Comparison of composite measures of disease activity in an early seropositive rheumatoid arthritis cohort

Objective: To evaluate concordance and agreement of the original DAS44/ESR-4 item composite disease activity status measure with 9 simpler derivatives when classifying patient responses by European League of Associations for Rheumatology(EULAR) response, using an early rheumatoid factor positive(RF+) rheumatoid arthritis(RA) patient cohort. Methods: DMARD-naive RF+ RA patients(n=223,mean duration of symptoms,6 months) were categorized as ACR none/20/50/70 responders. One-way analysis of variance and two sample t-tests were used to investigate the relationship between the ACR response groups and each composite measure. EULAR reached/change cut-point scores were calculated for each composite measure. EULAR(good/moderate/none) responses for each composite measure and the degree of agreement with DAS44/ESR-4 item were calculated for 203 patients. Results: Patients’ were mostly female(78%) with moderate to high disease activity. A percentile-based nomogram compares equivalent composite measure scores. Changes from baseline in the composite measures in patients with ACR none were significantly less than those of ACR20/50/70 responders, and those for ACR50 were significantly different than for ACR70. EULAR reached/change cut-point scores for our cohort were similar to published cut-points. When compared to DAS44/ESR-4 item, EULAR(good/moderate/none) percent agreements included 92% with DAS44/ESR-3 item, 74% with CDAI, and 80% each with DAS28/ESR-4 item, DAS28/CRP-4 item, and SDAI. Conclusion: We describe the relationships of 9 different RA composite measures against DAS44/ESR-4 item when applied to a cohort of early sero-positive RA patients. Each of these simplified status and response measures could be useful in assessing RA patients, but the specific measure selected should be pre-specified and described for each study.