Psoriatic arthritis activity measured via DAPSA28 ‘highly analogous’ to DAPSA gold standard
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Key takeaways:
- DAPSA28 should be preferred over DAS28-CRP if the gold standard, DAPSA, is unavailable.
- DAPSA28 overlapped significantly with DAPSA in its assessment of response and remission at 6 months.
The 28-joint Disease Activity Index for Psoriatic Arthritis score is superior to the DAS28-CRP score as a measure of disease activity in PsA if the “gold standard” DAPSA 66/68 joint counts are not available, according to data.
The original DAPSA and the DAPSA28 scores shared significant overlap in remission and treatment response status, as well as their predictors, at 6 months, the researchers added.
“The disease activity index for PsA (DAPSA), which includes 66/68 joints, is considered a gold standard outcome measure in monitoring disease activity in PsA,” Louise Linde, PhD, of Rigshospitalet Glostrup, in Denmark, and colleagues wrote in Arthritis Care & Research. “In routine clinical practice, however, 66/68 swollen and tender joint counts are not always performed, and therefore a simplified version of DAPSA based on 28 joint counts (DAPSA28) has been developed and validated in patients with PsA.
“In addition, although originally developed for rheumatoid arthritis, the disease activity score with 28 joint counts, a patient global assessment, and CRP (DAS28-CRP) or erythrocyte sedimentation rate has been used as an outcome measure in randomized controlled trials of PsA,” they added. “Outcome measures based on 28 joint counts, however, do not capture the joint involvement in patients with phenotypic PsA (eg, with arthritis in distal interphalangeal joints or feet) and may therefore be less suitable than DAPSA.”
To find whether DAPSA28 or DAS28-CRP should be preferred when assessing PsA disease activity when DAPSA is unavailable, Linde and colleagues analyzed prospectively collected data from nine European registries with DAPSA, DAPSA28 and DAS28-CRP scores. The study included adults who initiated their first TNF inhibitor treatment between January 1, 2009, and December 31, 2018.
The researchers constructed two separate cohorts to analyze outcomes regarding response — which required complete data on all three scores at 6 months (n = 1,866) — and remission — which required complete data on all three scores at both baseline and 6 months (n = 3,159). In addition, they used logistic regression to identify baseline predictors from multiple imputed data.
At 6 months, the proportions of patients achieving remission and response according to each score were as follows:
- DAPSA remission, 27%; response, 44%
- DAPSA28 remission, 28%; response, 44%
- DAS28-CRP remission, 59%; response, 80%
In both DAPSA and DAPSA28, remission and response were both positively associated with longer disease duration, male sex and higher CRP, while they were negatively linked with older age, higher BMI, patient-reported fatigue, health assessment questionnaire scores and tender and swollen joint counts, according to the researchers. Meanwhile, DAS28-CRP had fewer predictors in common with DAPSA.
“At the group level, DAPSA28 seems to be highly analogous to the gold standard outcome measure DAPSA, notably more so than DAS28-CRP,” Linde and colleagues wrote. “Our findings thus support the use of DAPSA28 over DAS28-CRP when 66/68 joint counts are not available, which was often the case in this real-life setting from nine European registries.”