Biologic Treatment in Patients With Axial Spondyloarthritis and Low Disease Activity

A Polish study of axial spondyloarthritis (axSpA) patients who discontinued treatment with anti—tumor necrosis factor (anti-TNF) therapy because of low disease activity (LDA) found that more than half eventually needed to restart anti-TNF therapy.

Changes in the values of C-reactive protein (CRP) level and erythrocyte sedimentation rate (ESR), which were used as disease activity indicators, were correlated with a more stable response to anti-TNF therapy. Patients who resumed anti-TNF treatment had no recurrence of symptoms. The study’s authors, Agata Sebastian, MD, and colleagues, conclude that more study is needed to determine whether and how long anti-TNF treatment should be continued in axSpA patients despite achievement of LDA, and whether the dose of anti-TNF should be reduced to obtain long-term LDA.

The researchers undertook the study, published in the April 2017 issue of Reumatologia, because they said there is presently no formal proof that anti-TNF are in fact disease modifying in axSpA, and it is not clear how long anti-TNF therapy should last and which treatment algorithm to choose when disease activity is low or remission occurs. The authors explain that the Polish National Health Fund program defines active ankylosing spondylitis (AS) as occurring when the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is 4 or greater and LDA as occurring when BASDAI less than 3 persists longer than 6 months. Under the Polish healthcare system rules, anti-TNF therapy can be reinstituted when BASDAI increases to be over 4.

The study followed 65 patients with axSpA who were treated with anti-TNFs (etanercept, 72%; adalimumab, 2%; and infliximab, 3%). The patients were observed from 2009 to 2015 for an average of 9 to 48 months. Prior to anti-TNF treatment, all the patients were treated for 6 months with 2 nonsteroidal anti-inflammatory drugs (NSAIDs), with no clinical effect. Response to therapy was defined as a reduction of 50% or more in BASDAI score, or at least 2 units in visual analogue scale (VAS) for low back pain after 12 weeks of treatment with anti-TNF compared with baseline.

A total of 83% of patients achieved LDA after 9 months of anti-TNF therapy. During follow up, 73% of patients with LDA had an increase in disease activity after a mean of 14 weeks and needed to restart anti-TNF treatment. After treatment was resumed, LDA was regained in all patients after a mean of 7 weeks. Seventeen percent never achieved LDA and 22% had LDA longer than 6 months without relapse. At baseline, higher levels of CRP and ESR were observed in patients with disease relapse at the end of treatment and with LDA shorter than 6 months.

The authors conclude that due to the chronic nature of axSpA, all patients should be given the opportunity to resume anti-TNF treatment because it is the best therapy currently available.