OBJECTIVES: The main objective was to generate a GLobal OMERACT Ultrasound DActylitis Score (GLOUDAS) in psoriatic arthritis and to test its reliability. To this end, we assessed the validity, feasibility and applicability of ultrasound assessment of finger entheses to incorporate them into the scoring system. METHODS: The study consisted of a stepwise process. First, in cadaveric specimens, we identified enthesis sites of the fingers by ultrasound and gross anatomy, and then verified presence of entheseal tissue in histological samples. We then selected the entheses to be incorporated into a dactylitis scoring system through a Delphi consensus process among international experts. Next, we established and defined the ultrasound components of dactylitis and their scoring systems using Delphi methodology. Finally, we tested the interobserver and intraobserver reliability of the consensus- based scoring systemin patients with psoriatic dactylitis. RESULTS: 32 entheses were identified in cadaveric fingers. The presence of entheseal tissues was confirmed in all cadaveric samples. Of these, following the consensus process, 12 entheses were selected for inclusion in GLOUDAS. Ultrasound components of GLOUDAS agreed on through the Delphi process were synovitis, tenosynovitis, enthesitis, subcutaneous tissue inflammation and periextensor tendon inflammation. The scoring system for each component was also agreed on. Interobserver reliability was fair to good (κ 0.39-0.71) and intraobserver reliability good to excellent (κ 0.80-0.88) for dactylitis components. Interobserver and intraobserver agreement for the total B-mode and Doppler mode scores (sum of the scores of the individual abnormalities) were excellent (interobserver intraclass correlation coefficient (ICC) 0.98 for B-mode and 0.99 for Doppler mode; intraobserver ICC 0.98 for both modes). CONCLUSIONS: We have produced a consensus-driven ultrasound dactylitis scoring system that has shown acceptable interobserver reliability and excellent intraobserver reliability. Through anatomical knowledge, small entheses of the fingers were identified and histologically validated.

3rd Rheumatology Department National Institute of Musculoskeletal Diseases Budapest Hungary

Academic Rheumatology Centre Department of Clinical and Biological Sciences Università degli Studi di Torino Turin Italy

Autonomous University of Madrid Madrid Spain

Center for Rheumatology and Spine Diseases Rigshospitalet Copenhagen Denmark

Department of Clinical Medicine Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark

Department of Internal Disease Propaedeutics and Rheumatology Medical University of Plovdiv Clinic of Rheumatology University Hospital Kaspela Plovdiv Bulgaria

Department of Internal Medicine 3 Division of Rheumatology Medical University Vienna Wien Austria

Department of Rheumatology and Joint and Bone Research Unit Hospital Universitario Fundación Jiménez Díaz IIS FJD Autonomous University Madrid Spain

Department of Rheumatology and Joint and Bone Research Unit Hospital Universitario Fundación Jiménez Díaz IIS FJD Madrid Spain

Department of Rheumatology Flevoziekenhuis Almere The Netherlands

Department of Rheumatology Hospital Universitario Ramón y Cajal Madrid Spain

Department of Rheumatology Institute of Rheumatology Prague Czech Republic

Department of Rheumatology Leiden University Medical Centre Leiden The Netherlands

Department of Rheumatology Tallaght University Hospital Dublin Ireland

Department of Rheumatology Università Cattolica del Sacro Cuore Policlinico Universitario Agostino Gemelli IRCSS Rome Italy

Department of Rheumatology Zealand's University Hospital Køge Denmark

Division of Musculoskeletal and Rheumatic Disorders Instituto Nacional de Rehabilitacion Luis Guillermo Ibarra Ibarra Mexico City Mexico

Division of Rheumatology University of Ottawa the Ottawa Hospital Research Institute Ottawa Ontario Canada

Histology Unit Faculty of Medicine and Health Sciences University of Barcelona Barcelona Spain

Human Anatomy and Embryology Unit Department of Pathology and Experimental Therapeutics Faculty of Medicine and Health Sciences University of Barcelona Barcelona Spain

Instituto Poal de Reumatología Barcelona Spain

Intermountain Health Care Inc Salt Lake City Utah USA

Musculoskeletal Radiology Group Medical Imaging Clinic Semmelweis University Budapest Hungary

Postgraduate Program in Health Sciences Rheumatology Ultrasonography Service Pontifical Catholic University of Campinas Sao Paulo Brazil

Reumakliniek Flevoland Lelystad Netherlands

Rheumatology Center St Irina Sofia Bulgaria

Rheumatology Clinic Department of Medicine University of Udine c o Azienda Sanitaria Universitaria Friuli Centrale Udine Italy

Rheumatology Clinical Hospital Sf Maria Bucharest Romania

Rheumatology Department Faculty of Medicine Zagazig University Zagazig Egypt

Rheumatology Department University of Medicine and Pharmacy Craiova Craiova Romania

Rheumatology Division 2nd Rehabilitation Department Spitalul Clinic de Recuperare Cluj Napoca Cluj Napăoca Romania

Rheumatology Unit Department of Clinical and Molecular Sciences Polytechnic University of Marche Jesi Italy

Rheumatology Unit IRCCS Sacro Cuore Don Calabria Negrar Italy

School of Medicine University of Western Australia Perth Western Australia Australia

Tergooi MC Hospital Hilversum and Reumakliniek Lelystad Lelystad Netherlands

University of Florida College of Medicine Jacksonville Florida USA

Virtus Medical Group Hong Kong SAR Hong Kong Hong Kong

References provided by Crossref.org