EPI 201 Lab41. Voge GA, Katusic SK, Quin R, and Juhn YJ. (2015). Risk of asthma in late preterm infants: A propensity score approach. Journal of Allergy and Clinical Immunology: In Practice, Äi0In Press. The Rochester Birth Cohort is a retrospective, closed cohort of all children born from 1976 through 1982 in Rochester, Minnesota. Using this cohort, investigators were interested in the association between preterm vs full term live birth and the risk of developing asthma by age 7. Below is hypothetical data for the association between preterm vs full term live birth and asthma during the 7-year study period stratified by maternal smoking during pregnancy. No participants were lost to follow-up. smokePreFullBA23145168No BA90976106611311211234No smPreFullBA9159168No BA1724405457718145644745a.Calculate the cumulative incidence ratio for the crude associationbetween preterm vs. full term birth and asthma in this cohort?Interpret your result.2.035 over the 7-year studyperiod.PreFullBA32304336No BA2625381564329456855979CIR = (32/294) / (304/5685) =
b. The authors were concerned about confounding by maternalsmoking during pregnancy. What are the properties maternalsmoking must have to be confounder?