Background/Purpose:   Prior studies have shown an inconsistent relationship between skin and joint symptoms in patients with comorbid PsO and PsA^1-3.  The objective of the study is to characterize the relationship between skin severity and joint activity in patients with comorbid PsA and PsO at enrollment.

Methods: Enrollment visit data from Corrona PsA/SpA registry were obtained from 3/21/2013-9/30/2016. To be included in the analysis, patients had to have a diagnosis of PsA and a history of PsO. PsA patients were evaluated for skin severity as defined by Body Surface Area (BSA) and joint activity as defined by the level of CDAI. Patient characteristics, including current and prior PsA medication use, were obtained during the enrollment visit. We evaluated the relationship of skin severity and joint activity with linear regression. Factors that modify the relationship between BSA and CDAI were separately evaluated using the likelihood ratio test.

Results: 1,542 patients met inclusion criteria. Most were female 816 (52.9%), mean (SD) age was 53.7 (13.2) years, median duration with PsA disease 9.0 years and with PsO disease 18.0 years, and 71 (4.6%) had fibromyalgia. Of the 1484 patients with known DMARD therapy, 266 (18%) patients were on no DMARD therapy, 430 (29%) were on csDMARDs only, 616 (42%) were on first line biologic/tsDMARD therapy, and 172 (12%) were on second line biologic/tsDMARD therapy. The correlation between the skin severity and joint activity was positive and statistically significant 0.183 (p<0.0001). (Figure 1). The relationship between skin severity and joint activity was stronger in patients of younger age, on current treatment of DMARDs and TNFs, with history of MTX use, a higher dactylitis count, not achieving MDA, working from home or being a student, and with higher scores of HAQ, patient reported pain, and fatigue.

Conclusion: Skin severity is directly and significantly related to joint activity. The relationship is modified by age, gender, current therapy, work status, MDA, HAQ, patient reported pain and fatigue. The findings underscore the importance of treating both skin and joint among patients with both PsO and PsA.

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2. Jones SM, Armas JB, Cohen MG, Lovell CR, Evison G, McHugh NJ: Psoriatic arthritis: outcome of disease subsets and relationship of joint disease to nail and skin disease. Br J Rheumatol 1994;33:834–839.

3. Cohen MR, Reda DJ, Clegg DO: Baseline relationships between psoriasis and psoriatic arthritis: analysis of 221 patients with active psoriatic arthritis. Department of Veterans Affairs Cooperative Study Group on Seronegative Spondyloarthropathies. J Rheumatol 1999;26:1752–1756.