Comparison of morphometric assessment of prevalent vertebral deformities in women using different reference data

The semiquantitative assessment of vertebral deformities is based on visual evaluation. The quantitative approach is based on different morphometric c riteria. This study is aimed at comparing the impact of different reference groups to define normal vertebral shape on the diagnosis of verterbral def ormities. Reference normal values were obtained in three groups of women: F rench, mixed European, and Argentinian, All these women had normal lumbar s pine bone mineral density and no vertebral deformities according to the sem iquantitative assessment. In a group of 135 women having vertebral deformit ies according to Genant's semiquantitative assessment, three different morp hometric criteria were applied. Morphometric diagnosis disclosed a good agr eement with semiquantitative assessment. Agreement of diagnosis was higher for a given cutoff using thresholds obtained in different reference groups (kappa = 0.84-0.96) and lower when different criteria were compared using t hresholds obtained in the same reference group (kappa = 0.75-0.85), When fr acture thresholds obtained in three different cohorts were compared separat ely for the three morphometric criteria, agreement was the highest when the cutoff was based only on the arithmetical mean of vertebral heights and wa s independent of its standard deviation (SD), Average vertebral height rati os did not differ between the three reference cohorts, whereas SDs of verte bral height ratios were the highest in the mixed European cohort and the lo west in the French cohort (F = 7.41, p < 0.001), In the three groups of wom en of different nationality, SDs of vertebral height ratios, but not the ar ithmetical means, were significantly higher in the radiographs of poor qual ity compared with those of good quality. Thus, the main source of differenc e of diagnosis was related to different SDs whereas average height ratios w ere not different. Differences in SDs between the three groups were found t o be related, at least partly, to poor quality of radiographs. The impact o f the differences between populations seems less important, however, only t hree countries were compared. These findings suggest that those techniques that take into account the SD of vertebral height ratios will provide diffe rent reference values for vertebral morphometry. Because differences in SDs depend mainly on the quality of radiographs, they can be reduced by improv ing the X-ray technique and by the use of standardized protocols. This vari ability will result in the identification of a variable number of vertebral deformities in osteoporotic women. These results may be of importance espe cially for multicentric studies. (C) 2000 by Elsevier Science Inc, All righ ts reserved.