Statistical Analysis of Glanzmann’s Thrombasthenia in Japan

Kojiro Yasunaga, First Department of Internal Medicine, Kansai Medical University, 1-Fumizonocho, Moriguchi, Osaka 570 (Japan) Glanzmann’s thrombasthenia (GT) is a well-defined inherited disorder ofplatelet function [1-3]. GT has an au-tosomal recessive inheritance and is characterized by the absence of ADP-induced platelet aggregation. It is caused by a deficiency or abnormality of the membrane glycopro-tein (GP) Ilb/ΠIa complex, with bleeding occurring due to defective platelet haemostatic plug formation. We have carried out nationwide surveys of congenital platelet function disorders in Japan on four occasions (in 1976,1981, 1986 and 1991). There were 98 patients in 1976,160 in 1981,178 in 1986, and 192 in 1991. Bleeding symptoms appeared at around 3 years of age in 60% of GT patients in all four surveys. The most common symptoms were epistaxis (70.7% in 1976, 70.8% in 1981, 70.2% in 1986, and 70.4% in 1991) and pur-pura (63.9% in 1976, 62.4% in 1981, 62.7% in 1986 and 61.9% in 1991). These were followed in descending order by oral mucosal bleeding, genital bleeding, excessive bleeding after tooth extraction, haematemesis and me-laena, excessive bleeding following trauma, and haematu-ria. In all 4 surveys, laboratory studies showed that the platelet count was normal in these patients, while the bleeding time was prolonged and ADP-induced aggregation was absent or decreased by more than 90%. The most interesting results were the mortality rate and the age distribution. The mortality rate was 6.8% in 1976, being slightly higher than that for haemophilia and related disorders (4.4% of 3,193 patients in 1976). The reason for this difference may be the lack of an effective haemostatic drug for GT patients, while coagulant factor therapy can be utilized for haemophilia. The mortality rate of GT patients has slowly declined since that time, with the standardized mortality ratios for age and sex showing a similar pattern (table 1). Table 1. Changes of the mortality rate of GT patients Year Mortality rate Standardized mortality ratio