Rethinking the one-size-fits-most approach to venous thromboembolism prophylaxis after radical cystectomy.

OBJECTIVES:Empirically dosed enoxaparin is routinely given in the postoperative period for venous thromboembolism (VTE) prophylaxis after radical cystectomy (RC). Patient-specific factors may alter its pharmacokinetics, and it is unclear whether this leads to levels sufficient for antithrombosis. We sought to evaluate variability of anti-factor Xa levels in a cohort of RC patients receiving perioperative enoxaparin prophylaxis. MATERIAL AND METHODS:Patients undergoing RC at a single institution were placed on a postoperative pathway that included enoxaparin. An anti-factor Xa level was drawn 2 to 4 hours after the third dose. The target range for prophylaxis was 0.3 IU/ml to 0.5 IU/ml. RESULTS:The primary outcome was anti-factor Xa level. Demographics, operative time, hospital course, and 30-days post-operative VTE were compared by anti-factor Xa level group using univariate and multivariable analyses. Between January 2018 and 2019, 107 RC patients remained on pathway and were included in our analysis. Sixty-five (61%) were below target range for VTE prophylaxis.  A single VTE event (0.9%) occurred in a subprophylactic individual. The subprophylactic group had a significantly higher body mass index (P < 0.01) than those within target range. CONCLUSIONS:Higher body mass index was associated with subprophylactic enoxaparin dosing after RC. Nearly two-thirds of patients had below target anti-factor Xa levels. This suggests that dosing could be further individualized, but given the low incidence of VTE, implications of dose-adjusted prophylaxis on VTE prevention remain unknown.