Synovitis, as demonstrated in swollen joint count (SJC), has become more widely recognized as a key player in the joint destruction associated with rheumatoid arthritis (RA), and rheumatologists are increasingly using SJC rather than other variables in deciding to change a patient's regimen of disease-modifying antirheumatic drugs (DMARDs), Martin Soubrier, MD, and colleagues report in the Journal of Rheumatology.1

Clinicians were most likely to change DMARD regimens when the patient had seven or more swollen joints, morning stiffness lasting more than an hour, or C-reactive protein (CRP) levels above 17.6 mg/L.
Working with Maxime Dougados, MD, at Hôpital G. Montpied in Clermone-Ferrand, France, and at Hôpital Cochin in Paris, Dr. Soubrier and associates examined factors triggering a change in therapy in a prospective study that included 204 consecutive RA patients.

"The aim of our study was to determine which variables best predict a change in RA therapy in daily clinical practice," the authors write. They found that clinicians were most likely to change DMARD regimens when the patient had seven or more swollen joints, morning stiffness lasting more than an hour, or C-reactive protein (CRP) levels above 17.6 mg/L. The greater importance given to synovitis may be due to increasing knowledge of an association between the presence of synovitis and structural damage, the researchers note. They point out that morning stiffness is the clinical manifestation of persistent inflammation.

"Our findings should be evaluated in other sets of patients and, if confirmed, should prompt reappraisal of current recommendations for initiating anticytokine therapy both in clinical trials and in daily practice," conclude the study authors, led by Dr. Soubrier, a rheumatologist at Hôpital G. Montpied.

Clinical status variables weighed

To determine which clinical status variables best predict a change in DMARD therapy among RA patients, rheumatologists recorded patient characteristics, treatments, and such disease activity data as tender and swollen joint count (28), morning stiffness, visual analog scale (VAS) for pain (0–100 mm), patient global assessment and physician global assessment, Westergren erythrocyte sedimentation rate (ESR), and CRP.

The rheumatologists decided whether or not to initiate or change treatment, but they were not informed that their decisions were part of the investigation. Researchers used logistic regression analysis to evaluate which study variables best predict change in therapy. ROC analysis was used to obtain the cutoff value of the different composite indices including disease activity score 28 (DAS28[ESR]), DAS28(CRP), and the Simplified Disease Activity Index (SDAI) for treatment change as well as sensitivity and specificity.

Composite index values that were associated with a decision to modify DMARD therapy included DAS28(ESR) 4.2 (sensitivity 87%, specificity 70%); DAS28(CRP) 3.6 (sensitivity 86%, specificity 78%); and SDAI 15 (sensitivity 90%, specificity 86%). The discriminative ability of SDAI was better than that of DAS28(CRP) or DAS28(ESR), the study found.

This may be because in the SDAI, a similar weight is given to swollen and tender joint counts, the study authors conclude.

CRP vs ESR

As to why CRP seemed more critical than ESR, the researchers suggest that suppression of CRP is associated with a decrease in radiographic progression and improvement in functional score, while ESR can be influenced by confounding factors such as age, gender, fibrinogen levels, hyperglobulinemia, rheumatoid factor, and anemia. "The desirability of a low CRP explains why the DAS28(CRP) cutoff value was lower than that of the DAS28(ESR)," the researchers write.

Patient preference counts, too

Vibeke Strand, MD, biopharmaceutical consultant and adjunct clinical professor in the division of immunology at Stanford University School of Medicine in Palo Alto, California, and a member of the CIAOMed editorial board, said that patient assessment is also an important factor in the decision to change DMARD therapy or stay the course in RA.

"Ask the patient," she stressed. "It's important to look at swollen joint count or another measure of progression—whether ESR rate, CRP, or imaging studies—but we really have to listen to what the patient is telling us," she said.

Reference

  1. Soubrier M, Zerlak D, Gossec L, et al. Which variables best predict change in rheumatoid arthritis therapy in daily clinical practice? J Rheumatol. 2006 Apr 15; [Epub ahead of print]