Opioid neonatal abstinence syndrome: controversies and implications for practice.

The Opioid Neonatal Abstinence Syndrome (NAS) is a term used to describe a cluster of signs and symptoms seen in infants experiencing withdrawal from opioid drugs. Despite a substantial literature the relationship between maternal methadone dose, NAS and the method of assessment of NAS symptoms has not been agreed. The following review will address current and historical controversies surrounding these issues and will examine the evidence concerned with the evaluation of neonates exposed to methadone in utero. The key findings are as follows: A variety of NAS scales are used to assess the severity of neonatal withdrawal symptoms including locally adapted validated tools. Inconsistencies in the use of NAS scales have included the timing, duration and frequency of administration; the degree to which observers were trained to reliability; the use of NAS scales designed for term neonates to assess pre-term neonates who may have a qualitatively different expression of abstinence symptoms and; the research setting in which the tool was administered. There is a lack of research investigating the observant bias' effect upon scoring NAS, the basis for treatment decisions and the influence of concomitant maternal use of non-opioid drugs late in pregnancy. We also discuss the implications of the lack of recognition of NAS symptoms leading to possible under reporting and inappropriate, early neonatal discharge from hospital. In addition, this paper also discusses the merits and problems of conducting research in this area and highlights gaps in our knowledge and areas for further research.