Major Finding: At week 52 in the IMPACT study, when all psoriatic arthritis patients were being treated with infliximab, 42% of patients achieved MDA; 96% of those who had achieved MDA had no signs of radiologic progression, vs. 67% of those who did not achieve MDA. In the IMPACT II study, comparing the 40% of patients who were in MDA at week 52 with those who were not showed that 78% and 57% showed no signs of radiologic progression.
Data Source: IMPACT study data for 63 patients with psoriatic arthritis and IMPACT II data for 157 similar patients. Both studies compared infliximab and placebo.
Disclosures: Arthritis Research UK funded the study. Dr. Coates said she has received speaker fees from Centocor/Schering-Plough.
BIRMINGHAM, ENGLAND — Radiologic damage is reduced in patients with psoriatic arthritis that is treated with anti–tumor necrosis factor if they meet new minimal disease activity criteria, according to Dr. Laura C. Coates.
This first, and only, composite measure developed for psoriatic arthritis could potentially be used as an objective target or outcome measure in clinical trials, Dr. Coates said at the meeting.
“Minimal disease activity is a concept that has been defined by the Outcome Measures in Rheumatoid Arthritis Clinical Trials group as a state of disease activity deemed a useful target of treatment by both the patient and physician, given current treatment possibilities and limitations,” explained Dr. Coates of the University of Leeds (England).
Dr. Coates and her associates have recently developed minimal disease activity (MDA) criteria for psoriatic arthritis using data on 40 patients with the disease and the expert opinions of 60 rheumatologists and dermatologists (Ann. Rheum. Dis. 2010;69:48-53).
For a patient to achieve MDA, five of the following seven criteria must be met:
▸ A tender joint count less than or equal to one.
▸ A swollen joint count less than or equal to one.
▸ A Psoriasis Area and Severity Index score less than or equal to 1 or a body surface area less than or equal to 3.
▸ A patient pain visual analog score (VAS) less than or equal to 15.
▸ A patient global activity VAS less than or equal to 20.
▸ A Heath Assessment Questionnaire score less than or equal to 0.5.
▸ A tender entheseal points count less than one.
Prior studies have shown that one-third of Canadian patients with psoriatic arthritis can consistently meet the new MDA criteria for more than 1 year, and that when they do, there is a lower rate of joint damage assessed using a clinical scoring system.
Dr. Coates presented the findings of a study that is now looking at the effects of achieving MDA on radiologic outcomes. Data on 220 patients in the IMPACT [Infliximab Multinational Psoriatic Arthritis Clinical Trial] and IMPACT II trials of infliximab therapy vs. placebo were used. Patients in these trials had active psoriatic arthritis and had failed treatment with at least one disease-modifying antirheumatic drug or NSAID. Radiologic progression in the hands and feet was found to be significantly less in patients who achieved MDA with infliximab therapy.
Looking at the data from the original IMPACT trial (n = 63), investigators found that 48% of patients treated with infliximab achieved MDA, compared with 3% of placebo patients (P less than .0001). At week 52, by which time all patients were being treated with the anti-TNF agent, 42% of patients achieved MDA, the majority (96%) of whom had no signs of radiologic progression, compared with two-thirds (67%) of those who did not achieve MDA (P = .012). After 104 weeks of follow-up, 30% were in MDA. None of those who achieved MDA had signs of radiologic progression, compared with 58% of those who did not achieve MDA.
In IMPACT II (n =157), 52% of infliximab patients and 21% of placebo patients achieved MDA after 24 weeks of study (P = .001). At 1 year, when all patients were receiving infliximab, 40% of patients were in MDA. Again, comparing the patients who were in MDA at week 52 with those who were not showed that 78% and 57% showed no signs of radiologic progression (P = .009).
“Around 40%-50% of patients with psoriatic arthritis can achieve MDA” with anti-TNF therapy, Dr. Coates said. She noted that the placebo response was low and that patients who achieve MDA “are more likely to halt their radiographic progression.”
A limitation of the study was that little radiographic progression occurred in the cohort of patients studied.
“This is the only composite disease activity measure that has been developed for psoriatic arthritis to date,” Dr. Coates said. “It encompasses measures of joint disease, skin disease, entheses, and patient-related outcomes, so it really does cover a wide variety of psoriatic disease.”