Because single-center studies have reported conflicting associations between microarchitecture and fracture prevalence, we included HR-pQCT data from 5 centers worldwide into a large multicenter analysis of postmenopausal women with and without fracture. Volumetric density (vBMD) and microarchitecture were assessed at the distal radius and tibia in 1379 Caucasian postmenopausal women (67±8 yr); 470 (34%) had at least one fracture including 349 with a major fragility fracture.
Age, height, weight, and total hip T-score differed across centers and were employed as covariates in analyses. Women with fracture had higher BMI, were older, and had lower total hip T-score but lumbar spine T-score was similar between groups.
At the radius, total and trabecular vBMD and cortical thickness were significantly lower in fractured women in 3 out of 5 centers, and trabecular number in 2 centers. Similar results were found at the tibia. When data from 5 centers were combined, however, women with fracture had significantly lower total, trabecular and cortical vBMD (2%–7%), lower trabecular number (4%–5%) and thinner cortices (5%–6%) than women without fracture after adjustment for covariates. Results were similar at the radius and tibia. Similar results were observed with analysis restricted to major fragility fracture, vertebral and hip fractures and peripheral fracture (at the radius). When focusing on osteopenic women, each SD decrease of total and trabecular vBMD was associated with a significantly increased risk of major fragility fracture (OR=1.55–1.88, p<0.01) after adjustment for covariates. Moreover, trabecular architecture modestly improved fracture discrimination beyond peripheral total vBMD.
In conclusion, we observed differences by center in the magnitude of fracture/non fracture differences at both the distal radius and tibia. However, when data were pooled across centers and the sample size increased, we observed significant and consistent deficits in vBMD and microarchitecture independent of total hip T-score in all postmenopausal Caucasian women with fracture and in the subgroup of osteopenic women, compared to women who never had a fracture.