title: The Impact of Different Case Ascertainment Definitions on the Prevalence of Major Congenital Malformations and their Association with Asthma During Pregnancy.
abstract: Objectives To compare the prevalence of major malformations using different case ascertainment definitions and to evaluate their impact on maternal asthma-major malformations association. Methods A cohort of pregnancies with and without asthma between 1990 and 2010 was formed. We used two classification methods: the Two step Congenital Malformation Classification (TCMC) and the Canadian Congenital Anomalies Surveillance System (CCASS). Within each method, three case definitions were compared: (1) ≥1 diagnosis in the hospital database; (2) ≥1 diagnosis in the hospital database or ≥2 in the medical claims; and (3) ≥1 diagnosis in the hospital database or ≥1 in the medical claims. We calculated the prevalence of major malformations and adjusted odds ratios (aORs) for maternal asthma association. Results Of 467,946 pregnancies, 12.3 % were with active asthma. The prevalence estimates were: TCMC 5.10-7.08 % and CCASS 7.03-10.57 %. Asthma-major malformations association was weaker with the CCASS (aOR 1.14-1.20) versus TCMC (aOR 1.22-1.26). Discussion The case ascertainment definitions with ≥1 hospitalization are likely to be the most reliable in similar administrative databases. The case ascertainment definition had a considerable impact on the prevalence of major malformations, but hardly influenced the aORs. Future studies should formally assess the validity of the case ascertainment definitions and allow generalizability to other maternal exposures.
authors.affiliation: Faculté de pharmacie, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC, H3C 3J7, Canada.|Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, QC, H4J 1C5, Canada.
authors.forename: Sherif
authors.initials: S
authors.lastname: Eltonsy
authors.affiliation: Faculté de pharmacie, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC, H3C 3J7, Canada.|Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, QC, H4J 1C5, Canada.
authors.forename: Amelie
authors.initials: A
authors.lastname: Forget
authors.affiliation: Faculté de pharmacie, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC, H3C 3J7, Canada. lucie.blais@umontreal.ca.|Hôpital du Sacré-Cœur de Montréal, 5400, boul. Gouin Ouest, Montréal, QC, H4J 1C5, Canada. lucie.blais@umontreal.ca.
authors.forename: Lucie
authors.initials: L
authors.lastname: Blais
mesh_terms: D000293:Adolescent; D000328:Adult; D018927:Anti-Asthmatic Agents / Q000009:adverse effects / Q000627:therapeutic use; D001249:Asthma / Q000453:epidemiology*; D015331:Cohort Studies; D000013:Congenital Abnormalities / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D018811:Maternal Exposure / Q000009:adverse effects; D016017:Odds Ratio; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D015995:Prevalence; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors
chemical_list: D018927:Anti-Asthmatic Agents
keywords: Administrative databases; Asthma; Case definitions; Congenital malformations; Pregnancy