Problems in examination surveys of the rheumatic diseases.

Examination surveys to document the frequency and distribution of the rheumatic diseases in populations were largely pioneered by the efforts of Kellgren and Lawrence in England starting in the 1950s. The purpose of these surveys was primarily to gain insight into the extent and types of rheumatic diseases and their associated morbidity in representative population samples. From such studies the relative frequency of the common rheumatic diseases was defined and their occurrence in relation to their age and sex distribution within the population described. The methodologies devised for this purpose contained detailed historical, clinical, radiological, and serological components which were then applied by a number of investigators in different countries. The results of these surveys raised questions concerning diagnostic criteria, and led to the realization that diagnostic categorization in the population at large was often more difficult than in the rheumatology clinic.