Inflammatory back pain criteria perform well in subset of patients with active axial psoriatic arthritis but not among patients with established axial disease

Psoriatic arthritis (PsA) is a progressive, potentially destructive and disabling immune-mediated inflammatory joint disease and is characterised by involvement of both the appendicular and axial skeleton. Inflammatory spinal disease is one of three inflammatory musculoskeletal (MSK) manifestations that frequently occur in PsA. The reported prevalence of axial disease in patients with PsA is quite variable, and has been reported to be as high as up to 78%.1 Axial involvement is typically characterised by chronic lower back pain, and a significant proportion of such patients develop disabilities due to spinal inflammation. The early identification of patients with axial involvement among patients with psoriasis (PsO) therefore assumes considerable importance. There are limited data about the utility of inflammatory back pain (IBP) criteria among patients with axial PsA (AxPsA). Previous studies have described low sensitivity of IBP criteria among AxPsA (around 68%).2 We read with interest the article of Yap et al , where authors report that IBP criteria may not perform well for axial involvement in PsA.3 The authors also report the low sensitivity and high specificity of IBP criteria among AxPsA. We also aimed to assess the diagnostic performance of back pain features among a much larger cohort of patients with PsA. We have previously reported clinical and genetic association of sacroiliitis (SI) among 283 patients with PsA.4 …