medwireNews: A long-term follow-up study of children with Prader-Willi syndrome (PWS) has found no evidence to indicate that growth hormone (GH) therapy affects the risk or severity of scoliosis in this population.
“Based on these findings, scoliosis should neither be considered as a contraindication to start GH treatment, nor as a reason to discontinue GH or to lower the GH dose in children with PWS who develop scoliosis”, say Lionne Grootjen, from the Dutch Growth Research Foundation in Rotterdam, the Netherlands, and co-workers.
“Because of the high prevalence of scoliosis in PWS, it is recommended to perform X-rays and physical examination on regular basis”, they advise in the European Journal of Endocrinology.
The open-label study included 53 boys and 50 girls who received continuous GH therapy for a minimum of 8 years, from a median age of 2.8 years, and 23 age-matched children who did not receive GH.
“Because all Dutch children with PWS are nowadays treated with GH from a young age, we could only include a small number of untreated children”, the researchers explain.
Children given GH were significantly taller than the controls and more likely to be prepubertal after 8 years of follow-up (47.6 vs 78.3%).
Although the two groups were similar in terms of PWS genotype, total body bone mineral density (BMD), lumbar spine BMD and fat mass percentage, children given GH did have a higher ratio of trunk lean body mass to body surface area (LBM:BSA) – an indicator of relative muscle mass.
The incidence of scoliosis was comparable in the GH and control groups (77.7 vs 69.6%) and the two arms did not significantly differ with regard to median Cobb angle (18.0 vs 15.0 degrees), the likelihood of severe scoliosis (Cobb angle > 25 degrees, 38.8 vs 43.8%), or receipt of surgery (5.8 vs 8.7%) or a brace (5.8 vs 8.7%).
“Our data suggest that hypotonia is a main cause of scoliosis in children with PWS and not the catch-up growth after the start of GH treatment”, the team writes, adding “that higher lean body mass of the trunk may counteract the effect of the GH-induced accelerated growth on development of scoliosis in children with PWS.”
Among GH-treated children with and without scoliosis, there was no significant difference in median age at start of GH therapy (2.96 vs 2.51 years), height (–0.02 vs 0.78 standard deviation score [SDS]), trunk LBM:BSA ratio (8.94 vs 8.72), BMI (1.15 vs 1.61 SDS) or fat percentage (1.88 vs 2.16 SDS).
However, children with scoliosis did have significantly lower median total body BMD SDS (–0.56 vs 0.14) and a trend towards lower median bone mineral apparent density of the lumbar spine (BMAD LS, 0.28 vs 0.63 SDS).
Moreover, although total body BMD was not associated with Cobb angle, there was an inverse association between Cobb angle and BMAD LS after 8 years, the researchers say.
“Our study shows the importance of BMD-status in relation to scoliosis in children with PWS and we, therefore, advise to optimize BMD-status in children and adolescents with PWS”, say Grootjen and team.
The authors note that as GH treatment was begun at an early age, their group is still younger than the expected age for scoliosis treatment.
“It might be that prevalence of surgery or brace therapy in our study is an underestimation due to the relatively young age”, they write.
“Further longer-term studies on the effects of GH treatment on scoliosis development and progression in PWS are needed.”
By Lynda Williams
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