Risk for Heparin-Induced Thrombocytopenia (HIT) with Either Low-Molecular-Weight Heparin (Lmwh) or Unfractionated Heparin (Ufh)

A Cochrane review[Abstract] 1 included 3 studies with a total of 1398 postoperative patients. Participants were submitted to general surgical procedures, minor and major, and the minimum mean age was 49 years. Pooled analysis showed a significant reduction in the risk of HIT with LMWH compared with UFH (risk ratio (RR) 0.23, 95% confidence interval (CI) 0.07 to 0.73); low-quality evidence. The number needed to treat for an additional beneficial outcome (NNTB) was 59. The risk of HIT was consistently reduced comparing participants undergoing major surgical procedures exposed to LMWH or UFH (RR 0.22, 95% CI 0.06 to 0.75); low-quality evidence. The occurrence of HIT complicated by venous thromboembolism was significantly lower in participants receiving LMWH compared with UFH (RR 0.22, 95% CI 0.06 to 0.84); low-quality evidence. The NNTB was 75. Arterial thrombosis occurred in only one participant who received UFH. There were no amputations or deaths documented. Although limited evidence is available, it appears that HIT induced by both types of heparins is common in people undergoing major surgical procedures (incidence greater than 1% and less than 10%).

Comment: The quality of evidence is downgraded by imprecise results (few outcome events).

The following decision support rules contain links to this evidence summary:

• Alert on heparin-induced thrombocytopenia http://www.ebmeds.org/ebmeds/ebmeds_home.asp?mode=scripts&submode=view&id=scr00551&country=UK

References

• Junqueira DR, Zorzela LM, Perini E. Unfractionated heparin versus low molecular weight heparins for avoiding heparin-induced thrombocytopenia in postoperative patients. Cochrane Database Syst Rev 2017;(4):CD007557. [PubMed]