Background/Purpose: Periodic measurement of disease activity using validated tools such as the Clinical Disease Activity Index (CDAI) is considered an important aspect of care for patients with rheumatoid arthritis.  Treat to target strategies mandating changes in therapy to achieve low disease activity measures have been well studied.  However, much less is known about the use of these measures and the influence on physician behavior in routine clinical practice.

Methods: Seventy nine rheumatologists from 35 practices in the mid-Atlantic participated in a payer sponsored rheumatologist developed RA treatment clinical pathway which required CDAI measurement at each visit.  To be considered compliant with the pathway, practices were required to enter all RA patients insured by the payer into Pathway Compliance Software, utilize oral DMARDs for at least 3 months prior to use of a biologic agent, prescribe the biologic agent at the lowest approved dose and increase dose according to the package guidelines.  Patients were not required to change biologics for ongoing disease activity, but biologics could not be initiated, switched or increased if the patient was in CDAI remission.  Practices achieving 80% compliance with the program were offered increased reimbursement to offset the cost of data collection and program compliance.

Results: From 1/1/12 to 12/31/2013, 3,200 patients were enrolled in the pathway and had at least 2 physician encounters. Of these patients, 586 patients started a new biologic(s) in the study period: 137 started their first biologic and 449 switched to another biologic(s), 301 patients were evaluated based on availability of follow up CDAI scores.  Mean CDAI scores at the visits during which biologic therapy was initiated or changed was 13.1 and 12.2 respectively.  Mean CDAI scores for each of the groups in 3 months since biologic initiation or switch were 10.4 and 11.3 respectively and improved by 27% in biologic naïve group and 7% in biologic switch group. Of the total 4,048 visits with CDAI scores, 587 visits were associated with high CDAI scores, 333 of them (57%) resulted in therapy modification. In patient visits with CDAI scores showing high disease activity (CDAI>22), but without change in therapy to a first time biologic or a second biologic, mean CDAI, PGA (Patient’s Global Disease Activity), EGA (Evaluator’s Global Disease Activity), SJC (swollen joint count) and TJC (tender joint count) scores were 34.7, 6.0, 5.2, 7.5, and 15.3 compared to patients who switched at high disease activity with the mean CDAI, PGA, PhGA, SJC, and TJC of 36.8, 5.5, 5.4, 9.3, 15.8 respectively (p>.05). 

Conclusion: Starting biologic therapy positively impacts clinical outcomes as measured by CDAI score; however CDAI scores do not seem to always impact the decision to start or switch the biologic.  More research is needed to fully elucidate the decision drivers having the highest impact on the decision to switch therapy.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/influence-of-cdai-measurement-on-the-decision-of-community-rheumatologists-to-initiate-or-change-biologic-treatment/