The impact of concomitant diffuse idiopathic skeletal hyperostosis on the achievement of minimal disease activity in subjects with psoriatic arthritis

Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by ossification of different entheses. Psoriatic arthritis (PsA) is a seronegative spondyloarthritis associated with psoriasis. Given the possible overlap of the two diseases, we assessed whether DISH presence may affect PsA clinical outcomes. Also, predictors of DISH presence in the cohort were investigated. Consecutive PsA patients from two Italian Rheumatology Research Units were enrolled. Subjects were splitted into two groups, according to the current treatment (TNF-α blockers or traditional DMARDs). All patients underwent a rheumatologic examination, blood sample collections and spine radiographs. Information about traditional vascular risk factors was recorded. In each patient, the presence of minimal disease activity was evaluated and the presence of DISH was established according to the Resnick and Niwayama criteria. Among the 80 enrolled subjects (57.5 % men, mean age 56.5 ± 11.1 years), the overall prevalence of DISH was 30.0 %. Patients with DISH were older, with higher BMI and waist circumference. DISH subjects showed worsen BASMI, HAQ and ESR. In a multivariate regression model, BASMI was a significant predictor of DISH presence (OR 3.027, 95 % CI 1.449–6.325, p = 0.003). The prevalence of MDA was lower in DISH patients than in no-DISH (16.7 vs 41.1 %, p = 0.041), and the presence of DISH was a predictor of not achieving MDA (OR 3.485, 95 % CI 1.051–11.550, p = 0.041). PsA subjects with DISH showed worsen indices of spine mobility and articular function and lower prevalence of minimal disease activity than no-DISH patients.