PLoS One

Quantifying the association between lifetime exposures and the risk of developing a chronic disease is a recurrent challenge in epidemiology. Individual exposure trajectories are often heterogeneous and studying their associations with the risk of disease is not straightforward. We propose to use a latent class mixed model (LCMM) to identify profiles (latent classes) of exposure trajectories and estimate their association with the risk of disease. The methodology is applied to study the association between lifetime trajectories of smoking or occupational exposure to asbestos and the risk of lung cancer in males of the ICARE population-based case-control study. Asbestos exposure was assessed using a job exposure matrix. The classes of exposure trajectories were identified using two separate LCMM for smoking and asbestos, and the association between the identified classes and the risk of lung cancer was estimated in a second stage using weighted logistic regression and all subjects. A total of 2026/2610 cases/controls had complete information on both smoking and asbestos exposure, including 1938/1837 cases/controls ever smokers, and 1417/1520 cases/controls ever exposed to asbestos. The LCMM identified four latent classes of smoking trajectories which had different risks of lung cancer, all much stronger than never smokers. The most frequent class had moderate constant intensity over lifetime while the three others had either long-term, distant or recent high intensity. The latter had the strongest risk of lung cancer. We identified five classes of asbestos exposure trajectories which all had higher risk of lung cancer compared to men never occupationally exposed to asbestos, whatever the dose and the timing of exposure. The proposed approach opens new perspectives for the analyses of dose-time-response relationships between protracted exposures and the risk of developing a chronic disease, by providing a complete picture of exposure history in terms of intensity, duration, and timing of exposure

A Three-Generational Study of Risk Factors for Childhood Externalizing Behavior among African Americans and Puerto Ricans

This is the first prospective study to examine the precursors of child externalizing behavior across three generations of African Americans and Puerto Ricans. Participants comprised a community cohort of male and female African Americans and Puerto Ricans (N = 366, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\overline{X}$$\end{document} age = 29.4 years), who are part of an ongoing study of drug use and problem behaviors, and who had a child. Data were collected at four time waves, spanning the participants’ adolescence to adulthood. Questionnaires were initially self-administered in schools in East Harlem, NY, USA (time 1). Subsequently, structured interviews were conducted by trained interviewers (times 2 and 3), and self-administered via mail (time 4). The independent variables consisted of the participants’ prospective reports of their (a) relationships with their parents during adolescence, (b) depressive mood and drug use (adolescence to adulthood), (c) relationship with their oldest child between the ages of 6–13, and (d) perceptions of neighborhood crime and deterioration (in adulthood). The dependent variable was externalizing behavior in the participant’s oldest child (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\overline{X}$$\end{document} age = 9.6 years; SD = 2.0). Structural equation modeling showed that the parent–child relationship during participants’ adolescence was linked with the participants’ depressive mood and drug use which, in turn, were associated with the participants’ relationship with their own child, as well as with neighborhood crime and deterioration when participants were adults. The participants’ depressive mood, and relationship with their own child, as well as neighborhood crime and deterioration, each had a direct pathway to externalizing behavior in the participant’s child. Findings suggest that intervention programs and public policy should address parental attributes, neighborhood factors, and, especially, parenting skills, to reduce risk factors for the intergenerational transmission of externalizing behavior