Comprehensive radiographic evaluation of diffuse idiopathic skeletal hyperostosis: development and interrater reliability of a scoring system.

OBJECTIVE

To develop a scoring system for radiographic findings in diffuse idiopathic skeletal hyperostosis (DISH) and to test interrater reliability.

MATERIALS AND

METHODS

Fifty-five DISH patients and 35 spondylosis patients underwent two views (anteroposterior and lateral) of the cervical, thoracic, and lumbar spine, lateral views of both ankles, knees, and elbows, and anteroposterior views of the pelvis and shoulders. Two raters reviewed and scored the x-rays. Interrater reliability was assessed with the alpha statistic (alpha) for categorical variables and with the intraclass correlation coefficient (ICC) for continuous variables.

RESULTS

The agreement was similar for the three spinal segments (alpha = 0.44 to 0.71). The lower extremity agreement ranged from 0.28 to 0.76, with higher agreement at the knee (alpha > or = 0.46) and the ankle (alpha > or = 0.56) than at the pelvis (ICC < or = 0.58). The agreement at the shoulders and elbows ranged from 0.50 to 0.75. The agreement between the readers was higher with summary measurements than with single (site-by-site) measurements: for each spinal segment, the ICC was 0.83 or greater; for the lower extremity, the ICC = 0.79; and for the upper extremity, the ICC = 0.68.

CONCLUSION

We have described a comprehensive scoring system to assess the spinal and peripheral involvement of DISH.