HAEMOPHILIA B DIAGNOSTIC DISCREPANCY: A SURVEY TO CONFIRM THE DIAGNOSIS OF HAEMOPHILIA B

OBJECTIVES: To determine the frequency of misdiagnosis among documented factor IX (FIX) deficient (hemophilia B) patients of Khyber Pakhtunkhwa (KP) province of Pakistan and to discern role of different diagnostic tests employed in this regard. METHODS: Patients were identified through registries at transfusion centers. Out of 83 FIX deficient patients registered at transfusion centers and hemophilia care centers of KP province, 32 patients could be contacted and only 30 patients consented to be enrolled into the study. A comprehensive questionnaire depicting demographic details, clinical history and physical examination was filled out for each enrolled patient. Their blood samples were posed to first and second line coagulation tests both manually and on two different automated coagulation analyzers. RESULTS: The registered FIX deficient patients’ pool was found to have a mean age of 17.39±9.8 years. Out of 30 enrolled patients, diagnosis was correct in 18 (60.0%) patients and wrong in 12 (40.0%) patients. The misdiagnosed cases were hemophilia-A (n=9; 30%) and hypo-fibrinogenemia (n=3; 10.0%). All cases diagnosed previously on the basis of factor assays (n=8, 100%) were found to be correct while those diagnosed previously with mixing studies, only 08/18 (44.44%) had FIX deficiency. Out of 4 cases diagnosed on circumstantial evidence of isolated prolonged APTT along with established FIX deficiency in another sibling or maternal cousin, 2 had FIX deficiency. CONCLUSION: A large fraction of patients documented as FIX deficient on the basis of mixing studies are misdiagnosed. In clinical practice factor assays are more valid in comparison to mixing studies.