A large body of prior evidence suggests that foreign-born or less-acculturated immigrants experience a lower risk of initiating smoking of tobacco cigarettes, smoking at a lower frequency and intensity, compared to U.S.-born peers or more acculturated immigrants. This evidence is consistent with a proposition that immigration-associated shifts of environmental conditions and processes help to shape smoking patterns, but threats to validity include immigration-related selection bias and possibly confounding effects of birth cohort. This dissertation research has three aims. The first is to estimate effects of immigration (into the U.S.) on initiation of cigarette smoking, with separate estimates for sex and race/ethnicity subgroups. The second is to estimate the degree to which dynamic acculturation status might affect a person’s risk/time to start of cigarette smoking, and potential subgroup variations by sex and race/ethnicity. The third aim estimates a potential indirect effect of nativity status on time-to-initiation for smoking, through peer influence and parent-child bonding.The study population for this dissertation research consisted of 7th-12th grade school-attending adolescents in the United States, with a nationally representative sample as organized for the National Longitudinal Study of Adolescent Health (ADD HEALTH). ADD HEALTH followed these participants into adulthood during a 14-year period with four in-home assessment visits. To evaluate my hypotheses, I turned to survival analysis methods, including a new approach that can be used to study mediational processes for time-to-event outcomes.The dissertation research estimates include contrasts of smoking risk experiences for adolescents before and after immigration, with evidence of immigration-associated increased risk. First, upon immigration, adolescents were more likely to start tobacco cigarette smoking, with a hazard ratio (HR) of 1.6, and a 95% confidence interval (CI) = (1.1, 2.5), as compared with similar adolescents before immigration. Post-estimation exploration disclosed a more prominent effect estimate for females (HR=3.5; 95% CI = (1.6, 7.5); smaller HR for males with p > 0.05), as well as concentration of risk for Asian females and for Hispanic females after immigration (p<0.05). Similar effect estimate was obtained for Hispanic males after immigration, but not for non-Hispanic whites or blacks. It follows that environmental shifts associated with immigration may well play an important role in shaping the differences in risk and time to initiation. Second, immigrant female adolescents with greater acculturation within the U.S. had greater risk and earlier initiation, as compared with less acculturated females (HR=1.23; 95% CI = 1.1, 1.4). Post-estimation exploration suggested concentration of this risk among Hispanic females. Third, in a contrast of foreign-born versus U.S.-born adolescents, the mediational model from survival analysis of time-to-event data suggested mediation of a nativity effect on smoking initiation via peer influence (~17%, 95% CI=(7.1, 22.1)), with no tangible intermediate pathway through strength of bonding to one’s family of origin. This dissertation research project’s evidence clarifies the degree to which youthful immigration into the U.S. might affect risk of starting to smoke tobacco cigarettes, as well as potential mechanisms. Especially for Asian and Hispanic female immigrants, possibly for Hispanic males, public health attention is needed, possibly with subgroup-targeted prevention initiatives that focus upon interpersonal processes involving peer influence and resistance skills.
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