To describe the occurrence of different rheumatic diseases and to examine the characteristics of patients referred to six Italian rheumatological units. To compare these data with those from other countries.
Six Italian rheumatological tertiary referral centers participated in the study. Diagnoses of in- and outpatients aged over 16 years were classified according to the International Classification of Diseases, ninth revision.
Three thousand, five hundred and thirty-seven patients with mean age 56 +/- 14.8 years, of which 2604 (73.6%) were women, were studied. Inflammatory joint and spine diseases were diagnosed in 40.4%, connective tissue diseases in 14.4%, degenerative joint and spine diseases in 21.4%, soft tissue rheumatisms in 18.5%, and metabolic bone diseases in 5.3%. There was a significant difference among centers in the frequency of most diagnoses: non-academic centers cared for more patients with arthritis and connective tissue diseases and for less patients with degenerative diseases, soft tissue rheumatisms and metabolic bone diseases. Connective tissue diseases were constantly seen more often in Italian centers, whereas soft tissue rheumatisms were seen more often abroad.
Our data emphasize the great variability of the diagnostic case-mix in different centers from the same country, an observation that raises some concerns of the results of descriptive multicenter studies. Studies on the breakdown of diagnoses made in rheumatological centers could be helpful to determine the burden of rheumatic diseases on the health system, and for the planning of health interventions by both the national rheumatological societies and health authorities.