Developing new classification criteria for diffuse idiopathic skeletal hyperostosis: back to square one

Abstract

Objective: To revise the definition of DISH and suggest a classification that may better represent our current knowledge of this entity allowing earlier diagnosis.

Methods: Seven rheumatologists and an orthopaedic surgeon suggested a list of 63 parameters that might be included in a future classification of DISH. Participants rated their level of agreement with each item, expressed in percentages. In a second session, participants discussed each item again and re-rated all parameters. Thirty items that were granted ≥50% support on average were considered valid for a third round. A questionnaire listing these 30 items was mailed to 39 rheumatologists and orthopaedic surgeons worldwide with a request to answer categorically if they agreed on an item to be included as a criterion for a future classification of DISH. Items were regarded as perfect consensus when at least 95% of the respondents agreed and were regarded as consensus when at least 80% agreed.

Results: There was perfect consensus for 2 (6.7%) of the 30 parameters and consensus for another 2 parameters. These items were ossification and bridging osteophytes in each of the three segments of the spine and exuberant bone formation of bone margins.

Conclusion: At present there is no agreement about the inclusion of extraspinal, constitutional and metabolic manifestations in a new classification of DISH. Investigators with an interest in this condition should be encouraged to restructure the term DISH in an attempt to establish a more sophisticated definition.