{
  "abstract": "Background The Leiden group and the Assessment of Spondyloarthritis International Society (ASAS)-MRI study group have proposed definitions for structural (SL) and active (AL) lesions typical for axial spondyloarthritis (axSpA) on MRI of the sacroiliac joints (MRI-SIJ).Objectives To analyse the predictive validity of proposed SL and AL MRI-SIJ definitions in early axSpA and compare proposed AL with the current ASAS-MRI-SIJ+ definition.Methods Patients with chronic back pain (≤2 years) from the Spondyloarthritis Caught Early cohort were diagnosed as axSpA or non-axSpA after 2 years follow-up. Three central readers scored baseline MRI-SIJ for SL (erosions and fat lesions) and AL (bone marrow oedema). Validation required specificity and positive predictive value (PPV) ≥95%.Results Among 643 patients (52% axSpA), SL were infrequent (2%–14%). All Leiden and most MRI study group SL definitions met the validation threshold, except for ‘erosion in ≥2 consecutive slices’ and the overall MRI study group definition (PPV <95%). The ASAS-MRI-SIJ+ definition had a higher sensitivity than the MRI study group AL (40% vs 31%) with similar specificity (98% vs 99%). Combining SL and AL, the Leiden SL with ASAS-MRI-SIJ+ definition met the validation threshold with the highest sensitivity (46%). SL increased sensitivity beyond AL alone by 6%–11%.Conclusions The ASAS-MRI-SIJ+ definition outperforms the MRI study group AL. The Leiden SL combined with the ASAS-MRI-SIJ+ definition is validated, most sensitive and feasible as it simultaneously upholds lesion quantification and detection precision, making it the preferred approach. Nevertheless, SL were uncommon in early axSpA, contributing only marginally beyond AL definitions in early diagnosis.",
  "authors": [
    {
      "affiliations": [
        "Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands"
      ],
      "name": "Liese J E de Bruin"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands",
        "Department of Rheumatology, Coimbra Local Health Unit, Coimbra, Portugal"
      ],
      "name": "Mary Lucy Marques"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands"
      ],
      "name": "Miranda van Lunteren"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands",
        "Department of Rhuematology, Ghent University Hospital, Ghent, Belgium"
      ],
      "name": "Manouk de Hooge"
    },
    {
      "affiliations": [
        "Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands"
      ],
      "name": "Monique Reijnierse"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Clinical Sciences Malmö, Lund University, Malmö, Sweden"
      ],
      "name": "Sofia Exarchou"
    },
    {
      "affiliations": [
        "Center for Treatment of Rheumatic and Musculoskeletal Diseases (REMEDY), Diakonhjemmet Hospital, Oslo, Norway"
      ],
      "name": "Inger Jorid Berg"
    },
    {
      "affiliations": [
        "Department of Medicine-DIMED, Rheumatology unit, University of Padova, Padova, Italy"
      ],
      "name": "Roberta Ramonda"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Amsterdam University Medical Center, Amsterdam, The Netherlands",
        "Department of Rheumatology, Zuyderland Medical Center, Heerlen, The Netherlands"
      ],
      "name": "Robert Landewé"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands"
      ],
      "name": "Floris A van Gaalen"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands"
      ],
      "name": "Désirée van der Heijde"
    },
    {
      "affiliations": [
        "Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands",
        "Department of Rheumatology, Zuyderland Medical Center, Heerlen, The Netherlands"
      ],
      "name": "Sofia Ramiro"
    }
  ],
  "title": "Which definitions for MRI sacroiliac joint lesions predict the diagnosis of early axial spondyloarthritis best? A 2-year follow-up in the SPACE cohort",
  "uid": "7eee5602-8ff1-5796-a099-f887a6cb62ce"
}