Low-molecular-weight heparin thromboprophylaxis in medical-surgical critically ill patients: a systematic review.

PURPOSE The study aimed to systematically review the effect of low-molecular-weight heparin (LMWH) thromboprophylaxis in medical-surgical critically ill patients in the intensive care unit. METHODS In duplicate and independently, we searched for relevant articles using MEDLINE and EMBASE; we also contacted experts and reviewed reference lists. For included studies, we abstracted data on study and patient characteristics, LMWH use, clinical outcomes (venous thromboembolism [VTE], bleeding, and mortality), laboratory outcomes (anti-Xa levels and thrombocytopenia), and methodological quality. RESULTS We included 8 prospective cohort studies and 1 randomized trial, with a total of 629 patients. Eight studies (n = 406 patients) reported anti-Xa levels and only 3 studies (n = 240 patients) reported on at least one clinical outcome. Low-molecular-weight heparin does not appear to bioaccumulate based on repeated measurements of trough anti-Xa levels. Thrombocytopenia occurred in 9.3% of patients receiving LMWH; heparin-induced thrombocytopenia was not reported. In studies reporting clinical outcomes, the frequency of VTE in patients receiving LMWH ranged from 5.1% to 15.5%, bleeding complications ranged from 7.2% to 23.1%, and mortality ranged from 1.4% to 7.4%. CONCLUSIONS Low-molecular-weight heparin may be effective for thromboprophylaxis in medical-surgical critically ill patients, but no trials have compared LMWH against an alternative active strategy; thus, LMWH cannot be recommended routinely. Trials testing LMWH thromboprophylaxis are required, which examine patient-important end points such as the incidence and clinical consequences of VTE, bleeding, heparin-induced thrombocytopenia, and mortality.