Delayed-type hypersensitivity to low molecular weight heparins and heparinoids: cross-reactivity does not depend on molecular weight. Commentary

Conflicts of interest: The authors are employees of Laboratorios Farmacéuticos Rovi, S.A., manufacturer of bemiparin. Sir, We have read with interest the recent article by Grims et al. in this Journal.1 In their study, nearly all tested substances in eight patients with enoxaparin‐induced delayed‐type hypersensitivity (DTH) caused local eczematous reactions in at least some patients, with the exception of fondaparinux. The authors concluded that cross‐reactivity does not depend on molecular weight, and that, in patients with DTH to enoxaparin, the low molecular weight heparin (LMWH) bemiparin is not a suitable alternative. We would like to discuss some of the comments and conclusions of the authors and to add available information on this matter not referenced in their article.1 LMWHs have a well‐known efficacy and safety profile, being drugs of first choice in the prophylaxis and treatment of venous thromboembolism. Heparin‐induced DTH is an infrequent adverse event and generally of a mild to moderate intensity. A recent report showed a 0·29% rate of skin reactions, mainly injection‐site urticaria, among more than 10 000 patients included in observational studies with bemiparin in standard clinical practice.2 None of these cases was serious. This incidence is in agreement with that reported in the literature for LMWH.