Inhibitor development in hemophillia A patients

SUMMARY In 58 hemophilia A patients aged 1-18 years (mean 9.5±4.7 years),the prevalance of inhibitor development was found 27% by Bethesda method during the time period between November 1995 and September 1997. Inhibitor activity was not detected in any of 14 mild hemophiliacs while it was present in 9 of 27 (33%) moderate and 7 of 17 (41%) severe cases. Development of inhibitors was significantly high (p=0.02) in moderately and severely affected patients when compared with mild cases. No significant difference was found between moderate and severe cases in this respect (p>0.05). Among moderate hemophiliacs, 7 had low titreş (0.50-2.0 BU) and 2 had high titreş (44-500 BU) of inhibitors, and among severe hemophiliacs, 5 had low titreş (0.50-1.8 BU) and 2 had high titreş (50-358 BU) of inhibitors. At follow-up of patients inhibitors were transient in 17% and the prevalance of inhibitor development was 1 0% at the end of the study. Development of inhibitors was not affected by the amount of time the patients had been receiving F VIII (p>0.05), while it was significantly associated with the patient's age (p=0.01), number of bleeding episodes within the last year (p=0.001), frequency of F VIII administration ( p= 0.001), number of F VIII treatment days (p=0.001), and F VIII level ^ 2% (p<0.05). Inhibitors did not develop in patients who received only fresh frozen plasma (p<0.05). Some of the patients who used F VIII concentrates had inhibitors. No significant difference in inhibitor development was found between the patients who used the most common products such as Koate HP or Nordiate and those who did not (p>0.05). The patients who had no inhibitors were exposed to F VIII median 24 days before, while those who had inhibitors were exposed to F VIII median 8 days before, and the difference was significant (p<0.05). Inhibitors were persistant in patients who had had longer bleeding episodes. Logistic regression analysis showed that patient's age (p=0.05), number of bleeding episodes within the last year (p=0.01), frequency (p=0.02), and number of days of F VIII administration (p=0.02) significantly affect inhibitor development, but the duration of F VIII treatment does not affect (p>0.05) inhibitor development. 45