Changes in lean mass and fat mass in children with Osteogenesis Imperfecta.

BACKGROUND

Deficits in skeletal muscle and function, with resultant abnormal body composition, is a recognised feature of Osteogenesis Imperfecta (OI). Less is known about longitudinal change in body composition in OI. Our objective was to perform a retrospective analysis of longitudinal change in body composition (lean mass and fat mass) in children with OI.

METHODOLOGY: Data was collected from 29 children, with a diagnosis of OI, who had at least two dual-energy x-ray absorptiometry (DXA) scans performed between 2015 and 2022. Assessed variables of height, body mass index (BMI), lean mass index (LMI) and fat mass index (FMI), were converted to z scores. Results were reported as median (range).

RESULTS

Median age at baseline and follow-up were 10.7 and 14.2 years, respectively. Median height z-score at baseline was -1.10, which was significantly lower than a control population (p<0.001). Median height z-score at latest follow-up was -0.80, which was not significantly different from baseline (p=0.870). Median BMI z-score at baseline was 0.15, which was not significantly different than a control population (p=0.804). Median BMI z-score at latest follow-up was 0.02, which was not significantly different from baseline (p=0.730). At baseline, median LMI z-score was -2.43, which was significantly lower than a control population (p<0.001). Median LMI z-score at follow-up was -1.78, which was not significantly different from baseline (p=0.080). At baseline, median FMI z-score was 0.57 which was significantly higher than a control population (p=0.001). Median FMI z-score at follow-up was 0.62, which was not significantly different from baseline (p=0.540).

CONCLUSION

Children with OI have abnormal body composition throughout childhood typically with low lean mass and relatively high fat mass. These abnormalities in body composition do not change with follow-up. Strategies to improve lean mass, including physical or medical therapies, should be explored in OI given the close relationship between muscle and bone.