TY - JOUR
T1 - Birth order and childhood type 1 diabetes risk
T2 - A pooled analysis of 31 observational studies
AU - Cardwell, Chris R.
AU - Stene, Lars C.
AU - Joner, Geir
AU - Bulsara, Max K.
AU - Cinek, Ondrej
AU - Rosenbauer, Joachim
AU - Ludvigsson, Johnny
AU - Svensson, Jannet
AU - Goldacre, Michael J.
AU - Waldhoer, Thomas
AU - Jarosz-Chobot, Przemystawa
AU - Gimeno, Suely GA
AU - Chuang, Lee Ming
AU - Roberts, Christine L.
AU - Parslow, Roger C.
AU - Wadsworth, Emma JK
AU - Chetwynd, Amanda
AU - Brigis, Girts
AU - Urbonaite, Brone
AU - Šipetić, Sandra
AU - Schober, Edith
AU - Devoti, Gabriele
AU - Ionescu-Tirgoviste, Constantin
AU - de Beaufort, Carine E.
AU - Stoyanov, Denka
AU - Buschard, Karsten
AU - Radon, Katja
AU - Glatthaar, Christopher
AU - Patterson, Chris C.
N1 - Funding Information:
This pooled analysis was not directly funded but the authors acknowledge support for the conduct of the original studies from the following: the Czech Republic Ministry of Education (grant MSM 0021620814), Department of Health of Taiwan (DOH 90-TD1028), Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (grant 94/0943-0), The Swedish Child Diabetes Foundation, the NHS National Coordinating Centre for Research Capacity Development UK, Australian National Health and Medical Research Council (NHMRC) (project grant #457302), the Research Council of Norway, the German Research Foundation (grant HE 234/1-1), the Ministry for Science and Technological Development of Serbia (No. 145084, 2006-2010), EUBIROD funded by the European Commission Health Information Strand (DG-SANCO 2005, Contract No 2007115), Diabetes UK and the Northern Ireland Department of Health and Social Services.
PY - 2011/4
Y1 - 2011/4
N2 - Background: The incidence rates of childhood onset type 1 diabetes are almost universally increasing across the globe but the aetiology of the disease remains largely unknown. We investigated whether birth order is associated with the risk of childhood diabetes by performing a pooled analysis of previous studies. Methods: Relevant studies published before January 2010 were identified from MEDLINE, Web of Science and EMBASE. Authors of studies provided individual patient data or conducted pre-specified analyses. Meta-analysis techniques were used to derive combined odds ratios (ORs), before and after adjustment for confounders, and investigate heterogeneity. Results: Data were available for 6 cohort and 25 case-control studies, including 11 955 cases of type 1 diabetes. Overall, there was no evidence of an association prior to adjustment for confounders. After adjustment for maternal age at birth and other confounders, a reduction in the risk of diabetes in second-or later born children became apparent [fully adjusted OR=0.90 95% confidence interval (CI) 0.83-0.98; P=0.02] but this association varied markedly between studies (I2=67%). An a priori subgroup analysis showed that the association was stronger and more consistent in children <5years of age (n=25 studies, maternal age adjusted OR=0.84 95% CI 0.75, 0.93; I2=23%). Conclusion: Although the association varied between studies, there was some evidence of a lower risk of childhood onset type 1 diabetes with increasing birth order, particularly in children aged <5 years. This finding could reflect increased exposure to infections in early life in later born children. Published by Oxford University Press on behalf of the International Epidemiological Association
AB - Background: The incidence rates of childhood onset type 1 diabetes are almost universally increasing across the globe but the aetiology of the disease remains largely unknown. We investigated whether birth order is associated with the risk of childhood diabetes by performing a pooled analysis of previous studies. Methods: Relevant studies published before January 2010 were identified from MEDLINE, Web of Science and EMBASE. Authors of studies provided individual patient data or conducted pre-specified analyses. Meta-analysis techniques were used to derive combined odds ratios (ORs), before and after adjustment for confounders, and investigate heterogeneity. Results: Data were available for 6 cohort and 25 case-control studies, including 11 955 cases of type 1 diabetes. Overall, there was no evidence of an association prior to adjustment for confounders. After adjustment for maternal age at birth and other confounders, a reduction in the risk of diabetes in second-or later born children became apparent [fully adjusted OR=0.90 95% confidence interval (CI) 0.83-0.98; P=0.02] but this association varied markedly between studies (I2=67%). An a priori subgroup analysis showed that the association was stronger and more consistent in children <5years of age (n=25 studies, maternal age adjusted OR=0.84 95% CI 0.75, 0.93; I2=23%). Conclusion: Although the association varied between studies, there was some evidence of a lower risk of childhood onset type 1 diabetes with increasing birth order, particularly in children aged <5 years. This finding could reflect increased exposure to infections in early life in later born children. Published by Oxford University Press on behalf of the International Epidemiological Association
KW - Birth order
KW - Diabetes mellitus
KW - Epidemiology
KW - Meta-analysis
KW - Type 1
UR - http://www.scopus.com/inward/record.url?scp=79953723753&partnerID=8YFLogxK
U2 - 10.1093/ije/dyq207
DO - 10.1093/ije/dyq207
M3 - Article
C2 - 21149280
AN - SCOPUS:79953723753
SN - 0300-5771
VL - 40
SP - 363
EP - 374
JO - International Journal of Epidemiology
JF - International Journal of Epidemiology
IS - 2
M1 - dyq207
ER -
