Can a simple 0-10 RheuMetric physician estimate of inflammatory activity (DOCINF) depict a detailed swollen joint count (SJC) as accurately as a DAS28 or CDAI in patients with rheumatoid arthritis?

OBJECTIVE

To compare a 0-10 physician subglobal estimate of inflammatory activity (DOCINF) on a RheuMetric checklist to a formal swollen joint count (SJC) and other rheumatoid arthritis (RA) Core data set measures in a disease activity score 28 (DAS28), clinical disease activity index (CDAI), and simplified disease activity index (SDAI) in patients with RA, recognizing that RA measures, index scores and physician global assessment (DOCGL) may be elevated by joint damage and patient distress, independent of inflamamtory activity, and that formal joint counts are not recorded at most routine care visits.

METHODS

A cross-sectional study at a routine care visit included a RheuMetric checklist completed by a rheumatologist, with four 0-10 visual numeric scales (VNS) for DOCGL, and three sub-global estimates for inflammatory activity (DOCINF), joint damage (DOCDAM), and patient distress (DOCDIS), e.g., anxiety, depression, and/or fibromyalgia, etc. Variation in SJC according to other individual measures in the DAS28, CDAI, and SDAI, and in the indices was analyzed using Spearman correlation coefficients and regressions with and without DOCINF as an independent variable.

RESULTS

In 173 patients with long disease duration, regressions which included individual DAS28, CDAI or SDAI measures and added DOCINF as an independent variable explained 46 % of variation in SJC, compared to 23 % if DOCINF was not included. DOCINF was more explanatory of SJC than even the DAS28 or CDAI indices themselves, although SJC is a component of these indices.

CONCLUSION

In routine care RA patients with long disease duration, DOCINF depicts SJC as effectively as RA indices which require 90-100 seconds to record, and may provide a feasible, informative quantitative clinical measure without recording formal joint counts.