The frequency of erosiveness was studied in rheumatoid arthritis (RA) by longterm followup.
A community based cohort of 263 patients with recent onset (< or = 6 months) arthritis were followed in Heinola. At 8-year followup examination 113 cases were found to have rheumatoid factor positive (seropositive) nonspecific arthritis, and 15 were nonerosive in the radiographs. The 15 patients were reexamined in 1992 (17-year followup).
Eleven of 15 were found to have erosive disease, and of these, 6 had putative psoriatic arthritis, 4 RA, and one monoarthritis of the knee. Of the remaining 4 seropositive nonerosive cases only one fulfilled the 1987 American College of Rheumatology (ARA) criteria for RA.
In patients with seropositive RA with 4 1987 ARA criteria, 99% developed erosive disease.