Few nr-axSpA Patients Reach Low Disease Activity without Anti-TNFs

June 10, 2015

Only 1% to 3% of patients with non-radiographic axial spondyloarthritis achieve remission or low disease activity without TNF-α blockers, but these agents are not yet approved for this use in the US.

Tumor necrosis factor alpha (TNF-α) inhibitors are approved in Europe for treating non-radiographic axial spondyloarthritis (nr-axSpA) but not yet in the US -- and a recent study from Germany shows that few patients with nr-axSpA can achieve remission or low disease activity without the drugs.

The study, which followed more than 300 patients with AS and nr-axSpA not treated with TNF-α blockers, shows that only 1% to 3% in either group reach a “spontaneous” remission over 2 years.

In terms of clinical low disease activity -- BASDAI of <4 or BASDAI <2 -– the study shows around one-third of nr-axSpA and AS patients reached that state over 2 years.

When C-reactive protein is added to the BASDAI, the numbers reaching low disease activity (BASDAI <4, normal CRP) slightly increased among those with nr-axSpA, largely because the burden of inflammation is higher in AS.

The patients, 145 with nr-ax-SpA (42% men) and 158 with AS (70% men), were all around age 36 and part of the observational GErman SPondyloarthritis Inception Cohort (GESPIC).

TNF-α drugs have not yet been approved by the FDA for nr-axSpA because of fears of overtreatment since the disorder is less well-defined than AS. It is thought that spontaneous remissions can occur.

However, the authors say their results show “the risk of overtreatment of nr-axSpA with TNF-blockers is small and not different from AS patients.”

Factoring in elevated CRP, the researchers conclude that 12.4% of nr-axSpA patients and 26.8% of those with AS would have been candidates for TNF-α therapy at baseline because they had active disease -- a BASDAI ≥4 and a CRP > 6 mg/L.

Although some patients were treated with NSAIDs, the doses were not “maximal” –- a pre-requisite for TNF therapy -- so “the percentage of nr-axSpA patients suitable for TNFs in daily clinical practice might come close to the numbers reported,” the authors say.

References:

Poddubnyy D, Haibel H, Braun J, et al. Clinical course over two years in patients with early non-radiographic axial spondyloarthritis and ankylosing spondylitis without anti-tumor necrosis factor α treatment: Results from the GErman SPondyloarthritis Inception Cohort (GESPIC).  Arthritis & Rheumatology.2015. Accepted Article. Online May 27. DOI: 10.1002/art.39225.