Psoriasis seems often underdiagnosed in patient with axial spondyloarthritis

BACKGROUND: Axial spondyloarthritis (axSpA) is known to be associated with several extra-skeletal manifestations (ESM), including the inflammatory skin disease psoriasis. It is important to recognize and diagnose psoriasis timely in axSpA in order to provide optimal treatment and outcome for both axSpA and psoriasis. METHODS: In this observational study, all patients from the Dutch Groningen Leeuwarden Axial Spondyloarthritis (GLAS) cohort included before June 2016 were sent a questionnaire with self-screening psoriasis questions including prototypical color pictures. RESULTS: Of the 592 questionnaires sent, 448 (75.7%) were eligible for analysis. Of these 448 respondents, 58 (13%) had a positive self-screening for psoriasis symptoms, currently or in the past. In 28 (48%) of 58 patients, psoriasis diagnosis could be verified by medical records, resulting in a psoriasis prevalence rate of 6.3%. In comparison with patients with a confirmed psoriasis diagnosis, patients reporting psoriasis symptoms without a verified diagnosis mentioned more mild than moderate-severe psoriasis symptoms (25% vs. 3%, p = 0.02), and their psoriasis lesions were less often located on the torso area (3% vs. 18%, p = 0.04), the intergluteal cleft (0% vs. 25%, p = 0.02), and legs (7% vs. 43%, p < 0.01). Of the 31 axSpA patients who reported currently active psoriasis, 74% had only mild psoriasis symptoms. CONCLUSIONS: Especially mild psoriasis seems often underdiagnosed in patients with axSpA using a patient questionnaire with prototypical pictures of psoriasis lesions. This questionnaire could be beneficial in tracing patients with undiagnosed psoriasis in daily clinical practice. As a next step, further validation of this questionnaire is needed.