The reliability of radiologic findings for differential diagnosis of vertebral osteoporosis

BACKGROUND: Radiologically identified vertebral deformities, e.g. wedge-, fish-, or crush-vertebrae are not always a consequence of local osteoporosis. Other frequent pathomechanisms include Morbus Scheuermann, degenerative changes, overt trauma, and congenital dysplasia. This requires differential diagnosis of vertebral deformities. Radiological classification criteria have to satisfy various methodological requirements to ensure reliability of the results. METHODS: Inter-rater reliability of more than 30 radiological findings was assessed in 4 German centres of the European Vertebral Osteoporosis Study (EVOS). One hundred randomly selected EVOS cases from the West-Berlin population, each contributing 2 lateral X-rays from the thoracic and lumbar spine respectively, were independently evaluated by 7 observers. All observers were medical doctors, 4 of them heads or members of clinical radiological departments. Thus each observer read 200 radiographs. Radiological alterations in the form and structure of 13 vertebrale which were considered to be relevant for the differential diagnosis of osteoporosis were recorded in a standardized documentation form. Additionally global judgements (e. g. "osteoporotic spine" yes/no) were required. To quantify agreement Fleiss' kappa (kappa) for nominal data and multiple observers was used.