Diagnostic/Classification Criteria

Abstract

Diagnostic criteria are used, as the name suggests, to make diagnosis of disease. They should encompass those characteristics that we find in every patient with the disease they are designed for. Therefore, it is extremely difficult to design such criteria. Classification criteria, on the other hand, are intended to be used only in already diagnosed patients, to classify them as having the respective disease, mainly for research purposes. Nevertheless, since classification criteria encompass those characteristics of the disease that are present in the majority of patients, it is only natural to try to use them as a helping tool in the diagnostic endeavor. This should be done appropriately, bearing in mind that the patient not fulfilling every one of them, can and may be still diagnosed as having ankylosing spondylitis, even though he/she cannot be classified as such. Classification criteria for ankylosing spondylitis (AS) have changed over time, due to the new insight obtained into the pathogenic mechanisms of the disease. Moreover, a patient fulfilling them is sometimes the initial step mandated by the paying authorities for reimbursement of therapies. All these reasons and others highlight the need to understand the different facets of the diagnostic/classification criteria and their best use.