Psoriatic arthritis, axial spondyloarthritis and rheumatoid arthritis in Norway: nationwide prevalence and use of biologic agents.

In Norway, the combined prevalence of PsA, axSpA, and RA was over 1.5%. Reflecting the good overall access to highly effective but costly biologic treatments, more than a fourth of these patients used biologic agents, which corresponds to over 0.4% of Norwegian adult population.