Objective. Autoantibodies have been demonstrated in single serum samples from healthy subjects up to 10 years before they developed rheumatoid arthritis (RA). However, the time course for the development of antibodies before onset of clinical RA is unknown, nor is it known which antibody, or combinations of antibodies, might be most sensitive or specific for predicting future development of the disease. The present study was undertaken to investigate this.Methods. Patients with RA who had been blood donors before the onset of disease symptoms were enrolled. Frozen serum samples from each donor were retrieved, together with 2 serum samples from controls matched for age, sex, and date of donation. All samples were tested for IgM rheumatoid factor (IgM-RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies.Results. Seventy-nine patients with RA (62% female; mean age at onset of symptoms 51 years) were included. A median of 13 samples (range 1-51) per patient were available; the earliest samples had been collected a median of 7.5 years (range 0.1-14.5) before the onset of symptoms. Thirty-nine patients (49%) were positive for IgM-RF and/or anti-CCP on at least one occasion before the development of RA symptoms, a median of 4.5 years (range 0.1-13.8) before symptom onset. Of the 2,138 control samples, 1.1% were positive for IgM-RF, and 0.6% were positive for anti-CCP.Conclusion. Approximately half of patients with RA have specific serologic abnormalities several years before the onset of symptoms. A finding of an elevated serum level of IgM-RF or anti-CCP in a healthy individual implies a high risk for the development of RA. We conclude that IgM-RF and anti-CCP testing with appropriately high specificity may assist in the early detection of RA in high-risk populations.

Patients who later develop rheumatoid arthritis have a considerably more atherogenic lipid profile than matched blood donors at least 10 years before onset of symptoms. As inflammation only marginally explains the differences between the two groups, a modulating effect of lipids on inflammatory processes is hypothesised.

Objective. We previously reported that approximately half of the patients with rheumatoid arthritis (RA) have specific serologic abnormalities (elevated serum concentrations of IgM rheumatoid factor and/or anti-cyclic citrullinated peptide antibodies) starting several years before the onset of symptoms. In this study, the presence of serologic signs of inflammation in patients with preclinical RA was investigated with serial measurements of C-reactive protein (CRP).Methods. Seventy-nine patients (61% female; mean age at onset of symptoms 51 years) who had been blood donors before the onset of RA were identified. Frozen serum samples from each donor were retrieved, together with 1 sample from a control donor matched for age, sex, and date of donation. CRP was measured using a highly sensitive latex-enhanced assay. The dates of donation were categorized into 15 1-year periods preceding the onset of RA symptoms. For each period, the median CRP levels in the patient and control groups were compared using the Mann-Whitney U test. The course of CRP concentrations over time in the patient group was estimated with random coefficient analysis.Results. A median of 13 samples (range 1-51) per patient were available; the earliest donation was made a median of 7.5 years (range 0.4-14.5 years) before the onset of symptoms. A total of 1,078 patient samples and 1,071 control samples were tested. For all 1-year periods, the median CRP concentration was increased in the patient group compared with the control group, but this difference was statistically significant only for the periods 0-1 year, 1-2 years, and 4-5 years before the onset of symptoms. The CRP concentration increased significantly over time in patients with preclinical RA; levels were slightly higher in the group of patients who had serologic abnormalities before the onset of symptoms than in those without such serologic abnormalities. Conclusion. After observing specific serologic abnormalities 5 years before the onset of RA symptoms, we now report increased levels of CRP in blood donors in whom RA later developed; these increases were most common within the 2 years before the onset of symptoms. The preclinical increase in CRP levels was observed both in donors with and in those without serologic abnormalities.

Background: The anti-cyclic citrullinated peptide (CCP) test has a high sensitivity and specificity for rheumatoid arthritis, although CCP is not the physiological target of the autoantibodies. Citrullinated fibrin is abundant in inflamed synovium Objective: To assess the diagnostic and prognostic value of antibodies against citrullinated fibrinogen (ACF), a soluble precursor of fibrin, in comparison with IgM-rheumatoid factor (IgM-RF) and the second generation anti-CCP test. Methods: In 379 patients with early arthritis (258 rheumatoid and 121 undifferentiated), the sensitivity, specificity, and positive predictive value of ACF, anti-CCP, and IgM-RF for diagnosing rheumatoid arthritis were calculated. Multivariate logistic regression analysis was used to assess the diagnostic and prognostic value (radiographic progression after two years) of the tests. Results: The sensitivities of the ACF, anti-CCP, and IgM-RF tests were 55.8%, 57.8%, and 44.6%, with specificities of 92.6%, 94.2%, and 96.7%, respectively. Approximately 30% of the IgM-RF negative patients were positive for ACF or anti-CCP or both. The ACF and anti-CCP test had a high agreement in early arthritis (k = 0.84). Of all baseline characteristics, the ACF test and the anti-CCP test were the best predictors for diagnosing rheumatoid arthritis at one year (odds ratio (OR) = 10.3 and 10.6, respectively) and for radiographic progression after two years (OR = 12.1 and 14.8). Conclusions: ACF is as sensitive as anti-CCP and more sensitive than IgM-RF in diagnosing rheumatoid arthritis in early arthritis. The ACF test is also a good predictor of radiographic progression, with a performance similar to the anti-CCP test. The ACF test and the anti-CCP test are especially valuable in IgM-RF negative arthritis.

Both the acute phase response and autoantibody formation often develop years before the first symptoms of RA occur, and these phenomena are probably closely connected in time.