In patients with venous thromboembolism (VTE), morbid obesity was associated with lower mortality risk compared with in patients with normal weight, according to study results published in CHEST. The findings were consistent in patients with and without cancer, even after adjustment for other possible confounders.

Although previous studies have shown that obesity is associated with an increased risk for VTE, the effect of morbid obesity on clinical outcomes during anticoagulant therapy in VTE is not clearly understood.

In the current study, the researchers used data from the Computerized Registry of Patients With Venous Thromboembolism (RIETE; ClinicalTrials.gov Identifier: NCT02832245), aiming to assess the outcomes of anticoagulant therapy in morbidly obese (body mass index, ≥40 kg/m2) vs normal-weight (body mass index, 18.5-24.9 kg/m2) patients with acute VTE.

Of 75,452 patients with VTE enrolled in RIETE from March 2001 to September 2018, 1642 (2.2%) had morbid obesity and 14,848 (20%) had normal weight. Active cancer was recorded in 245 patients (14.9%) with morbid obesity and in 4198 normal-weight patients (28.3%).

In patients with obesity, the duration of anticoagulant therapy was longer compared with that in patients with normal weight; this applied whether they had cancer (median duration, 185 vs 114 days, respectively; P <.001) or not (median duration, 203 vs 177 days, respectively; P <.001).

Compared with normal-weight patients, those with morbid obesity were less likely to receive low-molecular-weight heparin as an initial therapy and were more likely to receive unfractionated heparin. In addition, patients with obesity were more likely to switch to vitamin K antagonists for long-term therapy compared with patients with normal weight. The daily doses of low-molecular-weight heparin per body weight were lower among patients with morbid obesity.

Mortality rate was much lower among cancer patients with morbid obesity compared with those with normal weight (hazard ratio [HR], 0.34; 95% CI, 0.25-0.45), and rate of VTE recurrence was similar (HR, 0.62; 95% CI, 0.34-1.05). Moreover, major bleeding events were less common in the group of patients with cancer and morbid obesity compared with those with normal weight (HR, 0.54; 95% CI, 0.28-0.96).

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As for patients who did not have cancer, mortality rate was again lower in the group of patients with morbid obesity compared with those with normal weight (HR, 0.43; 95% CI, 0.32-0.58). Rates of VTE recurrence (HR, 0.79; 95% CI, 0.53-1.15) and major bleeding events (HR, 0.82; 95% CI, 0.57-1.15) were similar.

Multivariable analysis confirmed a lower risk for mortality in morbidly obese patients, whether they had cancer (HR, 0.68; 95% CI, 0.50-0.94) or not (HR, 0.67; 95% CI, 0.49-0.96), but there was no difference in VTE recurrences or major bleeding in patients with or without morbid obesity.

The researchers acknowledged several study limitations, including the observational design, collection of weight data at a single point, relatively short follow-up, and differences in duration of anticoagulation therapy.

“These findings support the existence of a survival advantage of morbid obesity in this setting,” concluded the researchers.

Disclosure: The RIETE registry has been supported by the pharmaceutical industry. Please see the original reference for a full list of disclosures.

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Reference

Giorgi-Pierfranceschi M, López Núñez JJ, Monreal M, et al. Morbid obesity and mortality in patients with venous thromboembolism: findings from real life clinical practice [published online January 29, 2020]. Chest. doi:10.1016/j.chest.2019.12.040