Eder L, Widdifield J, Rosen CF, et al. - This study was attempted to evaluate the accuracy of case definition algorithms for psoriasis and psoriatic arthritis (PsA) in health administrative data and used primary care electronic medical records (EMR) to describe disease and treatment characteristics of these patients. From the Electronic Medical Record Primary Care database, researchers randomly sampled 30,424 adult Ontario residents and distinguished 2,215 patients with any possible psoriatic disease-related terms in their EMR. For psoriasis and PsA, the accuracy of case definition algorithms varies widely. Nevertheless, selected algorithms produced population prevalence estimates that were within the expected ranges, implying that they may be beneficial for further study purposes.