U.S. ankylosing spondylitis prevalence rising
The diagnostic prevalence of axSpA in the United States increased by 86% between 2006 and 2014 in a retrospective analysis based on Medicare fee-for-service claims data. A separate analysis using IBM MarketScan data for the same years was confirmatory, showing a 56% increase, Jeffrey R. Curtis, MD, MS, MPH, of the University of Alabama at Birmingham reported at the 2020 annual meeting of the European League Against Rheumatism (EULAR), now known as the European Alliance of Associations for Rheumatology.
“I think the take home is we’re seeing more of this. Some of this is likely due to increased awareness and inclusion of nonradiographic disease,” according to Dr. Ruderman.
Two previously overlooked comorbidities
It’s well recognized that 5%-10% of patients with axSpA have concurrent inflammatory bowel disease. But how about irritable bowel syndrome (IBS)?
A study of 186 Swedish patients with axSpA in the population-based SPARTAKUS registry, none with inflammatory bowel disease, concluded that 30% of them met ROME III diagnostic criteria for IBS, compared with 16% of healthy controls. Of note, the axSpA patients with comorbid IBS had significantly worse axSpA disease outcomes, compared with those without IBS as measured by pain, fatigue, and quality-of-life scores, as well as significantly greater disease activity on the Bath Ankylosing Spondylitis Disease Activity Index.
New-onset inflammatory back pain occurred in a hefty 24% of 513 Saudi patients placed on isotretinoin for acne. About 42% of those with inflammatory back pain displayed evidence of sacroiliitis on MRI. Moreover, 52% of patients with MRI-proven sacroiliitis fulfilled ASAS criteria for axSpA. In this longitudinal study, the MRI abnormalities and back pain symptoms completely resolved after isotretinoin discontinuation, but it took a long time: up to 9 months.
“When you see these people with inflammatory back pain on isotretinoin, I think it’s important that before you saddle them with a diagnosis that they have axSpA – a diagnosis that will go with them forever – give them time off drug, because this can look like the real thing. It’s something to think about as these pretty young kids come in to see you with back pain: Always ask about their medication history because it could be important,” Dr. Ruderman said.
A successful biologic remission induction-and-maintenance strategy
The phase 3b, multicenter C-OPTIMISE study sought to determine the best strategy for avoiding axSpA flares once sustained clinical remission has been achieved with a TNF inhibitor, in this case certolizumab pegol (Cimzia). The first part of the trial involved 736 patients with early axSpA, including 329 with nonradiographic disease. During the 48-week open-label induction period, 43.9% of patients achieved sustained clinical remission at the approved dose of 200 mg every 2 weeks, with similar success rates in radiographic and nonradiographic axSpA.
Those in sustained remission were then randomized double blind to one of three groups: an additional 48 weeks of certolizumab pegol at the full maintenance dose of 200 mg every 2 weeks, reduced maintenance dosing at 200 mg every 4 weeks, or placebo. During this period, 83.7% of the group who continued on full-dose certolizumab remained flare free, as did 79% of those on the reduced maintenance dose. In contrast, only 20.2% of patients in whom the biologic was completely withdrawn remained flare free. The investigators concluded that certolizumab dose reduction is a winning strategy for maintenance of clinical remission, as it reduces costs and limits long-term exposure to immunosuppressive therapy while maintaining clinical benefits.