COMPARISON OF A SEMIQUANTITATIVE AND A QUANTITATIVE METHOD FOR ASSESSING VERTEBRAL FRACTURES IN OSTEOPOROSIS

There is no agreed definition for the assessment of vertebral fractures and deformities in patients with osteoporosis. Radiographs of 66 patients randomized for therapy with etidronate or placebo were analyzed at baseline and during follow-up (60/120/150 weeks) independently using two procedures. The first method of spinal deformity index (SDI(G)) and vertebral deformity score (VDS(G)) is based on a semiquantitative visual reading of each vertebra between T4 and L4. The second method of spine deformity index (SDI(M)) and vertebral deformity index (VDI(M)) is based on vertebral height measurements of T4 through L5 and each measurement from T5 to L5 (anterior, middle and posterior height) is related to T4 and compared with the respective T4-related normal range. There was good agreement between the mean vertebral deformation from T5 to L4 graded by VDS(G) and VDI(M), with correlation coefficients between R=0.52 (p<0.0001) and R=0.9 (p<0.0001) respectively. Spinal deformation at baseline as measured by SDI(M) and SDI(G) was correlated with R=0.76 (p<0.0001). For diagnosing a vertebra as fractured or not, VDI(M) reached a sensitivity of 82% and a specificity of 85% using VDS(G) as a standard, and on the other hand VDS(G) reached a sensitivity of 78% and a specificity of 88% in relation to VDI(M). The changes in spinal deformation from week 0 to 150 were correlated with R=0.58 (p<0.0002) between SDI(M) and SDI(G). To detect vertebral fracture progression the sensitivity of VDI(M) was 74% and the specificity 86%, when changes in VDS(G) were used as a standard. On the other hand sensitivity for VDS(G) was 56% and specificity 95% to detect vertebral fracture progression, when changes in VDI(M) were used as a standard. The comparison of changes in spinal deformation in the etidronate and placebo group during the 3-year study demonstrated that changes in SDI(M) during follow-up confirmed the results found by the changes in SDI(G). As an independent standard for vertebral deformity and fracture definition is not available, the present study does not allow a decision as to whether semiquantitative reading (SDI(G)) or vertebral height measurements (SDI(M)) are closer to the biological truth. We conclude that in clinical studies the assessment of vertebral fractures or deformations should be validated by the comparison between two different established techniques, performed independently.