Drug-related blood dyscrasias in a Swedish reporting system, 1985-1994.

Drug-related blood dyscrasias as reported in Sweden during a 10-yr period have been analysed in relation to sales and prescription data. The number of cases reported were as follows: agranulocytosis 390, thrombocytopenia 391, pancytopenia 50 and aplastic anaemia 36. The annual incidence rates per 10(6) inhabitants were: agranulocytosis 4.8, thrombocytopenia 5.6, pancytopenia 1.1 and aplastic anaemia 0.5. Incidences in the elderly were higher for all dyscrasias except aplastic anaemia. The most commonly reported drugs for all dyscrasias were sulphonamides and diuretics, but when related to sales data the risk of agranulocytosis was high for clozapine, dapsone, mianserin and sulphasalazine, while the risk did not seem to be increased for furosemide. For thrombocytopenia, furosemide, co-trimoxazole and the measles, mumps and rubella vaccine were most commonly reported. The risk for pancytopenia and aplastic anaemia was increased for acetazolamide and co-trimoxazole. As spontaneous reporting systems are primarily set up for signalling purposes, such data must always be interpreted with utmost care.