Good clinimetric alignment between remission and a low impact of disease in patients with axial psoriatic arthritis.

The concept of axial disease in psoriatic arthritis (PsA) is not well established. It is also unclear how this disease domain should be evaluated. We aimed to test whether the remission is aligned with a low impact state of the disease in patients with axial PsA. Post hoc analysis of a multicentre study conducted in 223 patients with PsA under treatment with systemic biological and non-biological therapies. To define axial disease, ASAS criteria were used. Remission corresponded to a BASDAI less than or equal to 2. The impact of the disease was evaluated according to the PsAID. The Cohen's kappa agreement between remission and patient-acceptable symptoms state (PASS) was analysed. Thirty-seven of the 223 patients (16.6%) met ASAS criteria for axial disease. Fifteen of the 122 (12.3%) patients in PASS situation had axial disease compared to 22 of 101 (21.8%) who did not reach this state, p<0.05. All items, as well as the total score of the BASDAI (4.48±2.03 vs. 1.14±1.02) were significantly higher in the patients who did not achieve a PASS, p<0.001. The kappa agreement between BASDAI remission and PASS was high [κ: 0.73 (95%CI: 0.64-0.83) p<0.0001]. BASDAI remission and a low impact of the disease show good clinimetric alignment. Both measures could be useful for a more comprehensive assessment of axial disease in PsA.