Extended thromboprophylaxis post gynaecological cancer surgery; the effect of weight adjusted and fixed dose LMWH (Tinzaparin).

OBJECTIVE:Gynaecological cancer surgery is associated with high rates of venous thromboembolism (VTE) despite recommended prophylaxis. We sought to investigate the impact of extended prophylaxis with fixed dose and weight based LMWH in patients undergoing gynaecological cancer surgery. METHODS:VTE rates were recorded in patients who received LMWH prophylaxis (4500 IU Tinzaparin once daily) for the duration of hospital stay (2006-2012) (n = 610) and were compared with VTE rates in patients who underwent surgery after the introduction of extended prophylaxis (3500/4500 IU Tinzaparin for patients with BMI < 40kg/m2 and 75 IU/kg for BMI > 40 kg/m2) (2012-2017) (n = 651). Peak (4 h) anti-Xa levels in a subset of patients were also evaluated. RESULTS:73 (5.7%) cases of VTE were recorded during 1 year of follow-up. 20 cases occurred during hospital stay. There was no significant difference in the rate of VTE between the extended prophylaxis cohort and the standard prophylaxis cohort. 23/24 patients who developed VTE in the extended prophylaxis cohort received a fixed (4500 units) dose of Tinzaparin. 63% of patients who received a fixed LMWH dose had peak anti-Xa levels below the target range (0.2-0.4 IU/ml). Peak anti-Xa was lower in patients who subsequently developed VTE compared with those who received either fixed dose (P = 0.041) and weight adjusted Tinzaparin (P = 0.0006). CONCLUSIONS:Extended prophylaxis with Tinzaparin does not significantly reduce VTE rates in gynaecological cancer patients post surgery. Peak anti-Xa levels may be suboptimal in many patients receiving a fixed LMWH dose. Further studies are required to determine whether weight adjusted doses of Tinzaparin may provide more effective prophylaxis following gynaecological cancer surgery.