Extra-articular disease manifestations in rheumatoid arthritis: incidence trends and risk factors over 46 years
- 1Department of Rheumatology, Malmö University Hospital, Lund University, Sweden
- 2Department of Health Sciences Research, Mayo Clinic and Mayo Graduate School of Medicine, Rochester, Minnesota, USA
- 3Division of Rheumatology, Mayo Clinic and Mayo Graduate School of Medicine, Rochester, Minnesota, USA
- Correspondence to:
Dr C Turesson, Rheumatology Laboratory, 401 Guggenheim, Mayo Clinic, 200 First Street SW, Rochester, 55905 Minnesota, USA;
- Accepted 21 January 2003
Objective: To investigate the trends in incidence of extra-articular rheumatoid arthritis (ExRA) in a well defined community based cohort of patients with rheumatoid arthritis (RA), and to examine possible predictors of ExRA occurrence.
Methods: Using the resources of the Rochester Epidemiology Project, a retrospective medical record review was conducted of a cohort of 609 cases of RA in Olmsted County, MN, diagnosed during 1955–94. These cases had been previously classified using the ACR 1987 criteria for RA. Patients were followed up from 1955 to 2000 (median follow up 11.8 years; range 0.1–42.8), and incident ExRA manifestations were recorded according to predefined criteria. Time to first presentation of ExRA was compared in patients with RA by decade of diagnosis. Possible ExRA risk factors were identified in case record reviews.
Results: ExRA occurred in 247 patients (40.6%). A subgroup of 78 patients (12.8%) had ExRA manifestations considered to be severe in a previous study from Malmö, Sweden. The incidence of severe ExRA did not change significantly over the decades (p=0.165). In a multivariate analysis the main predictors of severe ExRA were smoking at RA diagnosis (risk ratio (RR)=2.94; 95% confidence interval (95% CI) 1.68 to 5.13) and early disability (Steinbrocker class III-IV at diagnosis) (RR=2.45; 95% CI 1.51 to 4.00). The effect of smoking overwhelmed the weaker effect of rheumatoid factor seropositivity.
Conclusion: There was no decrease in the incidence of extra-articular manifestations in patients with RA diagnosed up to 1995. Smoking and early disability are independent risk factors for extra-articular RA.
- ACR, American College of Rheumatology
- ANA, antinuclear antibodies
- CI, confidence interval
- ExRA, extra-articular rheumatoid arthritis
- RA, rheumatoid arthritis
- RF, rheumatoid factor
- RR, relative risk