The Epidemiology of Psoriatic Arthritis

Abstract

Psoriatic arthritis (PsA) is a chronic systemic inflammatory disorder characterized by joint and entheseal inflammation with a prevalence of 0.05% to 0.25% of the population and 6% to 41% of patients with psoriasis. PsA is a highly heterogeneous inflammatory arthritis. In this review, current knowledge is discussed regarding the epidemiology of PsA, including disease manifestations, classification criteria for adult and juvenile PsA, methods for recognizing early PsA, including use of screening tools and knowledge of risk factors for PsA, and medical comorbidities associated with PsA.

Keywords: Classification criteria; Comorbidity; Epidemiology; Juvenile psoriatic arthritis; Psoriatic arthritis; Risk factors; Screening tools.

Figure 1. Variability of Disease Characteristics by Study

The prevalence of oligoarthritis, polyarthritis, axial disease, dactylitis and nail disease in a handful of studies is shown above. These manifestations of psoriatic arthritis, the definitions of the manifestations, and the populations included vary considerably by study. For example, Gladman, Lindqvist and Love present data for patients at the first visit whereas Wilson and Reich report data at incident diagnosis. Lindqvist represents a population of patients with early disease (<2 years duration). Axial disease particularly defined quite differently by study. Lindqvist used the original Moll and Wright subgroups to classify patients. Therefore, in that particular study, axial disease as represented here only refers to patients without peripheral arthritis (those patients are classified as oligo- or polyarthritis). In Love et al., axial disease represents patients with inflammatory back pain.