Variability of Findings in Drug-Induced Immune Haemolytic Anaemia: Experience over 20 Years in a Single Centre

BACKGROUND: Drug-induced immune haemolytic anaemia (DIHA) is difficult to diagnose, and its true incidence remains obscure. Here, we present cases of DIHA identified at our institute over the last two decades. METHODS: Serological tests were performed according to standard procedures. Detection of drug-dependent antibodies was performed in the presence and absence of the relevant drug and/or their ex vivo antigens. RESULTS: Over the last 20 years, 73 patients have been identified with DIHA in our institute, which was related to 15 different drugs. The most common single drugs identified were diclofenac (n = 23), piperacillin (n = 13), ceftriaxone (n = 12) and oxaliplatin (n = 10). As far as data were available, haemolysis was acute in all patients, and signs of intravascular haemolysis were present in 90% of the cases. Haemolysis resulted in death in 17 patients (23%). The remaining patients recovered, but haemolysis was complicated by transitory renal and/or liver failure or shock in 11 patients. Upon initial evaluation, the antibody screening test was positive in 36 cases. A positive direct antiglobulin test (DAT) at least with anti-C3d was found in 65 cases, with anti-IgG only in 6 cases, and with anti-IgA only in 1 case. CONCLUSION: DIHA is a rare but potentially life-threatening disorder that should be considered if a patient develops haemolysis under drug treatment. The main serological finding is a positive DAT, primarily with anti-C3d.