Bone health in symptomatic carriers of haemophilia A: a protocol for a multicentre prospective matched-cohort study

INTRODUCTION: Haemophilia A is an X linked inherited bleeding disorder, caused by a decrease in coagulation factor VIII. Persons with haemophilia experience repeated musculoskeletal bleeding, which can lead to decreased range of motion, irreversible joint damage, low bone mineral density (BMD), and are at greater risk for osteoporosis. Women heterozygous for this mutation, also known as haemophilia A carriers, can have bleeding symptoms and even experience joint bleeding evidenced by radiological soft tissue and osteochondral changes. The prevalence of low BMD as a risk factor for osteoporosis has never been evaluated in carriers of haemophilia, and given the recent findings which suggest subclinical musculoskeletal bleeding in carrier women, we hypothesise that they too are at risk of impaired bone health. METHODS AND ANALYSIS: This is a national multicentre prospective matched-cohort study to compare BMD T-scores among symptomatic haemophilia A carriers, 50 years of age or older, with age-matched and body mass index-matched non-carriers (1:1). A total of 40 symptomatic carriers and 40 matched non-carriers will be recruited from St. Michael’s Hospital, Kingston General Hospital in Ontario, Canada and Foothills Medical Centre in Alberta, Canada. Multivariable linear regression models will be used to estimate the effect of haemophilia carriership on BMD T-scores, adjusting for age, body mass index and other relevant covariates. ETHICS AND DISSEMINATION: The protocol was designed and will be conducted in compliance with applicable laws, rules and regulations. Research ethics approval was obtained from St. Michael’s Hospital, Foothills Medical Centre, and Kingston General Hospital. Findings will be presented at international venues such as the American Society of Haematology and the World Federation of Haemophilia World Congress. The authors of this study will seek publication in journals such as Blood, Journal of Thrombosis and Haemostasis, American Journal of Hematology and British Journal of Haematology.