Question

A case-control study examined the association between maternal smoking during pregnancy and ADHD among children. The investigators decided to match the cases and controls by the mother’s level of education. What is the effect of matching in this study? Choose the best answer.

Answer 1

Several approaches used to control different methods and cohort provides strong evidence. There were 3 different negative control approaches control design was used parents smoking during pregnancy, grandmother smoking when mother was pregnant, maternal smoking during a previous pregnancy.
Cohort study includes more than 1,11,000 children, 95,000 mothers, and 75,000 fathers. the study excluded children with congenital malformations and with multiple births from the analysis.
Sibling control analysis added in the statistical analysis performed twice with and without imputations on the 5 year ADHD controlled for maternal parity, age and child's birth year. The total sample included 104846 children with 2035 children with ADHD. Results show <1% were 7 years and lesser and 4.3% among 14years old. There is a low ratio of ADHD in young children. In the null hypothesis the maternal smoking during pregnancy equally associated with offspring ADHD.
Sibling analysis associated with the mother reported ADHD symptoms associated with smoking during pregnancy. strongly related to offspring birth weight in negative controls. There was strong evidence that maternal smoking and offspring birth weight in siblings discordant for maternal smoking.