Is drug insurance status an effect modifier in epidemiologic database studies? The case of maternal XXXX and major @entity600 .

@entity1 @entity565 @entity748 @entity600
BACKGROUND: Our previous work on the association between maternal @entity565 and @entity600 was based on cohorts formed by @entity1 with public drug insurance, i.e., over-represented by @entity1 with lower socioeconomic status, questioning the generalizability of our findings. This study aimed to evaluate whether or not drug insurance status, as a proxy of socioeconomic status, is an effect modifier for the association between maternal @entity565 and major @entity600 . METHODS: A cohort of 36,587 pregnancies from @entity748 @entity1 and 198,935 pregnancies from nonasthmatic @entity1 selected independently of their drug insurance status was reconstructed with Qu  bec administrative databases (1998-2009). Asthmatic @entity1 were identified using a validated case definition of @entity565 . Cases of major @entity600 were identified using diagnostic codes recorded in the hospitalization database. Drug insurance status at the beginning of pregnancy was classified into three groups: publicly insured with social welfare, publicly insured without social welfare, and privately insured. Adjusted odds ratios were estimated with generalized estimation equations, including an interaction term between maternal @entity565 and drug insurance status. RESULTS: The prevalence of @entity600 was 6.8% among @entity748 @entity1 and 5.8% among nonasthmatics. The impact of @entity565 on the prevalence of @entity600 was significantly greater in @entity1 publicly insured with social welfare (odds ratio   =   1.42; 95% confidence interval, 1.25-1.61) than in the other two groups ([odds ratio   =   1.10; 1.00-1.21] in the publicly insured without social welfare and [odds ratio   =   1.13; 1.07-1.20] in the privately insured group). CONCLUSION: The increased risk of major @entity600 associated with @entity565 was significantly higher among pregnant @entity1 publicly insured with social welfare than among those privately insured. As a result of this effect modification by drug insurance status, findings from Qu  bec observational studies using databases mainly formed of @entity1 publicly insured with social welfare may not be generalized to the entire population.
