Leslie WD et al. – Total hip area BMD categorizes a substantially higher fraction of women with smaller bone area as being osteoporotic despite younger age. Incident fracture rates correlate equally well with BMD across all bone area quartiles when adjusted for age. Methods
Whether the skeletal size confounds the use of BMD as a diagnostic and fracture risk assessment tool was tested
16205 women of white ethnicity age 50 y or older undergoing baseline hip assessment with DXA
Total hip measurements were categorized in total hip bone area (Q1=smallest, Q4=largest)
Records were assessed for the presence of non-traumatic osteoporotic fracture codes during f/u after BMD testing
Results
Total hip bone area strongly affected osteoporosis diagnosis with much higher rates in Q1 (14.4%) than Q4 (8.9%)
However, incident fracture rates were constant across all area quartiles and prevalent fractures were paradoxically fewer in smaller area quartiles
Age was a potential confounder that correlated positively with area
Q1 appeared to have a lower rate of incident osteoporotic fractures and hip fractures for a given level of BMD
Total hip BMD was strongly predictive of incident osteoporotic fractures and hip fractures but there was no independent effect of bone area
Bone area had no appreciable effect on incident fractures
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