Background/Purpose: DAPSA is a composite index to assess disease activity in patients with Psoriatic Arthritis (PsA) which includes joint count 66/68, pain and patient´s global assessment (PtGA) and CRP. Since ESR is a more accessible acute phase reactant (APR), our aim was to develop a version of DAPSA using ESR instead of CRP and to estimate its cut-off values.

Methods: Patients with PsA according to CASPAR criteria ≥ 18 years old were included. Sociodemographic data, presence of comorbidities and current treatment were recorded. Morning stiffness, pain, PtGA, physician´s global assessment (PGA) and fatigue were evaluated by Visual Numerical Scale (VNS). Joint count (66/68), presence of dactylitis and enthesitis by MASES. Psoriasis was assessed by PASI and axial mobility by BASMI. APR (ESR in mm/h and CRP in mg/dl) were consigned. Self-questionnaires were performed to assess, quality of life (PsAQoL, ASQoL), functional capacity (HAQ-A and BASFI), and disease activity (BASDAI). Three different DAPSA versions were calculated: DAPSA-CRP, DAPSA-ESR. We also evaluated DAS28, CDAI, SDAI, and CPDAI, and minimal disease activity (MDA). Statistical analysis: Student’s T test and ANOVA. Chi² test, Fisher exact test. Spearman test. Multiple linear regression model. ROC curves with AUC.

Results: A total of 119 patients were included, 62 were males (52.1%), with a median age of 54 years (IQR: 42-63) and a median disease duration of 8 years (IQR: 3-15). 58 (48.7%) of the patients presented mixed involvement, 57 (49.6%) peripheral joint involvement and 2 (1.7%) axial involvement. Median DAPSA-CRP was 12 (IQR: 7-19), median DAPSA-ESR was 14.2 (IQR: 8.2-21.1). DAPSA-ESR showed a very good correlation with: DAPSA-CRP (Rho: 0.97), SDAI (Rho: 0.9), CDAI (Rho: 0.92), DAS28 (Rho: 0.91) and CPDAI (Rho: 0.69); number of swollen joints (Rho: 0.73), morning stiffness (Rho: 0.64), PtGA (Rho: 0, 83) and PGA (Rho 0.63), pain (Rho: 0.77), nocturnal pain (Rho: 0.74), BASDAI (Rho: 0.70), HAQ-A (Rho: 0.65), BASFI (Rho: 0.63), PsAQoL (Rho: 0.56) and ASQoL (Rho: 0.49). In the multiple linear regression, all the components of DAPSA influenced significantly on DAPSA-ESR. DAPSA-ESR cut-off values were extrapolated from DAPSA-CRP´s because they showed the best balance between sensitivity/specificity. The following cutoff values were obtained, sensitivity (Se) and specificity (Sp): remission ≤6.75 (AUC 0.88, Se 80%, Sp 100%), low disease activity from 6.76 to 15.5 (AUC 0.99, Se 100%, Sp 96%), moderate disease activity from 15.6 to 30.7 (AUC 0.99, Se 100%, Sp 96%) and high disease activity ≥30.8 (AUC 0.98, Se 100%, Sp 95.7%).

Conclusion: DAPSA-ESR is a valid alternative index to measure peripheral joint activity in patients with PsA, in those places where the CRP can mean a higher additional cost. We determined its cut-off values, which should be validated in other cohorts.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/disease-activity-in-psoriatic-arthritis-esr-index-maybe-a-valid-tool-to-evaluate-disease-activity-in-patients-with-psoriatic-arthritis-when-crp-is-not-available/