Background/Purpose: The impetus for this investigation was the specific questions from parents of JM patients pertaining to the physician’s expectations about their child’s disease course. The data in this study provides a window with which to study the anatomy of the first five years of response to current therapies available for JM children, classified by Myositis Specific Antibody (MSA).

Methods: Two groups: inception patients since diagnosis (n=36); referral patients (n=65) were assessed at diagnosis/referral and at 6, 12, 24, 36, 60 months. MSA was determined by immunoprecipitation and immunoblot (Oklahoma Research Lab). Nailfold capillary end row loops (ERL) were assayed using a Nikon Coolpix P6000 camera attached to a Dermlite II ProHR (18x). TNF-α-308 (A/G) polymorphisms in the promotor region were determined as previously reported. Calcifications: Physician inspection identified the calcific deposits, or when clinically appropriate, they were located by radiographic study, and designated as mild, moderate or severe. Lunar Prodigy measured bone mineral density. Data Collection and Analysis: Study data was prospectively obtained and stored in a MEDLOG database. Statistical analysis was performed using R version 3.3.1(www.r-project.org). For each clinical variable, a two sample t-test or the Wilcoxon Rank Sum test was performed as appropriate for the comparison between two defined patient groups. To test for the equality of more than two means, Tukey’s HSD test in conjunction with ANOVA was performed for all pairwise comparisons among means

Results: The 2 groups were similar: myositis onset age, race, gender, duration of untreated disease, abnormal MRI and initial Disease Activity Scores (DAS). The inception group had higher values for SGOT (p=0.008), CPK (p=0.014), LDH (p=0.0014), aldolase (p=0.0076) and neopterin (p=0.0033) than the referred. By 60 months, the referral DAS total score > inception (p=0.05). Myositis specific antibody (MSA) frequencies for the 93 juvenile dermatomyositis (JDM): negative (33.3%); combination of anti p155/140 and ant-Mi-2 (positive or indeterminate) (6.5%); p155/140+ (40.9%), Mi-2 (6.5%); MJ (11.8%), MDA5 (1.1%). The eight U1RNP overlap myositis patients had a higher DAS muscle score at 60 months than MSA negative (p=0.008), and anti p155/140 (p=0.002). Disease/treatment related damage: cataracts (35%), lipodystrophy (30%), fractures (28%), abnormal pulmonary function (2/19 tested; 10.3%), and calcification (17%). At 60 months, chronic calcifications (n=7) were associated with decreased mean nailfold capillary end-row loop (ERL) count (p=0.002) and lipodystrophy (p=0.027).

Conclusion:

Conclusion: 1) At 60 months, referral JDM and overlap patients each had a higher DAS, but all patients improved; 2) 21.7% had > 1 MSA; 3) cataracts and lipodystrophy were each present in 30% patients; 4) ERL count ≤5 was associated with calcinosis; 5) lipodystrophy was associated with calcinosis, but not ERL count.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/101-juvenile-myositis-patients-characterized-by-myositis-specific-antibodies-disease-activity-and-damage-over-60-months/