[Drug-induced immune hemolytic anemia: a retrospective study of 10 cases]

Drug-induced immune haemolytic anemia occurs in one case per million and can be fatal. Our aim was to describe the main characteristics and the type of drug involved.Cases were retrospectively identified using spontaneous notifications collected by our pharmacovigilance centre and the results of immuno-hematological investigations performed by the laboratory of French blood establishment of Lyon between 2000 and 2012. Inclusion criteria were: an immune (positive direct antiglobulin test), hemolytic, anemia (haemoglobin100 g/L), with at least a plausible causal relationship with drug exposure according to the French method of imputability or the presence of drug-dependent antibodies, and exclusion of other causes of hemolysis.Ten cases (5 men and 5 women, median age 54.4 years) were identified. Causal drugs were ambroxol, beta-interferon, cefotetan, ceftriaxone, loratadine, oxacillin, oxaliplatine, piperacillin-tazobactam, pristinamycin, and quinine. The median time to onset of anemia after starting the culprit drug was 6 days (2 hours to 16 days). The median nadir of hemoglobin was 57.9 g/L (range: 34-78). The direct antiglobulin test was positive in 8 patients: IgG only (n=4), IgG and complement (n=3), and IgA (n=1). Drug-induced immune haemolytic anemia was considered as definite in 5 cases with positive drug-induced antibodies, probable in 4 cases negative for the detection of drug-induced antibodies but with plausible or likely causal relationship with drug exposure, and probable with an autoimmune mechanism in 1 case.The diagnosis of DIIHA is often difficult because of the similarities with autoimmune haemolytic anemia and the inconstant sensitivity of immunologic tests that sometimes required repetitive assessment.