Key result
Subcutaneous skin testing yields ~83% positivity in suspected heparin allergy, with frequent cross-reactivity.
Why the study?
Does subcutaneous skin testing reveal cross-reactivity between LMWHs, UFHs, and danaparoid in patients with suspected delayed-type hypersensitivity to heparin?
Observational (n=18)
Does subcutaneous skin testing reveal cross-reactivity between LMWHs, UFHs, and danaparoid in patients with suspected delayed-type hypersensitivity to heparin?
Delayed-type hypersensitivity to heparins exhibits considerable cross-reactivity between LMWHs, UFHs, and danaparoid, suggesting that subcutaneous testing of a panel of anticoagulants is useful to identify safe treatment options.
Subcutaneous testing may identify safe options in suspected heparin allergy; leaves open need for prospective validation of cross-reactivity patterns.
BACKGROUND: Delayed-type hypersensitivity (DTH) reactions in patients receiving heparin may occur with both unfractionated (UFHs) and low molecular weight heparins (LMWHs). Skin testing is a clue to detect tolerated heparin or heparinoid preparations for further treatment. OBJECTIVE: To study in vivo cross-reactivity between LMWHs, UFHs, and danaparoid by skin testing in patients with suspected DTH to heparin. METHODS: Patients who fulfilled the criteria for the diagnosis of suspected heparin allergy were involved in a prospective study after informed consent. Patients presented with or had a history of typical erythematous plaques at the heparin injection sites. Skin testing was performed by subcutaneous injections of heparin (300-500 IU anti-Xa activity) and danaparoid (375 IU, eight patients). Desirudin (27,000 IU) was tested in three patients. We read skin reactions after 24, 48, and 96 hours and after 7 days. RESULTS: Fourteen female and 4 male patients were included in our series. Erythematous plaques had been reported or developed after 14-35 days in patients during first-time heparin treatment and after 2-10 days in reexposed patients. Positive skin test results were seen in 15 of 18 (83.3%) patients. Of these, 11 (73.3%) showed cross-reactivity between heparins and/or danaparoid. Six patients reacted to LMWHs only, nine patients to both LMWHs and UFHs. Danaparoid was tolerated in six of eight patients; desirudin was tolerated in all three patients tested. CONCLUSIONS: DTH to heparins is characterized by considerable cross-reactivity between LMWHs, UFHs, and danaparoid. UFHs may be tolerated even if LMWHs are not. Subcutaneous testing of a panel of heparins, danaparoid, and desirudin (hirudin) is recommended to determine acceptable treatment options for patients allergic to specific heparins.
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Grassegger et al. (2001) conducted an observational in Suspected delayed-type hypersensitivity to heparin (n=18). Subcutaneous skin testing with heparins, danaparoid, and desirudin was evaluated on Positive skin test results. Subcutaneous skin testing in patients with suspected heparin allergy yielded positive results in 83.3%, with 73.3% of these showing cross-reactivity between heparins and/or danaparoid.
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