Structural entheseal lesions and reduced bone mineral density detected using high-resolution CT imaging of a pair of knuckle joints in patients with psoriasis strongly linked with subsequent development of psoriatic arthritis (PsA) in a single-center study with 114 patients followed for an average of 2.3 years.
Dr. David Simon
“These findings substantiate the concept of mechano-inflammation in the pathogenesis of psoriatic disease,” and suggest that interventions with high efficacy for controlling entheseal inflammation may be a “particularly valuable strategy in interfering with the onset of PsA in patients with psoriatic disease,” David Simon, MD, said at the annual European Congress of Rheumatology, held online this year due to COVID-19.
The study, which is now published in Arthritis & Rheumatology, began with 377 patients with psoriasis who had been referred to the University Hospital in Erlangen, Germany, during 2011-2018, and who tested positive on the German Psoriasis Arthritis Diagnostic questionnaire. The researchers excluded patients with existing signs of PsA, any arthritis or enthesitis or other signs of inflammatory rheumatic disease, and they also excluded patients who had not undergoing a high-resolution peripheral quantitative CT (HR-pQCT) examination of the second and third metacarpal joints of the patient’s nondominant hand, which left 114 patients for their analysis. During a mean follow-up of 28 months, 24 patients (27%) developed PsA. The study patients were an average age of 45 years, and they had been diagnosed with psoriasis for an average of about 16 years.
Dr. Simon and associates used the baseline HR-pQCT scans to make two assessments of each patient: the presence of structural entheseal lesions (SEL) in the two metacarpal joints and the calculated volumetric bone mineral density (vBMD). Their analysis showed that the number and severity of SEL were increased among patients who later developed PsA. In a multivariable model that adjusted for age, sex, body mass index, duration of psoriasis, and arthralgia, patients with any SEL had a fivefold higher rate of developing PsA, compared with patients with no SEL, reported Dr. Simon, a rheumatologist at Erlangen University Hospital.
The analysis of vBMD also showed a strong link between bone density at the entheseal sites of the two studied joints and subsequent PsA development. For every standard deviation increase in vBMD at these sites the subsequent rate of PsA incidence fell by about 67% in an analysis that controlled for the same covariants as well as presence of SEL. The same relationship between higher vBMD and a lower risk for PsA held for both total vBMD measurement and for cortical vBMD, but only at the entheseal site. Levels of vBMD at the intra-articular site of the joints had no statistically significant relationship with subsequent PsA development.
The two metrics also appeared to identify additive risks. Nearly 90% of patients with at least one SEL who also had low vBMD at the entheseal site developed PsA during follow-up, compared with about a 50% rate among patients with at least one SEL but high vBMD.
courtesy EULAR
Dr. Iain McInnes
The imaging method used to run these analyses, HR-pQCT, remains for the time being a “research technique” that “is not generalizable for routine practice,” but further development of this method or of a surrogate measure might make it feasible for future widespread practice, commented Iain McInnes, MD, PhD, president of the European League Against Rheumatism and professor of rheumatology and director of the Institute of Infection, Immunity, and Inflammation at the University of Glasgow.
“We’ve thought for many years that psoriasis and psoriatic arthritis are on a spectrum, and this work is consistent with the idea that some patients with psoriasis develop tissue involvement at entheses and joints,” Dr. McInnes said in an interview. The higher incidence of PsA seen in patients with adverse SEL and vBMD markers was in an “interesting range” that warrants further study. A next step is to run an intervention study in which patients with these adverse markers would receive an intervention randomized against placebo to see if it improved their outcomes, he suggested. Good candidate agents to study in psoriasis patients who have these adverse markers include drugs that inhibit the action of interleukin-17, drugs that target the p19 cytokine subunit of IL-23, and possibly Janus kinase inhibitor drugs.
Dr. Simon has been a consultant to AbbVie and Eli Lilly, a speaker on behalf of Eli Lilly, Janssen, and Novartis, and has received research funding from Eli Lilly and Novartis. Dr. McInnes has been a consultant to AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Gilead, Janssen, Novartis, Pfizer, and UCB, and he has received research funding from Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, and UCB.
SOURCE: Simon D et al. Ann Rheum Dis. 2020 Jun;79[suppl 1]:33-4, Abstract OP0051.