Review Article | Published:

Update on outcome assessment in myositis

Nature Reviews Rheumatology volume 14, pages 303318 (2018) | Download Citation


The adult and juvenile myositis syndromes, commonly referred to collectively as idiopathic inflammatory myopathies (IIMs), are systemic autoimmune diseases with the hallmarks of muscle weakness and inflammation. Validated, well-standardized measures to assess disease activity, known as core set measures, were developed by international networks of myositis researchers for use in clinical trials. Composite response criteria using weighted changes in the core set measures of disease activity were developed and validated for adult and juvenile patients with dermatomyositis and adult patients with polymyositis, with different thresholds for minimal, moderate and major improvement in adults and juveniles. Additional measures of muscle strength and function are being validated to improve content validity and sensitivity to change. A health-related quality of life measure, which incorporates patient input, is being developed for adult patients with IIM. Disease state criteria, including criteria for inactive disease and remission, are being used as secondary end points in clinical trials. MRI of muscle and immunological biomarkers are promising approaches to discriminate between disease activity and damage and might provide much-needed objective outcome measures. These advances in the assessment of outcomes for myositis treatment, along with collaborations between international networks, should facilitate further development of new therapies for patients with IIM.

Key points

  • The primary assessment of myositis includes core set measures of disease activity and disease damage and measures of patient-reported outcomes.

  • A new composite myositis response criterion, which combines and differentially weights core set activity measures to determine minimal, moderate and major clinical response, has been developed and validated.

  • Measures of muscle strength and function are being refined for myositis subgroups and are being used as primary or secondary outcome measures in studies and clinical trials in patients with myositis.

  • Disease-specific patient-reported outcomes, including health-related quality of life measures that reflect patient perspectives, are being developed.

  • Imaging and immunological biomarkers provide objective measures that can discriminate disease activity from disease damage, but they still require validation in clinical trials.

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The authors thank L. Maroski for assistance with references and tables, M. Ward and P. Grayson for helpful comments on the manuscript and J. Morrow for providing the MRI figure. L.G.R. was supported by the intramural research programme of the US National Institutes of Health, National Institute of Environmental Health Sciences. P.M.M. was supported by the UK National Institute for Health Research (NIHR) University College London Hospitals Biomedical Research Centre. The views expressed are those of the authors and not necessarily those of the UK National Health Service (NHS), the NIHR, the UK Department of Health or the US Department of Health and Human Services.

Author information


  1. Environmental Autoimmunity Group, National Institute of Environmental Health Sciences, US National Institutes of Health, Bethesda, MD, USA.

    • Lisa G. Rider
  2. Department of Medicine, Division of Rheumatology and Clinical Immunology, University of Pittsburgh, Pittsburgh, PA, USA.

    • Rohit Aggarwal
  3. Centre for Rheumatology and MRC Centre for Neuromuscular Diseases, University College London, London, UK.

    • Pedro M. Machado
  4. Institut de Myologie, GH Pitié-Salpêtrière, Paris, France.

    • Jean-Yves Hogrel
  5. Department of Pediatrics, Duke University School of Medicine, Durham, NC, USA.

    • Ann M. Reed
  6. Division of Rheumatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.

    • Lisa Christopher-Stine
  7. Istituto Giannina Gaslini, Clinica Pediatria e Reumatologia, PRINTO, Genoa, Italy.

    • Nicolino Ruperto


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All authors researched the data for the article, provided substantial contributions to discussions of its content, wrote the article and reviewed and/or edited the manuscript before submission.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Lisa G. Rider.

Supplementary information

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  1. 1.

    Supplementary Table S1

    Performance characteristics of existing patient-reported outcomes used in studies of the idiopathic inflammatory myopathies, according to the OMERACT Filter 1.0


Patient-reported outcome measures

(PROMs). Measurements based on information provided directly by the patient (that is, the study subject) about the status of his or her health condition, without amendment or interpretation of the patient's response by a clinician or anyone else.

Health-related quality of life

(HRQoL). A multidimensional assessment of a subject's health that includes domains related to physical, mental, emotional and social functioning. HRQoL goes beyond direct measures of health, life expectancy and causes of death and focuses on the effect that health status has on quality of life.


Measurable indicators of normal biological processes, pathogenic processes or responses to an exposure or intervention, including therapeutic interventions.

Core set measures

(CSMs). The minimum set of validated assessments that are recommended to be used in therapeutic trials and natural history studies.

Response criteria

A set of conditions, usually involving combinations of assessment tools, that define clinically important improvement in disease symptoms and signs. These criteria allow investigators, clinicians, regulators and patients to determine the efficacy (or lack thereof) of a therapeutic intervention, and they facilitate communication between these parties about response to treatment by using the same metric.

Manual muscle testing

(MMT). A method for assessing the strength of individual muscle groups on the basis of performing a movement in relation to the forces of gravity and manual resistance by the examiner.


Devices that measure muscle strength during muscle contraction, such as gripping, pushing and pulling.

Magnetic resonance imaging

(MRI). An imaging technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within the body.

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