Background/Purpose:  To determine the prevalence of Psoriatic Arthritis (PsA) in a cohort of psoriasis patients according to CASPAR criteria, and compare it with that resulting from the use of ASAS peripheral and axial criteria for SpA and New York criteria for AS.

Methods: The first 100 patients that consecutively attended the Psoriasis clinic of a Dermatology Service were assessed. Demographic and clinical data were collected, and all patients were questioned and examined by a rheumatologist for joint manifestations. In all cases, rheumatoid factor and radiographies of hands, feet, cervical spine and pelvis for sacroiliac joints were obtained. All X-rays were read independently by two observers in blind fashion. Patients with objective joint manifestations, both axial and peripheral, were evaluated for their fulfillment of CASPAR, ASAS peripheral and axial, and New York criteria. Correlations were calculated by Spearman’s test. Categorical variables were compared by x², and continuous variables were compared by Student’s test.  

Results: Of the 100 patients included (62 males) median age was 48 years and median duration of psoriasis 11 years. 93% of patients presented psoriasis vulgaris, and 56% nail involvement. Seventeen patients had peripheral arthritis, mono/ oligoarticular in 9 and polyarticular in 8. Median time of arthritis duration was of 8 years. Seven patients had chronic neck pain while 6 patients had chronic low back pain.13 patients had cervical spine and 6 patients lumbar spine limitation. Among all psoriatic patients, radiographic sacroiliitis grade 2 and 3 was detected in 12, and grade 4 in 2, being symmetric in 7 of the patients. At cervical level, 10 patients presented syndesmophytes and 3 had interapophyseal ankylosis. Of all patients, 17% fulfilled CASPAR and ASAS peripheral criteria, 6% New York and 5% ASAS axial criteria. Patients who met CASPAR criteria showed a significantly higher time of psoriasis duration compared to those without arthritis (m16 vs 10 years p=0.02), and a higher frequency of nail involvement (88.2% vs 49.4% p=0.003). Five patients (29.4%) fulfilled the ASAS axial criteria; all of them presented peripheral involvement: mono/olygoarticular in 3 and polyarticular in 2 patients. Patients with peripheral and axial involvement presented a significantly higher frequency of erythrodermic psoriasis compared to the other patients (35.3% vs 1.2% p=0.0006 and 80% vs 16.7% p=0.02). Among the 95 patients without the ASAS axial criteria, 9 showed sacroiliitis grade 2 or higher. Among the 83 patients without arthritis, only 1 presented peripheral radiological changes, whereas 5 presented sacroiliitis grade 2 or 3.

Conclusion: Prevalence of PsA, for both CASPAR and  ASAS peripheral criteria was of 17%. According to the ASAS criteria, 5% of patients presented axial involvement, while 6% presented axial involvement regarding the New York criteria. All cases with articular involvement presented a higher frequency of psoriasis nail involvement and skin severity. It is worth to note that few patients without signs or symptoms of arthritis had radiological changes, both axial and peripheral, precluding a proper classification.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/prevalence-of-psoriatic-arthritis-in-psoriasis-patients-according-to-newer-classification-criteria/