Even though there has been a tremendous increase in our medical knowledge during the 20th century there are still diseases in which we do not yet understand the etiology and the involved pathophysiological mechanisms. Furthermore, the medical profession sometimes has difficulties in differentiating disorders as various patient categories might have similar although not identical symptoms. It is only possible to offer rational pharmacotherapy if the diagnostic procedures can discriminate between the closely related diseases because even closely related disorders often require different therapy. This is especially true within the systemic chronic rheumatic diseases in which there is a great need for internationally accepted classification criteria but such criteria does not exist today.
Pitfalls are, however, evident.
Much argumentation and concerns have dealt with the discrepancy between the subjective symptoms and the objective data. So, these criteria will have no difficulties in including patients without subjective ocular and oral complaints. This lack of subjective complaints in spite of severely impaired laboratory tests is rather common in young adults and even more evident in children. If subjective symptoms are to be used as part of the classification criteria it must be remembered that there can be many symptoms. However, objective tests for stomatitis sicca are fewer and not quite similar to the ocular tests.