The presence of swelling in a joint with erosions induced by rheumatoid arthritis seems to interfere with treatment response, according to results from a 1-year follow-up of patients in the Trial of Etanercept and Methotrexate with Radiographic Patient Outcomes (TEMPO) study.
Dr. Désirée van der Heijde, professor of rheumatology at Leiden University Medical Center, the Netherlands, and her associates analyzed the interpretations of radiographs at baseline and after 1 year of follow-up for 12,848 joints from 440 rheumatoid arthritis patients in the methotrexate and methotrexate-plus-etanercept arms of the trial.
The original trial also included an arm of patients who were treated with etanercept alone. But Dr. van der Heijde and her associates did not include those patients in this analysis.
The joints assessed at baseline and followup included the proximal interphalangeal, metacarpophalangeal, and metatarsophalangeal. Each radiograph was examined independently twice each by two readers who were unaware of the treatment status and did not know the order of the radiographs.
Only 249 (2%) of the joints showed signs of repair, which was defined as at least one negative erosion change score among the four follow-up readings for each joint.
Further, all other follow-up readings had to be rated as having no progression of erosion.
In damaged joints, the finding of erosion repair was significantly associated with absent swelling or the finding of improved swelling, Dr. van der Heijde reported at the annual European Congress of Rheumatology.
Of the 116 repaired joints that showed no change in clinical swelling at follow-up, only 8 had swelling present at both baseline and follow-up. Swelling was absent at baseline in the other 108 joints.
Among the 133 joints in which swelling improved from baseline to follow-up, only 15 still had swelling at follow-up. The remaining 118 joints did not show any signs of swelling.
The relationship between repair and swelling for each joint in the study was statistically independent of any correlation between joints within a single patient.
The investigators found the same relationship between repair and swelling when they examined changes in joint-space narrowing rather than changes in erosion.
The results also indicated that the progression of erosion mostly occurs in individual joints with positive erosion change scores and persistent or worsening swelling.
Previous clinical studies have not validated whether traditional radiographic scoring methods of assessing rheumatoid arthritis damage can be applied at the level of a single joint to determine which individual joints are most likely to undergo repair.
Direct evidence of repair of individual joints within a patient can be obtained through sequential biopsies, but this method is impractical, in part because there is a strong possibility of missing individual repaired joints.
Few treated patients have an overall negative erosion change score (which indicates repair) after radiographic assessment of their joints. Only 3%–10% of patients in the TEMPO trial showed radiographic repair.
"The original trial also included an arm of patients who were treated with etanercept alone. But Dr. van der Heijde and her associates did not include those patients in this analysis. "