Comparing low-molecular-weight heparin dosing for treatment of venous thromboembolism in patients with obesity (RIETE registry)

Because of the absence of comparative evidence, current guidelines and product monographs diverge in the dosing of low-molecular-weight heparin (LMWH) for obese patients with venous thromboembolism (VTE). We used the RIETE registry to compare the primary composite outcomes (VTE recurrence, major bleeding, or death) in patients with VTE who weighed >100 kg during LMWH therapy with capped doses of LMWH (18 000 IU/d) vs uncapped doses (>18 000 IU/d). Multivariable logistic regression analysis was used to account for possible confounders. A total of 2846 patients who weighed >100 kg were included: 454 (16%) received capped doses of LMWH, and the remaining 2392 received uncapped doses. Mean (standard deviation) LMWH treatment duration was 14.8 (20.6) and 14.3 (32.3) days, respectively. Thirty-one patients (1.9%) had VTE recurrences, 38 (1.3%) had bleeding episodes, 65 (2.3%) died, and 122 (4.3%) had at least 1 of the composite outcomes. Unadjusted outcome rates revealed that capped dosing was associated with a decrease in the composite outcome (rate ratio, 0.22; 95% confidence interval [CI], 0.04-0.75). Multivariable analysis confirmed that patients who received capped doses had significantly lower rates of the composite outcome (odds ratio, 0.16; 95% CI, 0.04-0.68) while receiving LMWH. These retrospective observational data suggest that capped dosing of LMWH is an acceptable alternative to uncapped dosing based on body weight, given the significantly lower composite event rate of VTE recurrence, major bleeding, and all-cause death.