Session Type: Abstract Submissions (ACR)
There are limited data regarding the incidence of PsA in patients with psoriasis. We aimed to estimate the incidence of PsA in a prospective cohort of psoriasis patients and to identify risk factors for the development of PsA in these patients.
The setting is a prospective longitudinal cohort study of psoriasis patients without arthritis at baseline. Patient with a diagnosis of psoriasis confirmed by a dermatologist were enrolled. All patients were evaluated by a rheumatologist at baseline. Exclusion criteria included the presence of inflammatory arthritis or spondylitis in the past or at the time of assessment. All study participants were then reassessed annually by a rheumatologist for signs and symptoms of arthritis. Information was collected about their lifestyle habits, co-morbidities, skin activity and medications. Patients who developed inflammatory arthritis or spondylitis were classified as PsA if they fulfilled the CASPAR criteria. Patients who failed to come to the yearly assessment were requested to fill out the Toronto Psoriatic Arthritis Screen (ToPAS II) questionnaire, a screening questionnaire designed to detect PsA among patients with psoriasis. Subjects scoring ≥8 points on the ToPAS II were classified as suspected PsA. We summarize the results of 7 years of follow up and report the annual incidence of PsA from the onset of psoriasis that was estimated using an event per person-years analysis. Cox proportional hazard model, with time-dependent explanatory variables and date of enrollment as the time of origin, was used to compute the multivariate relative risk (RR) for incident PsA adjusting for sex and age.
The results of the 579 patients who were recruited from January 2006 and followed until December 2013 are summarized. The mean duration of follow up was 3.5±1.9 years per person. A total of 46 patients developed PsA since enrollment and 9 additional patients were considered suspected cases of PsA according to their scoring in ToPAS II. The annual incidence rate of confirmed cases was 3.1 (95% confidence interval (CI) 2.2, 4.0) PsA cases per 100 psoriasis patients. When suspected cases were included in the analysis, the annual incidence rate increased to 3.7 (95% CI 2.7, 4.7) PsA cases per 100 psoriasis patients. The distribution of the time to development of PsA was fit with an exponential model, suggesting a constant hazard rate. The following variables predicted the development of PsA: flexural psoriasis (RR 4.9 p=0.03), nail pitting (RR 2.3 p=0.006), higher modified Nail Psoriasis Severity Index score (RR 2.8 p=0.008) and lower level of education (high school incomplete vs. University RR 3.33, p=0.04). Obesity vs. normal weight predicted the development of PsA when suspected cases of PsA were included in the analysis (RR 2.3 p=0.03)
The incidence of PsA in patients with psoriasis is higher than previously reported. Flexural psoriasis, psoriatic nail lesions, lower level of education and obesity predict the development of PsA in patients with psoriasis.
R. J. Cook,
D. D. Gladman,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-incidence-and-risk-factors-for-psa-in-patients-with-psoriasis-a-prospective-cohort-study/