In Reply We write to report an error in our meta-analysis, “Breastfeeding and Childhood Leukemia Incidence: A Meta-Analysis and Systematic Review,”1 which was published online on June 1, 2015, and to reply to letters commenting on potential confounders. First, we had incorrectly included in our meta-analysis 2 studies2,3 that reported on the same cases and controls. Our search of the literature identified these 2 relevant studies, which were published in 20012 and 2012,3 respectively, and which had different numbers of cases (1636 vs 642) and controls (6959 vs 991), respectively. Although we were aware that both studies derived their study participants from the same national pool, we had mistakenly assumed that each study represented different cases and controls, as it was not explicitly indicated that the participants in the 2012 study were a subset of those in the 2001 study.
Efrat L. Amitay, Lital Keinan-Boker. Breastfeeding and Childhood Leukemia Incidence—Reply. JAMA Pediatr. 2015;169(11):1071–1072. doi:10.1001/jamapediatrics.2015.2643