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Bone mineral density in Canadian children with severe haemophilia A or B: a cross-sectional study

Abstract Background Previous research has shown that bone mineral density (BMD), a measure of bone strength, may be lower among people with haemophilia. However, the majority of this research has been done in adults and in countries where the treatment for haemophilia differs from the standard of care in Canada, and there is a lack of paediatric data. Aims The primary objective of this study was to determine whether Canadian children and youth with severe haemophilia A and B have BMD similar to healthy controls matched for height, age and weight (HAW-score). Secondary objectives included the exploration of any association between BMD and the following variables: factor replacement regimen, Hemophilia Joint Health Score (HJHS), bleeding history, physical activity level, and dietary intake of calcium, vitamin D, vitamin K and protein. Methods A cross-sectional observational study was designed to determine the BMD of children with severe haemophilia A and B in Canada. Ethical approvals were obtained from participating institutions. Thirty-eight participants aged 3–18 with severe haemophilia A and B were recruited from two treatment centres in Canada. Subjects underwent dual-energy X-ray absorptiometry (DXA) scan, and data was collected from regular clinic visit to identify factor replacement regimen, HJHS, and number of joint bleeds over the lifespan. Physical activity level and dietary intake of calcium, vitamin D, vitamin K and protein were identified using self-report questionnaires. Results Participants showed a mean spine BMD Z-score and HAW-score higher than controls, with no participants showing a spine Z-score or HAW-score of <0. Hip BMD score was within normal range, and 2 participants had a Z-score and HAW-score of <−2. Total body BMD score was lower than controls, with 6 participants having a Z-score of <−2.0, and 3 participants having a HAW-score of <−2.0. Factor replacement regimen, HJHS, calcium intake, and physical activity level had no relationship to BMD Z-score or HAW-score. Low intake of vitamin D was associated with a low hip and spine BMD Z-score and HAW-score. Participants with a HJHS joint score greater than 0 had a higher total body HAW-score than those who had a joint score of 0. Conclusion Canadian children with severe haemophilia A and B demonstrate differences in spine and total body BMD from height-, age-, and weight-matched controls, where spine BMD is higher than controls and total body BMD is lower than controls. Studies with a larger sample size are needed to clarify the status of BMD in children with haemophilia treated with primary prophylaxis.