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Transient growth deceleration in normal short children. A potential source of bias in growth studies
C Polychronakos1, H Abu-Srair, H J Guyda
1Department of Paediatrics, McGill University, Montreal, Quebec, Canada.
Insights
Growth hormone testing in short children may appear to stimulate growth due to temporary growth deceleration, not a true therapeutic effect. This highlights potential selection bias in growth studies.
Area of Science:
- Pediatrics
- Endocrinology
- Growth Disorders
Background:
- Short stature is a common concern in pediatric endocrinology.
- Evaluation for growth hormone deficiency (GHD) is a standard diagnostic process.
- Transient growth decelerations are common in childhood.
Purpose of the Study:
- To investigate the growth velocity of short children initially evaluated for growth hormone deficiency but found not to be deficient.
- To identify potential biases in studies assessing growth-stimulating treatments using a within-subject control design.
Main Methods:
- Retrospective analysis of 21 short children's growth data.
- Evaluation of growth velocity for at least six months before and after diagnostic testing.
- Absence of specific therapeutic interventions during the evaluation period.
Main Results:
- A significant increase in growth velocity was observed after the diagnostic testing period.
- This increase occurred without any specific growth-stimulating interventions.
- The observed effect is attributed to selection bias inherent in the testing process.
Conclusions:
- The apparent "therapeutic" effect of growth hormone testing is likely a result of selection bias.
- Children are often tested after a period of slow growth, which is frequently transient.
- Growth studies using children as their own controls require careful interpretation due to potential biases.
Abstract:
We have examined the records of 21 short children evaluated for growth hormone deficiency and found not to be deficient. Their growth velocity was evaluated for at least 6 months, both before and after testing. Without any specific therapeutic intervention, growth velocity was significantly higher after testing, as compared with before. We attribute this apparent "therapeutic" effect of testing to a selection bias, due to the fact that, in normal clinical practice, children are selected for testing immediately following a period of slow growth, and that decelerations of growth are very often transient. Studies of growth-stimulating treatments using children as their own controls should, for this reason, be interpreted with caution.