Response Criteria for Juvenile Dermatomyositis

Measures to assess disease activity in juvenile dermatomyositis had been established and validated by the International Myositis Assessment and Clinical Studies Group (IMACS) and the Pediatric Rheumatology INternational Trials Organization (PRINTO). The American College of Rheumatology and the European League Against Rheumatism provisionally endorsed these core measures.

The various societies and work groups used different criteria in their individual guidelines for judging clinical response in juvenile dermatomyositis, and various core measures were combined in an effort to increase sensitivity and decrease the sample sizes needed.

Even though these preliminary responses in juvenile dermatomyositis criteria improved assessment of patients’ responses to treatment, they were limited by their differences, a lack of randomized trial data, and a lack of final consensus.

For these reasons, Lisa Rider and colleagues, in a multinational effort between the IMACS and the PRINTO, published the fully validated response criteria for juvenile dermatomyositis for 2016 in a recent Annals of the Rheumatic Diseasesarticle.

The study

Candidate definitions were evaluated by the working group using consensus profile ratings to assess sensitivity, specificity, and area under the curve to validate the definition’s performance as a tool to measure clinical response. Thresholds for minimal, moderate, and major improvement were developed.

Results

• 312 candidate definitions for response to treatment in juvenile dermatomyositis were examined; 101 displayed excellent performance for minimal improvement (sensitivity and specificity, ≥ 80%, and area under the curve, ≥ 0.90).

• 30 candidate definitions also performed well in 2 clinical trials, showing statistically significant differentiation between treatment arms (P<0.05) and treating physician’s improvement scores at 24 weeks (P<0.001).

• Of the 101 high-performance definitions, 14 top performers were considered by the pediatric working group.

• Of the 14 definitions considered, 9 were categorical and set criteria for minimal, moderate, and major improvement and 5 were continuous definitions where points were given on a scale corresponding to the magnitude of improvement within the categories of minimal, moderate, and major improvement.

• All definitions presented to the working group had ≥ 87% sensitivity and specificity (area under the curve, ≥ 0.09) for minimal improvement and ≥ 80% and 75% (area under the curve, ≥ 0.88 and 0.84) for moderate and major improvement, respectively.

• Nearly all candidate definitions were validated at 6 months using the PRINTO trial when differentiating between treatment arms for minimal improvement (P<0.05).

• All candidate definitions were validated in 48 patients with juvenile dermatomyositis in the Rituximab in Myositis trial, and all were able to differentiate the median treating physician’s improvement score at 24 weeks (P≥0.006).

Final criteria

Ultimately, 6 core measures were agreed upon. A composite score from all 6 represented the total improvement score. Following are the core measures and their improvement scores:

(1)Physician global activity: worsening to 5% improvement, 0; > 5% to 15%, 7.5; > 15% to 25%, 15; > 25% to 40%, 17.5; > 40%, 20.

(2) Parent global activity: worsening to 5% improvement, 0; > 5% to 15%, 2.5; > 15% to 25%, 5; > 25% to 40%, 7.5; > 40%, 10.

(3) Manual muscle testing or Childhood Myositis Assessment Scale: worsening to 2% improvement, 0; > 2% to 10%, 10; > 10% to 20%, 20; > 20% to 30%, 27.5; > 30%, 32.5.

(4) Childhood Health Assessment Questionnaire: worsening to 5% improvement, 0; > 5% to 15%, 5; > 15% to 25%, 7.5; > 25% to 40%, 7.5; > 40%, 10.

(5) Enzyme (most abnormal) or Physical Summary Score of the Child Health Questionnaire-Parent Form 50: worsening to 5% improvement, 0; > 5% to 15%, 2.5; > 15% to 25%, 5; > 25% to 40%, 7.5; > 40%, 7.5.

(6) Extra-muscular activity or Disease Activity Score: worsening to 5% improvement, 0; > 5% to 15%, 7.5; > 15% to 25%, 12.5; > 25% to 40%, 15; > 40%, 20.

In juvenile dermatomyositis, total improvement scores of ≥ 30, ≥ 45, and ≥ 70 represent minimal, moderate, and major improvement, respectively.

For adults, total improvement scores of ≥ 20, ≥ 40, and ≥ 60 were used to represent minimal, moderate, and major improvement, respectively.

Conclusions

The work group concluded:

• The IMACS or the PRINTO core measures may be used.

• The conjoint analysis-based continuous response criteria based on absolute percent change in the core measures above should be used as the thresholds for minimal, moderate, and major improvement in future dermatomyositis/polymyositis trials.

Disclosures:

This project was supported by the American College of Rheumatology, the European League Against Rheumatism, the NIH, Istituto G. Gaslini, the Paediatric Rheumatology INternational Trials Organization, Cure JM Foundation, Myositis UK, the Myositis Association, and the Ministry of Health, Czech Republic.

References:

Lisa G. Rider, Rohit Aggarwal, Angela Pistorio, et al. “2016 American College of Rheumatology/European League Against Rheumatism Criteria for Minimal, Moderate, and Major Clinical Response in Juvenile Dermatomyositis: An International Myositis Assessment and Clinical Studies Group/Paediatric Rheumatology International Trials Organisation Collaborative Initiative.” Ann Rheum Dis. 2017;76:782-791. doi: 10.1136/annrheumdis-2017-211401.