Analysis of the Implementation of Blood Tests Specified in the Package Insert After Prescription of Thiamazole

Objectives The antithyroid drug thiamazole has long been known to cause the serious adverse effect of agranulocytosis, and performing regular blood tests is listed among the warnings on the package insert. We conducted a retrospective survey of how often doctors conducted blood tests in accordance with the package insert when thiamazole was prescribed at our hospital. Methods The subjects were patients to whom thiamazole was newly prescribed at our hospital between April 2004 and March 2012. During the target period, thiamazole was newly prescribed to 438 patients. Results We found that blood tests after prescription of thiamazole as listed in the warning section on the package insert are not performed sufficiently. The rate at which white blood cell counts were obtained decreased over time. The rate at which differential leukocyte counts were obtained was approximately 80% of white blood cell counts at all observational time points. In contrast, the percentage of subjects whose white blood cell counts were measured increased according to a time-trend analysis. Conclusions This study revealed that blood tests after prescription of thiamazole as listed in the warning section on the package insert are not performed sufficiently at our hospital. The rate at which differential leukocyte counts were obtained was approximately 80% of white blood cell counts at all observational periods. Physician education should be more rigorously performed than presently done, and automatic generation of warnings that urge blood tests and patient education regarding the importance of blood tests is also important.