Psoriatic arthritis among Egyptian patients with psoriasis attending the dermatology clinic: prevalence, comorbidities, and clinical predictors

OBJECTIVES: Early diagnosis and treatment of psoriatic arthritis (PsA) help to prevent progressive joint involvement and disabilities. There is a problem in the early diagnosis of PsA worldwide, which may be attributed to the dermatologists missing PsA symptoms and signs and a lack of effective screening tools. AIM OF THE STUDY: The current study was designed to assess the prevalence, comorbidities, and clinical predictors associated with the development of PsA in psoriasis patients. MATERIAL AND METHODS: A cross-sectional observational study was performed. Screening questionnaires – the Psoriasis Epidemiology Screening Tool (PEST) and Early Arthritis for Psoriatic Patients (EARP) – were applied to 200 psoriasis patients; among them n = 22 (11% of all tested patients) were in developmental age. Those with positive questionnaires were classified as having PsA or not according to the classification for psoriatic arthritis criteria. Body surface area, psoriasis area and severity index, and psoriasis disability index tools were used for assessing psoriasis patients. A full rheumatological and dermatological evaluation were carried out for PsA patients. RESULTS: The prevalence of PsA was found to be 30%, with a mean age of 45.48 ±10.79 years. Further, psoriasis preceded the onset of PsA in 46 patients (76.6%), arthritis began before psoriasis in 6 individuals (10%), and both psoriasis and arthritis coincided in 8 (13.3%) patients. Obesity (OR 7.0, 95% CI: 2.61–18.85), nail psoriasis (OR 5.02, 95% CI: 2.02–12.476), and intergluteal cleft site (OR 12.659, 95% CI: 4.302–37.255) were associated with increased risk of PsA. However, classic plaque psoriasis (OR 0.149, 95% CI: 0.051–0.433) and flexure site (OR 0.238, 95% CI: 0.076–0.746) were linked with a decreased risk of PsA development. CONCLUSIONS: Screening for PsA in patients with psoriasis revealed a significant number of undiagnosed cases of PsA that should be treated early. Obesity, nail psoriasis, and psoriasis at the intergluteal sites can help predict the PsA development.