Extra-articular disease manifestations in RA: incidence trends and risk factors over 46 years

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ls of the Rheumatic Diseases 2003;62:722-727

© 2003 by BMJ Publishing Group & European League Against Rheumatism

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EXTENDED REPORT

Extra-articular disease manifestations in rheumatoid arthritis:

incidence trends and risk factors over 46 years

C Turesson1, W M O'Fallon2, C S Crowson2, S E 2 and E L Matteson3

1 Department of Rheumatology, Malmö University Hospital, Lund

University, Sweden

2 Department of Health Sciences Research, Mayo Clinic and Mayo Graduate

School of Medicine, Rochester, Minnesota, USA

3 Division 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;

turesson.carl@...

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.