Research in context
Evidence before this study
We searched MEDLINE and Cochrane controlled trial register (last search done on Sept 18, 2015) for original research and meta-analyses describing the association between anaesthesia exposure in early life and neurodevelopmental outcome. We used combinations of the search terms “anesthesia”, and “child development”, or “learning disorders”. The search found no randomised trials but several cohort studies. Several reviews have concluded that there is an association between anaesthesia in childhood and neurodevelopmental outcome. Findings of two meta-analyses have shown an association between anaesthesia in children and a range of neurodevelopmental outcomes. All reviews and meta-analyses acknowledge the weaknesses of the cohort studies; including strong likelihood of confounding, bias, heterogeneous populations at times of exposure, and heterogeneous outcome measures, some of which are poorly defined or insensitive. All reviews conclude that causation cannot be established or excluded.
Added value of this study
We report results from the first randomised controlled trial assessing the effect of general anaesthesia in infancy on neurodevelopmental outcome. We used the best measure of neurodevelopment available to assess 2-year-old children, and noted strong evidence for equivalence between the use of awake-regional anaesthesia and just less than 1 h of general anaesthesia. However, it should be noted that this was an analysis of a secondary outcome with the primary outcome planned at 5 years of age, and in view of the limited sensitivity of developmental assessment at 2 years of age, this trial does not provide the definitive answer.
Implications of all the available evidence
Although there are some limitations that should be noted when interpreting the trial, the randomised prospective design adds substantially to the weight that should be given to the results compared with the mixed results found in previous cohort studies. However, reassessment at an older age is necessary before definitive conclusions can be drawn. The trial does not rule out the possibility that longer or many exposures to anaesthesia in early childhood can cause neurodevelopmental changes. Further research is needed to address these questions.