Background/Purpose: Biomarkers in patients with rheumatoid arthritis (RA) have the attractive potential to help select patients that have a greater burden of disease activity and might have better treatment response when starting a new RA medication. This feature may be relevant both as inclusion criteria for a clinical trial or for clinical care.

Methods: We used Corrona, a large longitudinal registry of U.S. patients with rheumatoid arthritis that has been collected by more than 625 rheumatologists in 40 states. To be eligible for this analysis, patients had to be initiating one of 8 biologic DMARDs (adalimumab, etanercept, certolizumab pegol, golimumab, infliximab, abatacept, tocilizumab, rituximab) or tofacitinib  and have a MBDA score processed no more than 6 months prior or 1 month after their initiation date.  We evaluated CDAI at the corresponding 2 CORRONA visits: a baseline visit no more than 6 months prior to the initiation date (‘baseline’) and a follow-up CORRONA visit within 3-9 months subsequently. Patients also must have had baseline high disease activity as measured clinically using the CDAI (>22). Demographic and clinical variables at baseline were tested to determine their association with the MBDA score.  General linear model analysis with change in CDAI between baseline and follow-up as the main outcome were evaluated according to MBDA category [low (<30), medium (30-44), and high (>44)], controlling for age, body mass index, and CDAI at baseline.

Results: There were 74 patients with baseline MBDA scores available that initiated a new medication that also had longitudinal follow-up data. Characteristics of these patients were median (IQR) age 61 (50,71) years, 76% women, 91% white; 14% with diabetes, 11% fibromyalgia, 11% current smokers, and 72% seropositive. Median (IQR) BMI was 30; CDAI 33 (36, 39); CRP 5.2 (2.3,15.2) mg/L; and MBDA score 45 (36-60). Patients with higher MBDA scores (>44) had greater crude mean change in CDAI (-15.5 units) compared to mean change in CDAI (-7.6 units) in those with low or medium MBDA scores. After adjusting for age, BMI, and baseline CDAI, patients in the high MBDA category had a mean 8 unit incrementally greater improvement in the CDAI (p < 0.01) compared to patients with baseline MBDA scores in the low to moderate range.

Conclusion: Among RA patients with high disease activity clinically who started a new medication for RA, MBDA scores in the high range (>44) were associated with significantly greater improvement in the CDAI over time compared to those starting with lower MBDA scores. The MBDA test may be useful to select patients who subsequently have a better response to treatment and thus provide utility even beyond clinical assessments of RA disease activity such as the CDAI.