OC 62.3 - Apixaban for venous thromboembolism treatment in obese patients with weight >120kg or BMI >40 kg m2

Background: The 2016 ISTH SSC guidelines recommended against DOAC use in patients with a BMI of >40kg m2 or weight >120kg and if used drug specific levels be measured. The 2021 ISTH update for treatment of VTE, suggest that standard doses of rivaroxaban & apixaban are options regardless of high BMI and weight. Fewer supportive data exist for apixaban than rivaroxaban.

Aims: To assess apixaban levels in patients > 120kg or BMI > 40kg/m2 and correlate these with VTE recurrence

Methods: Retrospective case series of patients prescribed apixaban for treatment of VTE with apixaban levels measured between 01/02/2016 and 30/12/20. All patients were followed up for 12 months to determine VTE recurrence.

Results: A total of 240 VTE patient requests and 424 apixaban levels, 242 peak / trough levels on 134 patients on apixaban 5mg BD and 139 levels on 2.5mg BD. Apixaban 5mg bd 36 patients weight >120kg and 39 patients BMI >40kgm2. Figure 1 peak and trough levels are in keeping with those reported in the apixaban SPC www.medicines.org.uk/emc/product/2878/smpc . No patients on a dose of 5mg BD and BMI >40kgm2 suffered a recurrence of VTE during either the initial treatment phase or for the duration of the follow up period. One patient weight 140 kg suffered a recurrent DVT on apixaban 5mg bd 14 days after peak and trough levels (138 ng/ml and 54 ng/). The patient was non-adherent to treatment with no dose of apixaban in the five days preceding recurrent DVT.

Conclusion(s): In line with ISTH 2016 recommendations apixaban levels were in keeping with those predicted with no evidence of clinical recurrence of VTE supporting the new ISTH 2021 recommendations for apixaban treatment of obese patients with VTE