Supplementary Material for: Spanish Validation of the GEPARD Questionnaire for the Detection of Psoriatic Arthritis in Argentinian Patients with Psoriasis

Background/Objective: Psoriatic arthritis (PsA) is preceded by psoriasis in approximately 80% of cases. Dermatologists are pivotal for early detection. It is important to have simple tools that allow the detection of PsA in patients with skin psoriasis. The aim of our study was to evaluate the performance of an adapted version of the GEPARD Questionnaire in Spanish in Argentinian patients with psoriasis. Methods: This is a cross-sectional study. A new Spanish (Argentinian) (GEPARDa) translated version of the original questionnaire (German) was developed and then tested as a diagnostic tool in patients with psoriasis, PsA, osteoarthritis associated to psoriasis, and osteoarthritis, all evaluated by rheumatologists who used the CASPAR criteria. Results: Eighty-three patients were included (55 [66.3%] women with a mean age of 50.7 years [SD 6.3]). Forty-four patients had PsA (29 [34.9%] patients had previous diagnosis of PsA, and 15 [18%] were newly diagnosed after referral by their dermatologists), and 39 patients were without PsA (18 [21.6%] patients had psoriasis without articular involvement, 6 [7.22%] had psoriasis associated with osteoarthritis, and 15 [18%] had osteoarthritis). An area under the curve of 0.9554 (SD 0.01; 95% CI 0.91–0.99) was calculated considering the CASPAR criteria as the gold standard. With a cutoff of ≥6 the questionnaire showed a sensitivity of 88.64%, a specificity of 89.74%, a positive likelihood ratio of 8.6, and a negative likelihood ratio of 0.12. Conclusions: The GEPARDa version has proven to be a diagnostic tool with excellent performance so that it can be considered a valid tool for the detection of PsA in Argentinian patients.

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