Abstract
Objectives
Two studies reported an increased risk of autistic disorder in children conceived less than 12 months after a previous birth. Our objective was to examine the association between the interpregnancy interval (IPI) and autism spectrum disorder (ASD) in a Canadian cohort.
Methods
Using administrative datasets housed at the Manitoba Centre for Health Policy, we identified pairs of first- and second-born singleton siblings born between 1988 and 2005. Diagnoses of ASD were ascertained by searching physician billing claims, hospital discharge abstracts, education data, and a database containing information on individuals identified for a 2002–2007 ASD surveillance program in Manitoba. Logistic regression models were fit to examine the association between the IPI and ASD in 41,050 second-born siblings where the first-borns did not have ASD, using IPIs of ≥36 months as the reference category and specifying three case groups. Case Group 1 included individuals with at least one ASD code (n = 490); Case Group 2 included those with two or more ASD codes (n = 375); and Case Group 3 comprised individuals with a record in the ASD surveillance program database (n = 141).
Results
The adjusted odds ratios (ORs) for IPIs shorter than 12 months ranged from 1.22 (95% CI: 0.91–1.63) for Case Group 1 to 1.72 (95% CI: 0.96–3.06) for Case Group 3. When the case groups were restricted to individuals with more severe ASD, the ORs increased and were significant for Case Groups 1 and 2.
Conclusion
Our findings also support an association between short IPIs and more severe ASD.
Key Words: Autism, interpregnancy interval, secondary analysis, administrative data, record linkage, Manitoba Centre for Health Policy
Résumé
Objectifs
Deux études ont fait état d’un risque accru de trouble autistique chez les enfants conçus moins de 12 mois après une naissance antérieure. Notre objectif était d’examiner l’association entre la période de non-gravidité (PNG) et les troubles du spectre de l’autisme (TSA) au sein d’une cohorte canadienne.
Méthode
À l’aide de jeux de données administratives stockés au Centre de la politique des soins de santé du Manitoba, nous avons identifié des paires familiales composées du premier-né et du deuxième enfant (accouchements simples) nés entre 1988 et 2005. Les diagnostics de TSA ont été obtenus en interrogeant les demandes de paiement des médecins, les registres des sorties des hôpitaux, les données relatives à l’éducation et une base de données contenant de l’information sur les personnes identifiées pour un programme de surveillance des TSA mené au Manitoba entre 2002 et 2007. Des modèles de régression logistique ont été adaptés pour examiner l’association entre la PNG et les TSA chez 41 050 frères et soeurs second-nés dont le frère ou la soeur né(e) en premier n’avait pas de TSA, en utilisant une PNG de ≥ 36 mois comme catégorie de référence et en précisant trois groupes de cas. Le 1er groupe de cas incluait les personnes avec au moins un code de TSA (n = 490); le 2e groupe de cas incluait celles avec deux codes de TSA ou plus (n = 375); et le 3e groupe de cas comprenait les personnes ayant un dossier dans la base de données du programme de surveillance des TSA (n = 141).
Résultats
Le rapport de cotes (RC) ajusté pour les PNG de moins de 12 mois variait entre 1,22 (IC de 95%: 0,91–1,63) pour le 1er groupe de cas à 1,72 (IC de 95 %: 0,96–3,06) pour le 3e groupe de cas. Lorsque les groupes de cas étaient limités aux personnes ayant un TSA grave, le RC augmentait, et il était significatif pour les 1er et 2e groupes de cas.
Conclusion
Nos constatations confirment également une association entre les PNG brèves et les TSA plus graves.
Mots Clés: autisme, période de non-gravidité, analyse secondaire, données administratives, couplage des dossiers, Centre de la politique des soins de santé du Manitoba
Footnotes
Acknowledgements: This work was supported by a Secondary Analysis of Databases Operating Grant from the Canadian Institutes of Health Research (SEC 117119). We are indebted to Manitoba Education and Advanced Learning, Manitoba Family Services, and Manitoba Jobs and the Economy, as well as Health Information Management, Manitoba Health, Healthy Living and Seniors, for provision of data. The authors acknowledge the Manitoba Centre for Health Policy for use of data contained in the Population Health Research Data Repository under project # HIPC 2011/2012-37.
Disclaimer: The results and conclusions are those of the authors and no official endorsement by the Manitoba Centre for Health Policy, Manitoba Health, Healthy Living and Seniors, or other data providers is intended or should be inferred.
Conflict of Interest: None to declare.
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