Comparative burden of arthropathy in mild haemophilia: a register-based study in Sweden

Introduction: Mild haemophilia is a congenital bleeding disorder affecting males. The burden of arthropathy in mild haemophilia has not been comprehensively described. Aim: The aim of this study was to compare the incidence, age at diagnosis and surgery for arthropathy and related hospitalizations between people with mild haemophilia and the general population in Sweden. Methods: This was a register-based cohort study. Eligible participants were those with mild haemophilia born between 1941 and 2008 and a randomly selected, birthdate and sex-matched comparison group from the general population. Follow-up was from birth (or earliest 1984) until death, emigration or end of the study in 2008. Data on arthropathy were obtained from a national patient register. Negative binomial and competing risk regression and Kaplan-Meier estimate curves were used in the analysis. Results: Overall, 315 people with haemophilia and 1529 people in the comparison group were included. Participants with haemophilia born between 1984 and 2008 had a ninefold (95% CI: 3.3-27.2) and 16-fold (95% CI: 6.7-36.5) increased incidence of arthropathy-related hospital admission and arthropathy diagnosis respectively. None in this cohort underwent surgery. Among participants with haemophilia born prior to 1984, the rates of arthropathy diagnosis and surgery of the index joints (knee, elbow, ankle) were increased twofold (95% CI: 1.0-3.2) and fivefold (95% CI: 1.7-17.8) respectively. Conclusion: Our data suggested a higher burden of arthropathy among individuals with mild haemophilia compared to the general population. Further research should investigate the need for targeted joint screening programmes among individuals with mild haemophilia.