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.
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.