24 Oct Antibiotics In Childhood Linked To Higher Teenage Body Mass
MedicalResearch.com Interview with:
Brian S. Schwartz, MD, MS
Professor of Environmental Health Sciences, Epidemiology, and Medicine
Co-director, Program on Global Sustainability and Health
Senior Investigator, Geisinger Center for Health Research (Danville, PA)
Johns Hopkins Bloomberg School of Public Health
Baltimore, Maryland 21205
Medical Research: What is the background for this study? What are the main findings?
Dr. Schwartz: Sub-therapeutic doses of antibiotics (not a high enough dose to treat an infection in the animal) have been added to animal feeds for decades to promote weight gain. An increasing number of studies of therapeutic uses of antibiotics in humans have reported weight gain, mostly in young children. Using electronic health record data on over 163,000 children between 3 and 18 years of age from the Geisinger Health System, our study was the first one to study the full childhood age range among mostly healthy children; to find effects of antibiotics on weight gain at all ages; to find that the more the cumulative number of antibiotics the greater the weight gain; and that some of the effects were progressive, in that the cumulative number of antibiotics caused an increasing divergence of the body mass index trajectory over time from the trajectory in children who had not received antibiotics.
Medical Research: What should clinicians and patients take away from your report?
Dr. Schwartz: Although the average weight gain at 15 years of 3 pounds or so might seem small, keep in mind a few issues.
First, this is the average; many children will have much more weight gain and some will have less. But a shift in the distribution of BMIs to higher levels means there will be many more kids on a population level in what we call the “tails” of the distribution. Think about two bell-shaped curves, one shifted slightly to the right. There are many more kids in the right tail of the shifted distribution – that means there are many more obese children.
Second, our estimate is likely the lower bound of the average weight gain. There are many reasons to think that we under-estimated it, because we did not observe any of the children for the entire 15 year period; children were only observed on average for around four years; we did not have complete early life antibiotic use histories, when the effect may be stronger, because not all children were born at the Geisinger Health System; and we know that for certain antibiotics the effect was much stronger (this means, for example, that by including all antibiotics, we combined some that may not do this with some that do it much more strongly, thus diluting the overall effect).
Third, our models suggest that the effect likely continues into adulthood and the BMI trajectories of children who did and did not receive antibiotics are increasingly diverging at older ages. Although we did not observe children past 18 years, I would bet that this kind of pattern would continue.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Schwartz: Our research group and others are looking into these findings further in several types of studies. First, our study looked at antibiotics only in the child. Studies are needed that look at antibiotics in the mother during pregnancy as well. In addition, studies are needed that incorporate information on both delivery mode and breastfeeding, two practices that also affect the child’s microbiota development. We were able to include information on delivery mode on a subset of our children but did not have complete information on breastfeeding. Finally, research is needed on how the effects we observed may be happening, specifically regarding changes in the gastrointestinal microbiota before and after antibiotics and how antibiotic use over time influences the development of the microbiota over time.
B S Schwartz, J Pollak, L Bailey-Davis, A G Hirsch, S E Cosgrove, C Nau, A M Kress, T A Glass, K Bandeen-Roche. Antibiotic use and childhood body mass index trajectory. International Journal of Obesity, 2015; DOI:10.1038/ijo.2015.218
Brian S. Schwartz, MD, MS (2015). Antibiotics In Childhood Linked To Higher Teenage Body Mass