1411: Defining Minimal Disease Activity (MDA) in Psoriatic Arthritis (PsA) with the inclusion of Psoriatic Arthritis Impact of Disease (PsAID) scores rather than Health Assessment Questionnaire (HAQ)

Background/Purpose: Treat to target management is recommended in psoriatic arthritis (PsA) to improve disease control and patient quality of life. Minimal disease activity (MDA) criteria for PsA are a recommended target for treatment. However, the criteria include the health assessment questionnaire (HAQ) which may not always align or be responsive to changes in disease activity or accurately represent disease activity in older patients.

We aimed to test if the new PsA impact of disease (PsAID) score categories of remission and low impact can be used as an alternative item within the MDA criteria and whether this may better reflect patient opinion of disease remission/ Low disease activity (REM/LDA) than the HAQ.

Methods: A post-hoc analysis of data from the Remission/Flare in PsA (ReFlaP) study utilised real world data from adults with PsA for >2 years (NCT03119805). Data included HAQ, PSAID, and patient self-assessment of REM/LDA at clinic visits in 14 countries between 2017-2019. Patients with missing MDA/PsAID/REM data were excluded.

Patients were classified as meeting MDA (5/7 items) and very low disease activity (VLDA; 7/7 items) using either HAQ< 0.5 or PsAID thresholds. PsAID12 was categorised as REM < 1.7; Low impact 1.7-3.1; Moderate impact >3.1-4.8; high impact >4.8. Analysis included summary statistics and chi-squared analysis for categorical variables (p for significance < 0.01) and was performed in SPSS v 30.0.

Results: A total of 308 (164 M, 144 F) patients were included in the analysis (median age 53, IQR 43, 61). 171 were receiving biologic medication and 186 conventional DMARDs. At the baseline visit 234 (131M, 103F) patients reported that they felt that they were in REM/LDA. At baseline, using PSAID12 cut-offs, 126 were in remission and 65 in low impact. 94.4% of those in PsAID remission and 80.0% of those in low impact self-reported that they identified that they were in REM/LDA (figure 1).

There was a significant correlation at both visits between PSAID12 and HAQ scores and good agreement between MDA using HAQ as an item and MDA using PsAID as an item (89.0% for PsAID-rem and 91.0 for PsAID-low). Using the standard MDA-HAQ as a reference, MDA-PsAIDrem and MDA-PsAIDlow had sensitivity 82.6% and 90.7% and specificity was 97.1% and 91.2%.

Using patient reported REM/LDA as a gold standard, sensitivity, specificity, positive and negative predictive values were calculated for all the patients and separately for those over 65 years of age (table 1).

Conclusion: Patient perspective on disease severity is an important variable which is challenging to quantify. Using PsAID remission/low impact (≤3.1) instead of HAQ≤0.5 within the MDA showed very good agreement with a standard MDA assessment. The different MDA definitions showed similar agreement with patient opinion of REM/LDA in the full population.

We propose that PSAID12 category of remission/LDA (< 3.1) could be used as an alternative to HAQ< 0.5 in the MDA criteria and may correlate slightly better with patient opinion in those over 65 years old.