Prevalence and clinical features of psoriatic arthritis in psoriasis patients in Spain. Limitations of PASE as a screening tool

Background: Diagnosing and initiating treatment of psoriatric arthritis (PsA) as early as possible is essential to prevent irreversible joint destruction and poor clinical outcomes. Dermatologists are uniquely placed to identify early symptoms of PsA in psoriasis patients but levels of under- and late-diagnosis remain high. Objective: To evaluate the prevalence and clinical features of PsA in Spanish psoriatic patients attended by dermatologists and then referred to rheumatologic units for PsA diagnosis confirmation. Methods: a multicenter, non-interventional, cross-sectional trial conducted at 40 hospitals in Spain. Patients were initially screened for PsA by a dermatologist based on clinical evaluation and results from the Psoriatic Arthritis Screening and Evaluation (PASE) Questionnaire. All patients were then evaluated by a blinded rheumatologist for the presence of PsA using Moll and Wright criteria and Classification Criteria for Psoriatic Arthritis (CASPAR). Results: Of 375 psoriatic patients enrolled at dermatology units, 28.6% patients scored >= 44 in PASE, whereas 32.3% patients screened positive for suspicion of PsA (clinical evaluation and/or PASE). Correlation of suspicion of PsA by dermatologists and PASE score was 0.368 (Pearson correlation coefficient). Following rheumatologic assessment, prevalence of PsA was 22.9% (86/375 patients) according to Moll and Wright and CASPAR criteria. The correlation of diagnosis of PsA between dermatologists and rheumatologists was 0.410 (Kappa Index). Conclusions: Prevalence of PsA in our study was within the range reported in other studies. Our analyses found only a moderate correlation in the diagnosis of PsA between dermatologists and rheumatologists. The screening questionnaire, PASE, showed a moderate predictive value for the diagnosis of PsA.