Is BASDAI a responsive instrument in PsA?

Use of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) as an instrument in psoriatic arthritis (PsA) demonstrates “reasonable” responsiveness but falls short of distinguishing peripheral PsA from axial (ax)PsA, according to a recent study.

At the time of therapy initiation, the mean baseline BASDAI score was 5.0 among patients with axPsA (n=40) and 4.8 among those with peripheral PsA disease (n=79). No significant between-group difference was observed in patient-reported outcome scores.

In addition, the mean change for BASDAI was similar between axial and peripheral disease (‒0.75 vs ‒0.83). Standardized response means were also comparable across axial and peripheral PsA for BASDAI (‒0.37 vs ‒0.44) and the individual BASDAI items.

“BASDAI has reasonable responsiveness in PsA but does not differentiate between axPsA and peripheral PsA,” the investigators said.

For this study, a team of investigators examined individuals with PsA initiating therapy in a longitudinal cohort study in the US. AxPsA was characterized by the fulfilment of the Assessment of Spondyloarthritis International Society axial spondyloarthritis classification criteria or presence of axial disease imaging features.

The investigators descriptively reported baseline BASDAI, individual BASDAI items, patient global assessment, patient pain, and Routine Assessment of Patient Index Data 3, as well as score changes following initiation of therapy. They also calculated the standardized response means as the mean change divided by the standard deviation of the change.