Database: the National Longitudinal Study of Adolescent to Adult Health

This study was a retrospective cross-sectional study, using Wave I data of the National Longitudinal Study of Adolescent to Adult Health (Add Health).40,41 Add Health is a longitudinal study of the nationally representative US adolescents from 1994 to 2008 with four waves of interviews. A sample of 80 high schools and 52 middle schools was selected from the US with unequal probabilities of selection. Incorporating systematic sampling methods and implicit stratification assured that the sample was nationally representative with respect to region, urbanicity, school size, school type, and ethnicity. Add Health Wave I, including an in-school questionnaire and in-home interviews, was conducted when respondents were in grades 7–12 in 1994–1995. Add Health Wave II, conducted in 1996, covered the same questions of in-home interviews of Wave I and additional details, such as sun exposure and nutrition. Therefore, Waves I and II gathered adolescents’ social and demographic information, as well as behavior decision-making. Add Health Wave III was collected in years 2001 and 2002 measuring the outcomes of decision-making, such as relationships, sexual experience, mental health, and criminal records. Add Health Wave IV collected in years 2008 and 2009, gathered longitudinal information on respondents’ social, economic, and health status, and involvement of criminal justice system. All waves of Add Health were linked with pseudo identification; respondents were not identified through any information of the database. The target population of this study was African-American respondents in Wave I of Add Health.