In a real-world registry of patients with rheumatoid arthritis (RA), scores on the multi-biomarker disease activity (MBDA) test were significantly associated with RA disease activity, obesity, and age, but were not significantly linked with common comorbidities in this population, according to an analysis published in Seminars in Arthritis and Rheumatism.1

Although traditional markers of inflammation are usually required for inclusion in RA clinical trials, patients with active disease may have normal laboratory test results. For the current study, the investigators accessed data from the Corrona registry to conduct a cross-sectional analysis of patients with RA and MBDA test results. Participants were characterized based on MBDA test scores (categorized as low [score <30], moderate [score between 30 and 40], and high [score >44]),2 presence of C-reactive protein (CRP), erythrocyte sedimentation rate, swollen joint count, and Clinical Disease Activity Index (CDAI). Regression was used to evaluate the association between MBDA score and age, body mass index (BMI), comorbidities, and RA-related factors.

A total of 357 patients were eligible for the study. Overall, 273 (76%) participants had normal CRP levels (<10 mg/mL). Levels of disease activity based on MBDA score were rated as high for 33% of study participants, moderate for 45%, and low for 22%. MBDA score was significantly associated with BMI (P =.004), age (P =.0001), CDAI (P <.0001), and swollen joint count (P =.001). In contrast, no significant association was reported between MBDA score and several RA comorbidities, including fibromyalgia, diabetes, smoking, and chronic obstructive pulmonary disease.


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In patients whose disease was in remission (based on CDAI; n=74), older age (P =.03) and obesity (BMI >30; P =.02) were both significantly associated with higher MBDA scores, but female gender and BMI >25-30 were not. 

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“In this real-world RA registry, the MBDA score was associated with RA disease activity and was negligibly affected by comorbidities common to RA patients, although [it] was affected by obesity (proxied by BMI) and age,” concluded the researchers.

Nearly one-third of those with normal CRP levels had high MBDA scores. The investigators proposed that an adjustment be made to the MBDA score to account for BMI and age.

References

1. Curtis JR, Greenberg JD, Harrold LR, Kremer JM, Palmer JL. Influence of obesity, age, and comorbidities on the multi-biomarker disease activity test in rheumatoid arthritis [published online August 2, 2017]. Semin Arthritis Rheum. doi: 10.1016/j.semarthrit.2017.07.010

2. Centola M, Cavet G, Shen Y, et al. Development of a multi-biomarker disease activity test for rheumatoid arthritis. PLoS One. 2013;8(4):e60635.