A Case of Acquired Hemophilia A: Usefulness of Various Methods for Judging Mixing Test Results for Monitoring the Effect of Immunosuppressive Therapy.

Background: Measurement of FVIII inhibitor (FVIII INH) levels is important for determining the effect of immunosuppressive therapy on acquired hemophilia A (AHA). However, FVIII INH can only be measured at a limited number of laboratories, which means that there are delays in obtaining the results at many sites.

Methods: A series of mixing tests were carried out in a case of AHA, followed by comparison of various methods for judging the obtained results in association with a change of FVIII INH. The mixing test results were judged using the visual waveform pattern method and the index of circulating anticoagulant (ICA), as well as the difference between the APTT values of delayed-type and immediate-type waveforms (APTT D-I) as a numerical index.

Results: All examined judgment methods reflected the change in FVIII INH, but ICA and APTT D-I were particularly sensitive for capturing this.

Conclusions: Our results suggest that a series of mixing tests are useful for rapid monitoring of the effect of immunosuppressive therapy on AHA.