Reliability of vertebral fractures assessment (VFA) in children with osteogenesis imperfecta

The aim of this study is to evaluate the diagnostic accuracy of vertebral fractures assessment (VFA) in comparison with conventional radiography in identifying vertebral fractures in children and adolescents affected by OI. On 58 patients (33 males, 25 females; age range 1-18 years; 41 children and 17 adolescents) with osteogenesis imperfecta (OI type I, n = 44, OI type III, n = 4; OI type IV, n = 10), lateral spine images by radiographs and by dual-energy X-ray absorptiometry (DXA) were acquired. For vertebral fracture diagnosis, plain radiographs were used as "gold standard" and VFA and morphometric X-ray absorptiometry (MXA) were performed. The visualized vertebrae were 738 (97.9%) by radiographs and 685 (90.9%) by DXA of a total of 754 vertebrae from T4 to L4. VFA and MXA identified, respectively, 129 (74%) and 116 (66%) of the 175 vertebral fractures detected by radiographs. Radiographs identified 36 patients with vertebral fractures, VFA 35 and MXA 41 (6 false positives). On a per vertebra basis, radiographs and VFA had elevated agreement (93.9%; k score 0.81, 95% CI 0.76-0.86), that resulted slightly lower for MXA (90.6%; k score 0.72, 95% CI 0.65-0.78). VFA and MXA demonstrated high sensitivity (95.6 and 94.1 %, respectively) while specificity was 100% for VFA and 90.6% for MXA on a per patient basis; the agreement was excellent for VFA (98.3%; k score 0.96, 95% CI 0.89-1.03) and good for MXA (87.9%; k score 0.73, 95% CI 0.55-0.91). The diagnostic performance parameters resulted better for VFA (sensitivity 95.6%; specificity 100%; PPV 100%; NPV 97.2%), than for MXA (sensitivity 94.1%; specificity 85.4%; PPV 72.7%; NPV 97.2%). The results of our study demonstrate the reliability of VFA for diagnosis of vertebral fractures in children with OI suggesting its use as a more safe and practical alternative to conventional radiography.