Utilization of multiple disease activity measures in rheumatoid arthrtis patients detected a unique subtype of rheumatoid arthritis

Background: Routinely performing disease activity measures (DAMs) in a rheumatology clinic setting is required for proper decision making concerning treatments and for diagnostic purposes. The choice of the ideal combination of DAM instruments has yet to be determined. The most common instruments currently employed, such as the disease activity score in 28 joints (DAS28-CRP), can lead to spurious results because of subjective patient impact on such items as joint counts. Including more diverse methods that determine disease activity by non-clinical means would seem of possible benefit in this setting. The ultrasound power Doppler joint count (UPDJC) and multiple biomarker disease activity (MBDA) blood test are two possible options. Objectives: To use diverse DAMs in a rheumatology clinic to facilitate decision making and diagnosis. Methods: All patients with a diagnosis of rheumatoid arthritis in a long-standing rheumatology clinic underwent evaluation with DAMs including the DAS28-CRP, and blood testing with a MBDA (Crescendo). Also, a method for preforming a truncated UPDJC was adopted [1] utilizing a subjective 0 (normal) to 3 (severe) scoring system leading to a possible score of (0-36). Results: There were 262 patients tested with all three DAMs in the clinic. The correlations between the UPDJC and DAS28CRP and MBDA were r=0.52 and r=0.58 respectively and the correlation between the DAS28CRP and MBDA was r=0.58. However, eleven patients (4%) stood out as outliers. These patients all had low disease activity (LDA) or no disease activity (NDA) as demonstrated by the UPDJC and the MBDA, but showed moderate disease activity (MDA) to moderate-high disease activity by the DAS28-CRP. When the DAS28-CRP was broken down into its individual components, all of these patients showed high values for painful joint counts and patient global assessments. When these eleven patients were assessed for joint morphology by ultrasound grey scale, all patients showed several joints with enlarged, distended (dissected) joint capsules. All these patients also related a clinical history of having to perform physically demanding work while they were having high levels of disease activity. Conclusions: • The use of a diverse panel of DAMs in a rheumatology setting detected rare (4%) patients with a unique profile. • These patients demonstrated significant disease activity by clinical assessments but not by two different objective measures of inflammation. • These patients would not be expected to respond to changes in their disease-modifying antirheumatic drugs. • These patients would superficially appear to be good candidates for drug studies, but would not be expected to respond and should not be entered into clinical trials.