ATLANTA — Potential pathophysiological causes for psoriasis, psoriatic arthritis (PsA), ankylosing spondylitis (AS), and rheumatoid arthritis (RA) are related and display several commonalities across all four disorders, according to research findings presented at the 2019 Annual Meeting of the American College of Rheumatology / Association of Rheumatology Professionals (ACR / ARP), held from 8 to 13 November 2019 in Atlanta, Georgia.
Researchers conducted a series of case-control studies comparing the intensity of selected potential risk factors associated with psoriasis, PsA, AS, and RA growth. Studies were conducted in the UK’s The Health Improvement Network, a database for general practitioners, and included data from 1994 to 2015. Patients with at least 1 code for any of the four conditions matched up to 10 stable general population controls based on age, gender, training, and clinical year.
At diagnosis, median ages for PsA, AS, psoriasis, and RA are 48.3 years (interquartile range [ IQR ], 38-59 years), 40.7 years (IQR, 31-54 years), 43.1 years (IQR, 31-54 years), and 59.9 years (IQR, 48-71 years). While sex in psoriasis was balanced, there were more women with RA and more men with AS (68% and 70% respectively). Overall, the median follow-up period ranged from 6.4 to 7.2 years and among healthy controls was slightly longer.
Univariate quantitative results indicated that PsA risk factors, including obesity, uveitis, and injury, have been repeated previously identified. Smoking has been identified as a risk factor for RA, in line with previous research. In all four diseases, several similar risk factors have been established, including a positive association between pharyngitis, irritable bowel disease, and uveitis, and a similarly strong protective effect on statins. PSA was associated with skin-based risk factors, including skin infections and trauma; joint trauma was also associated with PsA, and both PsA were associated with diarrheal infections.
Many risk factors retained statistical significance in the multivariate models, although the final models varied marginally by gender.