Prevalence and Clinical Predictors of Psoriatic Arthritis in Saudi Patients With Psoriasis: A Single-Center Retrospective Cohort Study

BackgroundAmong psoriatic patients, psoriatic arthritis is the most common and most impactful comorbidity. In most cases, it occurs after the onset of psoriasis. Detecting and treating it early is crucial for rheumatologists and dermatologists.ObjectivesThe study aimed to determine the prevalence of psoriatic arthritis among recognized cases of psoriasis, as well as to determine the clinical features of psoriasis that are linked to a greater prevalence of psoriatic arthritis at King Abdulaziz Medical City (KAMC), Riyadh. MethodsA retrospective cohort study of 487 psoriatic patients diagnosed between 2015 and 2023 was conducted at KAMC, Riyadh. The study included subjects aged 18 years or older with a psoriasis diagnosis documented by a dermatologist and a psoriatic arthritis diagnosis documented by a rheumatologist based on the Classification Criteria for Psoriatic Arthritis (CASPAR). Patients younger than 18 years, diagnosed with psoriatic arthritis concurrently with psoriasis, or within 90 days of psoriasis diagnosis, or who lack a documented diagnosis of psoriasis by a dermatologist were excluded. The study evaluated demographic data and medical variables concerning psoriasis (age at onset, type of psoriasis, site of psoriasis, and nail dystrophy) and psoriatic arthritis. SPSS Statistics version 25 (IBM Corp., Armonk, NY) was used to conduct statistical analysis. The p-value of 0.05 was used to evaluate statistical significance.ResultsOverall, 487 patients had psoriasis in this study. Of these, 49 (10%) were diagnosed with psoriatic arthritis. The mean +/- standard deviation of the age of the psoriasis group was 41.7 +/- 15.6 years, with 264 (54.2%) females and 223 (44.8%) males. The clinical features of psoriasis that were linked to a greater frequency of psoriatic arthritis in our study included female gender (71.4%), plaque psoriasis (95.9%), psoriatic lesions involving the extremities (75%), scalp (42.9%), and trunk (36.7%), nail dystrophy (28.6%), as well as the involvement of three or more sites (40.8%) at the time of their initial diagnosis of psoriasis.ConclusionOur study indicated that 10% of Saudi patients with psoriasis had psoriatic arthritis. Moreover, the present study shows that patients with greater psoriatic lesions at initial presentation are more likely to develop psoriatic arthritis.