Choy T, Bykerk VP, Boire G, et al., on behalf of CATCH Investigators. Physician global assessment at 3 months is strongly predictive of remission at 12 months in early rheumatoid arthritis: results from the CATCH cohort. Rheumatology (Oxford Journals). Published online ahead of print November 15, 2013.
A low Physicians Global Assessment (PGA) of disease activity after 12 weeks of treatment for early rheumatoid arthritis (RA) can be a good predictor of remission at a year, say Canadian researchers.
Although the DAS28 is used widely to define treatment response and remission, the physician-measured PGA is less likely to be affected by comorbidities.
It also helps differentiate among patients who have similar numbers of affected joints but differing severities, according to the authors.
The multi-site observational prospective study of 1,150 patients in the Canadian Early Arthritis Cohort cohort found that although a number of factors were predictive of 1-year remission, the most statistically significant is a low PGA (mean score of 2.78) at 3 months.
Among the cohort of mostly female patients with a mean age of 53.4 and 6.2 years of disease duration, 562 had complete 1-year data for four remission outcomes:
• 28-joint DAS (DAS28) <2.6 (n=231)
• Clinical Disease Activity Index ≤2.8 (n=83)
• Simple Disease Activity Index ≤3.3 (n=75)
• Boolean-based ACR/European League Against Rheumatism (EULAR) clinical
trial definition of remission (n=69)
The investigators pointed out that the “Boolean-based ACR/EULAR variant is much more stringent than other definitions and gives a lower remission rate.”
For patients meeting these criteria, the baseline factors most associated with 1-year remission were older age, female gender, lower income and education, lower tender joint count, lower patient global assessment (PtGA) and Health Assessment Questionnaire scores, and less pain.
However, early RA patients with a low PGA at 3 months (calculated on a 0 to 10 continuous visual analog scale) were most likely to be in remission at a year and to have better outcomes.
For these patients, the mean 1-year PGA was 1.62.
The group explained that PGA information may help in the treatment plan and prognosis of early RA. Patients who still have a high PGA after 3 months of therapy are less likely to gain remission at 1 year. On the other hand, patients who have a very low PGAat 3 months have a high chance of remission at that same timepoint.