Developing classification criteria for skin-predominant dermatomyositis: the Delphi process

BACKGROUND

The European League Against Rheumatism/American College of Rheumatology classification criteria for inflammatory myopathies are able to classify patients with skin-predominant dermatomyositis (DM). However, approximately 25% of patients with skin-predominant DM do not meet two of the three hallmark skin signs and fail to meet the criteria.

OBJECTIVES

To develop a set of skin-focused classification criteria that will distinguish cutaneous DM from mimickers and allow a more inclusive definition of skin-predominant disease.

METHODS

An extensive literature review was done to generate items for the Delphi process. Items were grouped into categories of distribution, morphology, symptoms, antibodies, histology and contextual factors. Using REDCap™, participants rated these items in terms of appropriateness and distinguishing ability from mimickers. The relevance score ranged from 1 to 100, and the median score determined a rank-ordered list. A prespecified median score cut-off was decided by the steering committee and the participants. There was a pre-Delphi and two rounds of actual Delphi.

RESULTS

There were 50 participating dermatologists and rheumatologists from North America, South America, Europe and Asia. After a cut-off score of 70 during the first round, 37 of the initial 54 items were retained and carried over to the next round. The cut-off was raised to 80 during round two and a list of 25 items was generated.

CONCLUSIONS

This project is a key step in the development of prospectively validated classification criteria that will create a more inclusive population of patients with DM for clinical research. What's already known about this topic? Proper classification of patients with skin-predominant dermatomyositis (DM) is indispensable in the appropriate conduct of clinical/translational research in the field. The only validated European League Against Rheumatism/American College of Rheumatology criteria for idiopathic inflammatory myopathies are able to classify skin-predominant DM. However, a quarter of amyopathic patients still fail the criteria and does not meet the disease classification. What does this study add? A list of 25 potential criteria divided into categories of distribution, morphology, symptomatology, pathology and contextual factors has been generated after several rounds of consensus exercise among experts in the field of DM. This Delphi project is a prerequisite to the development of a validated classification criteria set for skin-predominant DM.

The diagnosis and classification of amyopathic dermatomyositis: a historical review and assessment of existing criteria

BACKGROUND

Diagnostic criteria are used to identify a patient having a disease in a clinical setting, whereas classification criteria create a well-defined population for research purposes. The diagnosis and classification of amyopathic dermatomyositis (ADM) have not been recognized by most existing criteria for idiopathic inflammatory myopathies (IIMs). To address this, several criteria were proposed to define ADM either as a distinct disease entity or as a subset of the spectrum of IIMs.

OBJECTIVES

To discuss the diagnosis and classification of ADM and to assesses the available criteria in identifying cases of ADM and/or distinguishing it from dermatological mimickers such as lupus erythematosus.

METHODS

We conducted an extensive literature search using the PubMed database from June 2016 to August 2018, using the search terms 'amyopathic dermatomyositis', 'diagnosis' and 'classification'.

RESULTS

The European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) criteria, which are the only validated classification criteria for adult and juvenile IIM and their major subgroups, include three cutaneous items (Göttron sign, Göttron papules, heliotrope rash) to be able to classify ADM. This international and multispecialty effort is a huge step forward in the classification of skin-predominant disease in dermatomyositis. However, about 25% of the population with ADM do not meet two out of the three skin features and are misdiagnosed or classified as having a different disease entity, most commonly lupus erythematosus.

CONCLUSIONS

These gaps rationalize the continuous assessment and improvement of existing criteria and/or the development of validated, separate and skin-focused criteria for DM.

Evaluation of the reliability and validity of the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) in paediatric cutaneous lupus among paediatric dermatologists and rheumatologists

BACKGROUND

The Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) is a reliable outcome measure for cutaneous lupus erythematosus (CLE) in adults used in clinical trials. However, it has not been validated in children, limiting clinical trials for paediatric CLE.

OBJECTIVES

This study aimed to validate the CLASI in paediatrics.

METHODS

Eleven paediatric patients with CLE, six dermatologists and six rheumatologists participated. The physicians were trained to use the CLASI and Physician's Global Assessment (PGA), and individually rated all patients using both tools. Each physician reassessed two randomly selected patients. Within each physician group, the intraclass correlation coefficient (ICC) was calculated to assess the reliability of each measure.

RESULTS

CLASI activity scores demonstrated excellent inter- and intrarater reliability (ICC > 0·90), while the PGA activity scores had good inter-rater reliability (ICC 0·73-0·77) among both specialties. PGA activity scores showed excellent (ICC 0·89) and good intrarater reliability (ICC 0·76) for dermatologists and rheumatologists, respectively. Limitations of this study include the small sample size of patients and potential recall bias during the physician rerating session.

CONCLUSIONS

CLASI activity measurement showed excellent inter- and intrarater reliability in paediatric CLE and superiority over the PGA. These results demonstrate that the CLASI is a reliable and valid outcome instrument for paediatric CLE.