Prediction of Timely Decaying Efficiency of Factor VIII Replacement Therapy Using Activated Partial Thromboplastin Time (aPTT) Test in Hemophilia A Patients Undergoing Treatment at the National Hospital of Sri Lanka (NHSL)

Introduction: Hemophilia A is a genetic disorder caused by Factor VIII deficiency. Prophylactic Factor VIII replacement therapy aims to maintain baseline levels and prevent bleeding. This study aimed to investigate the relationship between Activated Partial Thromboplastin Time (aPTT) and the time since the latest Factor VIII treatment (T) to predict the duration of therapy efficiency. It also aimed to establish a cut-off value for aPTT as an indicator of Elevated Factor VIII Levels (EFL) due to therapy. Patients attending Hemophilia clinic at NHSL were selected for the study (n=61). The study was conducted over 06 months.

Methodology: The time from the latest Factor treatment to blood collection (T) was recorded, along with age, weight, and Factor VIII dose from patient records. aPTT was measured using the COATRON-M4 coagulation analyzer. EFL was calculated based on the dose taken. Bivariate correlation analysis was performed to establish associations between aPTT & T and aPTT & EFL. Kaplan-Meier survival analysis was used to determine the maximum recurrence days after the latest Factor VIII dose. Finally, Receiver Operating Characteristic (ROC) curve analysis was conducted to establish aPTT cut-off values as an indicator of EFL in the body.

Results: aPTT showed a significant strong positive correlation with T. The Kaplan–Meier survival analysis estimated the median survival time is about 5 days with the initial recurrence of about 2 days, complete recurrence of about 8 days. According to the ROC analysis, the cut-off value of aPTT is estimated as 38.8 s with the sensitivity of 95.2% and specificity of 37.2%.

Conclusion: The results indicated that aPTT could predict the maximum duration of Factor VIII therapy efficiency in Hemophilia A patients. Cut-off values for aPTT as an indicator of EFL, determined using ROC curves, were also obtained. However, these findings need validation with a larger patient sample.