Cross-reactivity (CR) between heparins is frequent, therefore identification of therapeutic alternatives is essential. Our objetive was to analyze clinical and allergic characteristics of hypersensitivity to Low Molecular Weight Heparins (LMWH) and to determine safe alternatives.
We analyzed all patients suspected of LMWHs allergy, between 2012 and 2016 in our Unit. We evaluated clinical characteristics and Allergy study: patch tests (PTs), intradermal tests (IDTs), and subcutaneous challenge tests (SCTs) to the culprit LMWH, other LMWHs or Fondaparinux when skin test was negative.
30 patients were included, LMWHs allergy was confirmed in 17. of whom 88% were women, median age 62 years (range 32-81 years). 88.2% had delayed reactions. 82.4% were local reactions (erythema eczematous plaques in injection site). The onset of reactions varied between 1 and 15 days. Enoxaparin and Bemiparin were the most frequently implicated (59% and 29% respectively). PTs were positive for all LMWHs in 1 of the 5 patients tested. IDTs were performed in 16 patients, 32% positive of all tested heparins. SCTs with some LMWHs were done in 12 patients and we confirmed tolerance in 8 of them. 9 patients tolerated Fondaparinux if it was necessary. CR was found in 64.7% of patients. Heparins with the highest CR were: Bemiparin and Enoxaparin.
Enoxaparin was the most frequently involved due to its frequent use. High CR between heparins was observed. Different alternatives LMWHs from the implicated one were tolerated in several patients. Fondaparinux was a safe option in our study.