In June of this year, we ran two articles that generated a bit of controversy using “big data” sets to show a possible association between phototherapy and childhood cancers (10.1542/peds.2015-1353 and 10.1542/peds.2015-1354) A commentary by Frazier et al. (10.1542/peds.2016-0983) helped show how minimal the absolute risk of cancer really was and described the limitations of the available datasets.
This week we are publishing another “big data” study by Wu et al. (10.1542/peds.2016-1813) to examine the hypothesis that either phototherapy or hyperbilirubinemia might carry an increased risk of autism. The study involved a retrospective cohort of over 500,000 infants born in the Kaiser Permanente northern California hospital system between 1995 and 2011. Children with the diagnosis of an autism spectrum disorder (ASD) (with appropriate confounding variables controlled for) were then categorized as having had or not had phototherapy for hyperbilirubinemia during their infancy.
In the overall birth cohort, 2% had an elevated bilirubin over 20 and 8% received phototherapy. Although initial data showed a relative risk that was significant between ASD and phototherapy, the strength of this association disappeared once confounders were controlled for. Normally we don’t give the “big reveal” of an article’s findings in our blog postings, but this time we think it’s important to do so to prevent anyone from walking away from our study summary thinking it had a positive finding when it did not.
Nonetheless with studies like this trying to implicate phototherapy as being associated with unpleasant outcomes, rather than take the data at its word, you might do better spending your time deciding whether a baby really need phototherapy or not and use evidence-based care guidelines (such as those offered by the AAP) Technical Report: Phototherapy to Prevent Severe Neonatal Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation. Reaffirmed July 2014 to choose wisely and not just place a baby under lights because their levels are approaching rather than actually reaching a concerning level. If families ask you about the autism risk of phototherapy or an elevated bilirubin, hopefully this study will turn the lights off on their concern.