Weight-adjusted tinzaparin appears to safely and effectively prevent venous thromboembolism (VTE) and major bleeding after bariatric surgery, according to a study published in the Journal of Thrombosis and Haemostasis.

The study was conducted at St. Joseph’s Healthcare Hamilton in Canada, where researchers performed a retrospective review of records from a total of 1279 patients who received a standardized, weight-adjusted tinzaparin regimen for 10 days after bariatric surgery between July 2009 and December 2012. The primary safety outcomes were the frequency of VTE and major bleeding.

In-hospital data were collected for 1212 patients and 30-day follow-up data were collected for 819 patients. The analysis revealed that within 30 days, 4 patients (0.5%) developed symptomatic VTE, including 3 cases of pulmonary embolism (PE) and 1 instance of mesenteric vein thrombosis. For patients for whom in-hospital records were available, 3 (0.2%) had VTE; all of these were instances of PE that occurred 1 to 5 days after surgery.

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In patients who completed the 30-day follow up, 13 (1.6%) had major bleeding events, all of which occurred during the surgical hospital admission. For all patients who were followed only until hospital discharge, 22 (1.8%) experienced major bleeding events, all of which were at gastrointestinal or surgical sites. There were 24 (2.9%) and 22 (1.8%) instances of non-major bleeding events in the 30-day follow up patients and in-hospital patients, respectively.

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Trough anti-factor Xa levels were 0.40 IU/mL or lower in the 187 patients tested and were undetectable in 74.8% of patients, indicating that tinzaparin does not bioaccumulate.

The authors concluded that “extended prophylaxis beyond the in-hospital period appears to be safe and feasible,” and “validation of this weight-based approach in a prospective management study is warranted.”


1. Tseng EK, Kolesar E, Handa P, et al. Weight-adjusted tinzaparin for the prevention of venous thromboembolism after bariatric surgery. J Thromb Haemost. 2018;16(10):2008-2015.