A new study in The Journal of Haemophilia Practice found differences in bone mineral density (BMD) between children with severe hemophilia and healthy controls.
“Canadian children with severe hemophilia 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,” the authors wrote
Most (79%) hemophilia patients had lower total body BMD than healthy controls. The mean difference in total body BMD was -0.7647 (95% CI, -1.06909, -0.4604, P <.001). The Z-score was <-2.0 in 6 (18%) patients, whereas the height-age-weight-adjusted score (HAW-score) was <-2 in 3 (9%).
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Moreover, hemophilia patients showed a mean difference of 0.4189 (95% CI, 0.0680, 0.7698, P =.206) in spine BMD when compared with healthy controls. None of the patients presented with a spine Z-score or HAW-score of <0.
The authors found an association between low intake of vitamin D and low hip and spine BMD Z-score and HAW-score. In addition, patients with a Hemophilia Joint Health Score (HJHS) greater than 0 presented with a higher total body HAW-score compared to those with a joint score of 0.
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On the other hand, hip scores were similar between the 2 groups (mean difference, -0.0171, 95% CI, -0.4977, 0.4634, P =.9426), with 2 patients (0.5%) showing a Z-score and HAW-score inferior to -2.
The authors found no association between BMD Z-score or HAW-score and factor replacement regimen, Hemophilia Joint Health Score (HJHS), calcium intake, or level of physical activity.
Bos et al used 2 scoring systems: the Z-score and the HAW-score. “The Z-score is the number of standard deviations above or below the mean BMD for age- and sex-matched controls,” they explained. It is used in the pediatric population to describe the BMD, which is quantified through dual-energy X-ray absorptiometry (DXA).
However, the Z-score does not take into consideration deviations in body size (which was shown to affect the interpretation of measured BMD in about 17.5% of children) and its use may lead to an overdiagnosis of osteoporosis. The HAW-score was developed to overcome this issue.
Reference
Bos C, Tieu P, Wu JK, Strike K, Chan AK. Bone mineral density in Canadian children with severe haemophilia A or B: a cross-sectional study. J Haemoph Pract. 2021;8(1):111-118. doi:10.2478/jhp-2021-0012
