The PRINTO criteria for clinically inactive disease in juvenile dermatomyositis

Abstract

Objectives To develop data-driven criteria for clinically inactive disease on and off therapy for juvenile dermatomyositis (JDM). Methods The PRINTO database contains 275 patients with active JDM evaluated prospectively up to 24 months. Thirty-eight patients off therapy at 24 months were defined as clinically inactive and included in the reference group. These were compared with a random sample of 76 patients who had active disease at study baseline. Individual measures of muscle strength/endurance, muscle enzymes, physician's and parent's global disease activity/damage evaluations, inactive disease criteria derived from literature, and other ad hoc criteria, were evaluated for sensitivity, specificity, and Cohen's kappa agreement. Results The individual measures that best characterised inactive disease (sensitivity and specificity >0.8 and Cohen's K>0.8) were manual muscle testing (MMT)≥78, physician global assessment of muscle activity=0, physician global assessment of overall disease activity (PhyGloVAS) ≤0.2, the Childhood Myositis Assessment Scale (CMAS) ≥48, the Disease Activity Score (DAS) ≤3 and the Myositis Disease Activity Assessment Visual Analogue Scale (MYOACT) ≤0.2. The best combination of variables to classify a patient as being in a status of inactive disease on or off therapy is at least 3 out of 4 of the following criteria: creatine kinase ≤150, CMAS≥48, MMT≥78, and PhyGloVAS≤0.2. After 24 months, 30/31 (96.8%) patients were inactive off therapy and 69/145 (47.6%) were inactive on-therapy. Conclusion PRINTO established data-driven criteria, with clearly evidence-based cut off values, to identify JDM patients with clinically inactive disease. These criteria can be used in clinical trials, in research and in clinical practice.

Modelling disease activity in juvenile dermatomyositis: A Bayesian approach

“…Moreover, to better understand the predictive ability of the model, we consider the posterior predictive probability https://mc.manuscriptcentral.com/smmr 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 of an observation falling beyond the cut off point for pathological values for each of the four longitudinal outcomes, as defined in literature (i.e. >150 for CK, <48 for CMAS, <78 for MMT8 and >0.2 for PGA; note that these cut off points are defined on the original measurement scale 10 ). These predictions concern pathological values and are, therefore, relevant from a clinical point of view.…”

“…The serum level of this enzyme is usually elevated in active JDM, but tends to be relatively low 3 . Its theoretical range is in (0,∞) and values exceeding 150 U/L are considered pathological 10 . Many laboratories report a censored value of <20 U/L if the level is below the laboratory's detection limit.…”

“…A predefined number of points is assigned based on the performance of the child and the total CMAS score is the sum over all tasks, ranging from 0 to 53, with a lower score indicating more active disease. Scores of at least 48 points are considered normal 10 .…”

“…The total MMT8 is the sum over all muscle groups, thus ranging from 0 to 80, with a lower score indicating higher disease activity. A value of at least 78 points is considered normal 10 .…”

“…The PGA ranges from 0.0, indicating no disease activity, to 10.0, indicating maximal disease activity. The PGA should be at most 0.2 points to be considered normal 10 .…”