Juvenile dermatomyositis (DM) significantly impairs growth and pubertal development in affected individuals, according to study results published in Arthritis Care & Research.
Investigators analyzed data from the Pediatric Rheumatology International Trials Organization (PRINTO), a prospective observational cohort study operating in 31 countries. The study enrolled 275 patients aged <18 years with active juvenile DM between 2001 and 2004. Follow-up visits were conducted regularly, with a median total follow-up time of 26 months. Patient height and weight were captured at study visits and standardized to Z-scores using the least mean squares method. Height Z-scores were adjusted for parental height, which was captured either at clinic visits or by self-report. Growth failure was defined as a parent-adjusted height Z score of -1.5; height deflection was defined as a change in height Z score of <-0.25 per year.
Using Tanner stages, investigators also assessed pubertal maturity stage at each study visit. Delayed puberty was defined as a delay in pubertal onset, pubertal tempo, or menarche.
Logistic regression was performed to evaluate the effect of baseline characteristics and juvenile DM on height, weight, and pubertal development. Patients without repeated height measurement data were excluded. Multiple imputation was used to account for visits at which height or pubertal data were missing.
The present analysis comprised 196 (71%) of 275 participants. The majority of children were from Western Europe (55.6%) and South and Central America (25.5%), though participants were also recruited from Eastern Europe (13.8%), and North America (5.1%). Almost all (94.9%) participants had received corticosteroids at some point during treatment. Median cumulative oral corticosteroid dose over follow-up was 279 mg/kg (range, 45-985 mg/kg).
Compared with baseline, parent-adjusted height Z scores were significantly reduced at 6- and 14-month follow-up visits for both girls (P <.0001) and boys (P =.001). However, the difference between baseline and 26 months was not significantly different, suggesting that “catch-up growth” occurred. Median body mass index (BMI) increased significantly across the study period, with peak growth observed 6 months after baseline (P <.0001). Girls with disease duration ≥12 months had significantly lower parent-adjusted height Z-scores (P =.002) and were less likely to experience catch-up growth. The same trend was not observed in boys. At final study visit, growth failure was observed in 21% of girls and 15% of boys; height deflection was observed in 25% of girls and 31.3% of boys. Among the 86 children with evaluable pubertal data, 36.0% displayed delayed puberty: 36.4% of girls (n=55) and 35.5% of boys.
Overall, 94 (48.0%) of 196 children displayed either growth failure, height deflection, and/or delayed puberty across the study period. In multivariable models, growth failure at baseline was the strongest risk factor for later growth failure (odds ratio [OR], 14.6; 95% CI, 5.6-38.2) and for delayed puberty (OR, 7.4; 95% CI, 2.3-24.6).
These data demonstrate a substantial risk for height deflection, increased BMI, and delayed development among children with juvenile DM. As study limitations, investigators noted that 2-year follow-up may not be sufficient to fully assess pubertal growth in participants. In addition, growth failure rates at final follow-up were not significantly different from rates observed at baseline, suggesting that corticosteroid doses were well tolerated.
“Our findings suggest that once a patient [with juvenile DM] has growth failure it may be more difficult to achieve catch-up growth, and they have an increased risk of further growth impairment,” the investigators wrote.
Disclosure: Two study authors declared affiliations with the pharmaceutical industry.
Please see the original reference for a full list of authors’ disclosures.
Nordal E, Pistorio A, Rygg M, et al; Paediatric Rheumatology International Trials Organisation. Growth and puberty in juvenile dermatomyositis: a longitudinal cohort study. Arthritis Care Res (Hoboken). 2020;72(2):265-273.