperative portal and splenic vein thrombosis. Time is calculated from date of splenectomy in the splenectomy group and date of enrollment in cohort for the nonsplenectomy group. When only median follow-up was provided, means were approximated as described by Wan et al.⁷³  Some selection bias is possible because the patients that underwent splenectomy may have had more severe disease than the comparison group.