Drug-induced neutropenia in the Stockholm region 1973-75: frequency and causes.

The records of 133 patients, discharged with a diagnosis of "agranulocytosis" (i.e. blood neutrophil levels less than 1.0 x 109/1) during the years 1973-75 in the Stockholm county region, were reviewed. In 45 cases the neutropenia was probably caused by drugs other than cytostatics, giving an annual incidence of drug-induced neutropenia of 0.01%. The most common drugs were thenalidine, sulfonamides and thyreostatics. Only one of the 45 patients died during the neutropenic phase. It is concluded that the pattern of drugs causing neutropenia has changed in Sweden compared with studies from the latter half of the 1960's, and only about 40% of the cases have been reported to the authorities.