The impact of height on low/reduced bone mineral density in Chinese adolescents aged 12-14 years old: gender differences

Low/reduced bone mineral density (BMD) is an important predictor of childhood fracture. In this article, we presented the prevalence of BMDin Chinese adolescents and, for the first time, demonstrated the gender disparities in the impact of height on BMD.PurposeTo analyze the gender disparities in the association of low/reduced BMDwith height in Chinese adolescents at the stage of growth spurt.MethodsA total of 8152 adolescents aged 12-14years old were included based on a cross-sectional study in Tianjin, China. Height and weight were measured with standard equipment. BMD was measured using the method of quantitative ultrasound. Adolescents with Z <=-2.0 or -2.0<Z <=-1.0 were defined as low BMD or reduced BMD.ResultsThe total low/reduced BMD rate was 22.0% in Chinese adolescents aged 12-14years old, and boys were more likely to have low/reduced BMD than girls (30.1% vs. 12.9%, P<0.001). The rate of low/reduced BMD significantly increased with age in boys (P-trend=0.019), whereas decreased with age in girls (P-trend=0.018). We found significant interaction effect between gender and height standard deviation score (height-Z)in the association with low/reduced BMD (P-interaction<0.001). There was a positive association of height-Z among boys (OR=1.30, 95%CI 1.21-1.39, P<0.001), meanwhile low/reduced BMD was inversely associated with height-Z among girls (OR=0.85, 95%CI 0.78-0.94, P<0.001).ConclusionsOur study suggested strong gender disparities in the impact of height on BMD in Chinese adolescentsaged 12-14 years old, where the association between low/reduced BMD and height was positive among boys but inverse among girls. The study provides evidence on the early prevention and the risk factor identification of low/reduced BMD and childhood fractures.