Comparing DAPSA, DAPSA28 and DAS28-CRP in patients with psoriatic arthritis initiating a first TNF-inhibitor across nine European countries.

Objectives: Since 66/68 joint counts are not always performed in routine care, we aimed to determine which of a. the modified 28‐joint disease activity index for psoriatic arthritis (DAPSA28), or b. 28‐joint disease activity score with C‐reactive protein (DAS28‐CRP) should be preferred for monitoring disease activity in psoriatic arthritis (PsA), when the original DAPSA (66/68 joints) is not available.

Methods: Prospectively collected real‐world data of European bio‐naïve PsA patients initiating a first tumor necrosis factor inhibitor (TNFi) were pooled. Remission and response status were evaluated at 6 months by: remission; DAPSA≤4, DAPSA28≤4, DAS28‐CRP<2.6, response; 75% improvement for DAPSA and DAPSA28, and combined EULAR good/moderate responses for DAS28‐CRP. Logistic regression analyses on multiple imputed data were used to identify baseline predictors.

Results: Remission and response cohorts included 3,159 and 1,866 patients, respectively. Six‐month proportions achieving remission/response were: DAPSA: 27%/44%, DAPSA28: 28%/44% and DAS28‐CRP: 59%/80%. Of 14 possible baseline predictors, 11 predicted both DAPSA and DAPSA28 remission, (eight of which also predicted their response, indicated by*): longer disease duration*, male sex* and higher CRP* were positive, while older age*, higher body mass index*, patient fatigue* and global, physician global, health assessment questionnaire score*, tender and swollen* joint counts were negative predictors. Eight and five of these predicted DAS28‐CRP remission and response, respectively.

Conclusion: In patients with PsA, DAPSA28 should be preferred over DAS28‐CRP as a substitute for DAPSA when 66/68 joint counts are not available, due to the large overlap in remission and response status and in predictors between DAPSA and DAPSA28.