Early Exposure to Antibiotics Linked With Obesity

Antibiotic exposure early in life is strongly linked with an increased risk of childhood obesity, according to results from a large, retrospective, longitudinal cohort study presented at the 2015 Annual Meeting of the Pediatric Academic Societies (PAS). “Antibiotics may provide a physician-modifiable risk factor for obesity prevention in early childhood,” stated lead investigator Elizabeth Dawson-Hahn, MD, University of Washington, Seattle, Washington, speaking here on 26 April. “Children in the United States are frequently prescribed antibiotics,” she added. Previous studies have demonstrated an association between early antibiotic exposure and obesity, but these findings were limited by recall bias, exposure ascertainment, and lack of inclusion of maternal factors. Dr. Dawson-Hahn and colleagues evaluated the association between antibiotic exposure from birth to 47 months with weight status at 48 to 59 months of age, using electronic medical records between 2002 and 2010 from 4,938 subjects in the Group Health Cooperative database of Washington State. Of these subjects, 3,533 (72%) had been exposed to antibiotics. The Group Health integrated healthcare delivery-system database contains both healthcare and insurance-claims data, including pharmacy data, and is linked to birth-certificate data, allowing prescriptions to be linked to subject age. Antibiotic exposure was defined as any prescription for an oral antibiotic filled at a pharmacy for a subject between 0 and 47 months of age. Prescriptions for topical, intravenous, intramuscular, otic, and ophthalmic antibiotics were excluded. The primary outcome was the proportion of overweight and obese children as defined by the US Centres for Disease Control and Prevention growth-chart criteria at 48 to 59 months. Multivariate logistic regression assessed the association of antibiotic exposure and overweight (defined as body mass index [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][BMI] ?85th and ?95th percentile) or obesity (defined as BMI >95th percentile) at 48 to 59 months. The 2 models used were adjusted for maternal BMI, Medicaid status, childhood asthma diagnosis, delivery type, birth weight, race, and antenatal maternal outpatient antibiotic exposure. In model 1, the primary predictor was antibiotic exposure as a continuous variable. In model 2, the primary predictor was the timing of first antibiotic exposure (<12 months and 12 to 47 months) with no antibiotic exposure as the reference. The children’s mean birth weight was 3,443 g (interquartile range [IQR]: 3,119 to 3,799 g), and the mean gestational age was 39.0 weeks (IQR: 38 to 40 weeks). Antibiotic exposure at <12 months of age comprised 53% of the exposure group. At 48 to 59 months of age, 11% and 12% of children exposed and not exposed to antibiotics earlier in their lives, respectively, were overweight. The adjusted odds ratio (aOR) for overweight in model 1 was 1.03 (95% confidence interval [CI], 1.01 to 1.05; P = .005). The aOR for overweight in model 2 was 1.20 (95% CI, 1.01 to 1.42; P = .038) for antibiotic exposure during the first year of life and 0.76 (95% CI, 0.76 to 1.01; P = .071) for antibiotic exposure thereafter. The composite aOR for overweight was 1.10 (95% CI, 0.86 to 1.40).The rate of obesity in the antibiotic-exposed and unexposed children (5% and 3%, respectively) was significantly different (P < .05). The aOR for obesity at 48 to 59 months was 1.65 (95% CI, 1.04 to 2.60). Maternal use of oral antibiotics was associated with an aOR for obesity at 48 to 59 months of 1.61 (95% CI, 1.07 to 2.42). “In this large, longitudinal cohort, antibiotic exposure at birth to 47 months was associated with being overweight at 48 to 59 months, with exposure during infancy associated with higher odds,” said Dr. Dawson-Hahn. “Greater antibiotic exposure was associated with higher BMI z-score at 48 to 59 months. Antenatal maternal outpatient antibiotic exposure was also associated with obesity in the child,” she noted. Lack of recall bias was a strength of this study, the authors suggested. Limitations included lack of generalisation of the data, as the majority of the mothers were white and from high-income households. There was also a lack of information on breastfeeding, and an inability to include information on intravenous antibiotic use. All subjects in this study were enrolled in the Group Health database from birth, with continuous enrolment for 48 months, and availability of height and weight data at least once from 12 to 27 months and from 48 to 59 months. Subjects were excluded if they had a diagnosis of cystic fibrosis, malignancy, immunodeficiency, HIV infection, congenital heart disease, and/or Prader-Willi syndrome, all of which could involve the use of antibiotics. The proportion of males was 54% in the antibiotic-exposed group and 49% in the unexposed group, respectively (P < .001) and 51.8% overall. The prevalence of childhood asthma in the antibiotic-exposed group (16%) and unexposed group (5%) was significant (P < .0001). Maternal BMI was significantly different in the antibiotic-exposed group (27±6 kg/m2) versus the unexposed group (26±6 kg/m2) (P < .0001), as was the use of oral antibiotics during pregnancy (34.2% and 25.2%, respectively; P < .0001). Dr. Dawson-Hahn concluded that “Future studies should explore the mechanism of the relationship between early-life antibiotic exposure and obesity -- such as whether this association is due to changes in intestinal microbial composition.” DG News, 28 April 2015 ;http://dgnews.docguide.com ;[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]