Background The presence of high acute phase reactants may help the diagnosis and classification of patients with rheumatoid arthritis, specially in seronegative patients.
Objectives Our objective was to establish if the presence of high basal reactants in early arthritis may help to establish the diagnosis of rheumatoid arthritis following criteria of ACR 1987 (which does not include positive reactants in diagnostic criteria). at 12 months of follow-up.
Methods The presence of acute phase reactants at the baseline visit (elevated CRP and elevated ESR according to two different criteria) was studied in a population of 70 patients referred to the arthritis clinic with criteria for suspicion of early arthritis to meet at least one of the Following criteria: a) Swelling in 2 or more joints b) Pain in MCFs, MTFs and/or wrists c) Morning stiffness greater than 30 minutes (* SERAP study criteria), with <12 months of evolution of symptoms. None of the patients had previous diagnosis of rheumatoid arthritis or other inflammatory joint disease nor had previous treatment with steroids or DMARDs. The presence of high VSG (mm/h) was considered according to two criteria: a) ESR 1: VSG>20 or b) ESR 2 (criterion according to age and sex) (1): Age ≥50 years ESR>20 in men and ESR>30 in women; Age <50 years of age, ESR>15 mm/h in men and>20 in women.Statistics: Chi-square or Fisher test (for any value <5), Odds ratio (OR) calculation.
Results 70 patientes, 45 women (64,3%), x age 51,57±16,08 y (18–85) were included, x disease duration 3,47 meses ± 2,59 (0,53–11.73), 48/70 (68,5%) RF and ACPA negative. 49 patients meet ACR 1987 criteria, but 5 were finally classified in non-RA group because they meet criteria of other inflammatory chronic articular conditions (eg. psoriatic arthritis RA-like). 45/70 patients had high baseline CRP (64.3%), ESR 1 38/70 (54.3%) and ESR 2 35/70 (50%). Basal CRP>5 showed statistically significant differences for RA diagnosis (ACR 1987 criteria) p=0.003, OR =4,64 (1.62–13,24) but basal positive ESR 1 criteria did not (p=0.122). Basal positive ESR2 showed significant differences for diagnosis of RA, with p=0.036, OR =2,78 (0,99–7,47). In the subgroup of seronegative patients, basal CRP could predict ACR 1987 RA diagnosis at 12 months follow-up p=0,019, OR 4,2 (1,23–14,36), but ESR (both ESR1 and ESR2) not (p=1,000). If the 5 patients ACR 1987 meeting criteria RA-like but diagnosed ot other inflammatory conditions were included, the results are similar but ESR2 reached a better confidence interval p=0.036, OR 3,63 (1,20–10,94).
Conclusions The presence of elevated basal CRP>5 may be used as a factor that helps to predict the diagnosis of rheumatoid arthritis according to ACR 1987 criteria for RA. The baseline elevated ESR according to the sex and age criterion could be useful as a predictor factor for the diagnosis of rheumatoid arthritis, while the VSG criterion>20 in all patients does not demonstrate differences in the study between the two groups with final diagnosis AR and non-RA. In seronegative patientes, only CRP demostrated predictive value but ESR not.
Bottiger LE, Svedberg CA. Normal erythrocyte sedimentation rate and age. Br Med J 1967; 2:85–7.
Disclosure of Interest None declared