Heparin-induced skin lesions are fairly common among patients receiving heparin for treatment or prophylaxis, especially among women, and those who are overweight or who have taken the drug for more than 9 days, a new study has determined.
Prior research had suggested that many cases were caused by heparin-induced thrombocytopenia. The study by Dr. Marc Schindewolf and colleagues contradicts those data: A delayed-type hypersensitivity reaction caused the lesions in all 24 of the cases they observed (CMAJ 2009 Sept. 28 [doi:10.1503/cmaj.081729
Dr. Schindewolf of the Hospital of the Johann Wolfgang Goethe University in Frankfurt, Germany, and his coauthors also postulated that heparin-induced skin lesions are probably much more common than currently believed. Their observed incidence of 7.5% far exceeded their expected findings of 2%, which were based on prior clinical observations. “During the study we were surprised by the high number of patients with [lesions],” they wrote. “For most of the patients, the diagnosis was made because of our study. Therefore, it is tempting to speculate that many cases of heparin-induced skin lesions are undiagnosed.”
The study comprised 320 patients enrolled over a 12-month period, all of whom were taking some form of heparin as treatment or prophylaxis. The patients' mean age was 61 years; the median duration of heparin use was 9 days, but it ranged from 7 to 1,095 days. Most (60%) were taking enoxaparin; 31% were taking nadroparin. The remainder was taking other forms of heparin.
In all, 24 patients developed heparin-induced skin lesions. Most of the cases were small eczema-like plaques at the injection site. A few patients had generalized itchy erythematous plaques. In 23 patients, a delayed-type hypersensitivity response was the confirmed cause. One patient refused to consent to a punch biopsy or allergologic testing. Although all of these patients were screened for immune-mediated heparin-induced thrombocytopenia, it was detected in only one patient.
Compared with those who did not develop lesions, more of those who did were women (71% vs. 45%), had a higher body mass index (30 kg/m
The lesions should be viewed as a symptom requiring an investigation of some underlying etiology, they wrote: “We recommend obtaining a punch biopsy; comparing platelet counts before, during, and after therapy; and performing appropriate laboratory investigations to exclude heparin-induced thrombocytopenia.”
The authors reported having no financial conflicts with regard to the study.