SMOKING Educational attainment and cigarette smoking: a causal association?y

Results In the full sample of participants, regression analyses adjusting for multiple childhood factors (including socioeconomic status, IQ, behavioural problems, and medical conditions) indicated that the number of pack-years smoked was higher among individuals with less than high school education [rate ratio (RR)1⁄4 1.58, confidence interval (CI)1⁄4 1.31, 1.91]. However, in the sibling fixed effects analysis the RR was 1.23 (CI1⁄4 0.80, 1.93). Similarly, adjusted models estimated in the full sample showed that individuals with less than high school education had fewer short-term (RR1⁄4 0.40; CI1⁄4 0.23, 0.69) and long-term (RR1⁄4 0.59; CI1⁄4 0.42, 0.83) quit attempts, and were less likely to quit smoking (odds ratio1⁄4 0.34; CI1⁄4 0.19, 0.62). The effects of education on quitting smoking were attenuated in the sibling fixed effects models that controlled for familial vulnerability to smoking.