Rheumatologist-judged inflammatory back pain (IBP) or the criteria for IBP developed for ankylosing spondylitis may not perform well when ascertaining axial involvement in psoriatic arthritis (PsA), according to a recent study. Using prospectively collected data, researchers investigated the agreement between rheumatologist judgement of IBP and IBP criteria (Calin, Rudwaleit and Assessment of Spondyloarthritis International Society) using the kappa coefficient. They also determined the sensitivity, specificity, and likelihood ratios of the presence of back pain, rheumatologist-judged IBP, and the 3 IBP criteria for detecting axial PsA (AxPsA). Finally, they compared the clinical and genetic markers in patients with PsA with axial radiological changes with and without back pain. 171 patients (52% male, mean age 46.6 years) were identified. They found:
- 96 (56.13%) patients reported chronic back pain.
- 65 (38.01%) had IBP.
- 54 (32%) patients had evidence of radiological change in the spine.
- The agreement between rheumatologist judgement of IBP and IBP criteria was highest for the Calin criteria (0.70).
- Positive likelihood ratio for the presence of radiological axial involvement was highest for Rudwaleit criteria (2.17).
Yap KS, Ye JY, Li S, Gladman DD, Chandran V. Back pain in psoriatic arthritis: Defining prevalence, characteristics and performance of inflammatory back pain criteria in psoriatic arthritis. Ann Rheum Dis. 2018;77:1573-1577. doi:10.1136/annrheumdis-2018-213334.