Cardwell, Chris R and Stene, Lars C and Ludvigsson, Johnny and Rosenbauer, Joachim and Cinek, Ondrej and Svensson, Jannet and Perez-Bravo, Francisco and Memon, Anjum and Gimeno, Suely G and Wadsworth, Emma J K and Strotmeyer, Elsa S and Goldacre, Michael J and Radon, Katja and Chuang, Lee-Ming and Parslow, Roger C and Chetwynd, Amanda and Karavanaki, Kyriaki and Brigis, Girts and Pozzilli, Paolo and Urbonaite, Brone and Schober, Edith and Devoti, Gabriele and Sipetic, Sandra and Joner, Geir and Ionescu-Tirgoviste, Constantin and de Beaufort, Carine E and Harrild, Kirsten and Benson, Victoria and Savilahti, Erkki and Ponsonby, Anne-Louise and Salem, Mona and Rabiei, Samira and Patterson, Chris C (2012) Breast-Feeding and Childhood-Onset Type 1 Diabetes : A pooled analysis of individual participant data from 43 observational studies. Diabetes Care, 35 (11). pp. 2215-2225. ISSN 1935-5548
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Abstract
OBJECTIVE To investigate if there is a reduced risk of type 1 diabetes in children breastfed or exclusively breastfed by performing a pooled analysis with adjustment for recognized confounders. RESEARCH DESIGN AND METHODS Relevant studies were identified from literature searches using MEDLINE, Web of Science, and EMBASE. Authors of relevant studies were asked to provide individual participant data or conduct prespecified analyses. Meta-analysis techniques were used to combine odds ratios (ORs) and investigate heterogeneity between studies. RESULTS Data were available from 43 studies including 9,874 patients with type 1 diabetes. Overall, there was a reduction in the risk of diabetes after exclusive breast-feeding for >2 weeks (20 studies; OR = 0.75, 95% CI 0.64-0.88), the association after exclusive breast-feeding for >3 months was weaker (30 studies; OR = 0.87, 95% CI 0.75-1.00), and no association was observed after (nonexclusive) breast-feeding for >2 weeks (28 studies; OR = 0.93, 95% CI 0.81-1.07) or >3 months (29 studies; OR = 0.88, 95% CI 0.78-1.00). These associations were all subject to marked heterogeneity (I(2) = 58, 76, 54, and 68%, respectively). In studies with lower risk of bias, the reduced risk after exclusive breast-feeding for >2 weeks remained (12 studies; OR = 0.86, 95% CI 0.75-0.99), and heterogeneity was reduced (I(2) = 0%). Adjustments for potential confounders altered these estimates very little. CONCLUSION The pooled analysis suggests weak protective associations between exclusive breast-feeding and type 1 diabetes risk. However, these findings are difficult to interpret because of the marked variation in effect and possible biases (particularly recall bias) inherent in the included studies.