{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,29]],"date-time":"2026-03-29T21:26:53Z","timestamp":1774819613985,"version":"3.50.1"},"reference-count":25,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2025,9,23]],"date-time":"2025-09-23T00:00:00Z","timestamp":1758585600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background: Achieving low disease activity or remission in psoriatic arthritis (PsA) remains difficult. The GRAPPA group recently defined difficult-to-treat (D2T) PsA but did not include a time-based criterion. Objectives: This study aimed to evaluate the prevalence and features of D2T PsA using several operational definitions. Methods: A cross-sectional study at a tertiary center enrolled PsA patients with active disease confirmed by clinical exam and ultrasound. D2T PsA was defined by: (1) failure of \u22651 csDMARD plus \u22652 b\/tsDMARDs with different mechanisms of action (GRAPPA definition); (2) \u22652 b\/tsDMARDs with different mechanisms of action within 12 months (time-based definition); or (3) failure of &gt;3 b\/tsDMARDs with different mechanisms of action (very refractory). Clinical, demographic, radiographic, and ultrasound data were analyzed, and multivariable analyses identified independent associations. Results: Seventy-two patients (54.2% female, median age 56, disease duration 84 months) all had active disease (median DAPSA 17); 68% had comorbidities. Enthesitis, dactylitis, and nail disease were seen in 20.8%, 45.8%, and 41.7%. HLA-B27 positivity was 13.9%. Radiographic erosions and ultrasound paratenonitis were present in 37.5% and 33.3%. GRAPPA D2T criteria were met by 23.6%, linked to longer disease duration, higher activity, HLA-B27, comorbidities, and combined therapy. Time-based D2T (12.5%) showed higher DAPSA and nail involvement, with ultrasound paratenonitis and combined therapy independently associated. Very refractory patients (11.1%) only correlated with combined therapy. Conclusions: Up to one-fourth of PsA patients remain active despite multiple treatments. D2T PsA is associated with disease duration, comorbidities, activity, HLA-B27, combined therapies. Remarkably, patients who fulfilled the &lt;12-month D2T definition were more likely to present with nail involvement and ultrasound-detected paratenonitis.<\/jats:p>","DOI":"10.3390\/diagnostics15192418","type":"journal-article","created":{"date-parts":[[2025,9,23]],"date-time":"2025-09-23T10:27:53Z","timestamp":1758623273000},"page":"2418","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Clinical and Ultrasound Characteristics of a Difficult-to-Treat Psoriatic Arthritis Population"],"prefix":"10.3390","volume":"15","author":[{"given":"Georgina","family":"Novell","sequence":"first","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ana Bel\u00e9n","family":"Azuaga","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-3722-9486","authenticated-orcid":false,"given":"Luc\u00eda","family":"Alascio","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Oriana","family":"Oma\u00f1a","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Claudia","family":"Arango","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joshua","family":"Pe\u00f1afiel-Sam","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3068-5752","authenticated-orcid":false,"given":"Andr\u00e9s","family":"Ponce","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8426-7268","authenticated-orcid":false,"given":"Juan Camilo","family":"Sarmiento-Monroy","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5867-8434","authenticated-orcid":false,"given":"Beatriz","family":"Frade-Sosa","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8177-702X","authenticated-orcid":false,"given":"Jos\u00e9 A.","family":"G\u00f3mez-Puerta","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"},{"name":"Faculty of Medicine, University of Barcelona, 08007 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2606-0573","authenticated-orcid":false,"given":"Juan D.","family":"Ca\u00f1ete","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7047-8056","authenticated-orcid":false,"given":"Julio","family":"Ram\u00edrez","sequence":"additional","affiliation":[{"name":"Arthritis Unit, Rheumatology Department, Hospital Cl\u00ednic of Barcelona, 08036 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e003809","DOI":"10.1136\/rmdopen-2023-003809","article-title":"Difficult-to-treat psoriatic arthritis (D2T-PsA): A scoping literature review informing a GRAPPA research project","volume":"10","author":"Singla","year":"2024","journal-title":"RMD Open"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2273","DOI":"10.1016\/S0140-6736(18)30830-4","article-title":"The pathogenesis of psoriatic 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Bone Spine"}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/15\/19\/2418\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:47:38Z","timestamp":1760035658000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/15\/19\/2418"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,9,23]]},"references-count":25,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2025,10]]}},"alternative-id":["diagnostics15192418"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics15192418","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,9,23]]}}}