What proportion of incident radiographic vertebral deformities is clinically diagnosed and vice versa?

We prospectively examined, in a large cohort of older women, the proportion of incident radiographic vertebral deformities diagnosed as incident clinical vertebral fractures in the same women at the same vertebral level. The proportion of deformities clinically diagnosed ranged from <15% for milder deformities to nearly 30% for more severe deformities.

The relationship between radiographic and clinical vertebral fractures is incompletely understood. No previous study has prospectively compared the agreement between incident radiographic vertebral deformities and incident community-recognized, radiographically confirmed vertebral fractures in the same women at the same vertebral level(s).

This analysis of data from the Fracture Intervention Trial included all participants who completed both baseline and at least one scheduled follow-up lateral spinal radiograph (n = 6084). Incident vertebral deformities were defined at a given vertebral level as a reduction between baseline and closeout radiographs of > or = 20% and 4 mm in any vertebral height and subdivided into two severity categories. Incident clinical vertebral fractures were those reported to clinical centers by participants and confirmed by the study radiologist, who compared the community spinal radiograph with the participant's baseline study radiograph using semiquantitative methods.

A total of 446 incident radiographic vertebral deformities were identified in 330 women, whereas 121 women experienced one or more confirmed incident clinical vertebral fracture. Of incident radiograpic vertebral deformities, 22.6% were also clinically diagnosed as incident vertebral fractures, with clinical diagnoses made for 28.4% of the deformities that exceeded 30% and 4 mm height loss (severe deformity) compared with 14.3% for deformities that involved > or = 20% and 4 mm but < 30% height loss (milder deformity). Of incident clinical vertebral fractures, 72.7% were morphometrically identified as incident deformities, most of them as severe deformities. More than 20% of incident clinical fractures were not identified as incident deformities by even the most liberal morphometric criterion used in this study.

Approximately one-fourth of incident radiographic vertebral deformities were clinically diagnosed as new vertebral fractures, although the proportion clinically diagnosed was increased for more severe deformities. Whereas most incident clinical vertebral fractures were identified as severe morphometric deformities, approximately one-fourth did not meet even the most liberal study criterion for morphometric deformity. Further study of factors that may explain the discordance between incident vertebral deformities and incident clinical vertebral fractures is important.