摘要：Objectives. Adolescence and young adulthood (ages 18–25 years) are periods of development and change, which include experimentation with and adoption of new roles and behaviors. We investigated longitudinal trajectories of sexual risk behaviors across these time periods and how these trajectories may be different for varying demographic groups. Methods. We developed multilevel growth models of sexual risk behavior for a predominantly African American sample (n=847) that was followed for 8 years, from adolescence to young adulthood. We investigated differences in growth parameters by race/ethnicity and gender and their interactions. Results. The final model included linear and quadratic terms for both adolescence and young adulthood, indicating acceleration of sexual risk behaviors during adolescence and a peak and deceleration during young adulthood. African American males exhibited the highest rate of sexual risk behavior in ninth grade, yet had the slowest rate of growth. Compared with their White peers, African American males and females exhibited less sexual risk behavior during young adulthood. Conclusions. Our results suggest that youths of different races/ethnicities and genders exhibit varying sexual risk behavior trajectories. Adolescent sexual risk behavior may have profound health consequences, 1 which can extend into later life. 2 Adolescents may be susceptible to engagement in sexual risk behaviors such as infrequent use of condoms 3 or having multiple partners 4 because of underdeveloped decisionmaking skills. 5 Young adulthood, defined here as ages 18–25 years, is a time when youths take on new roles and responsibilities and form adult identities, 6 , 7 which may include a relationship with a significant other and changes in sexual behavior. Sexual risk behavioral patterns adopted during adolescence and young adulthood may continue throughout adulthood. It is therefore vital to understand sexual risk trajectories during adolescence and young adulthood. One problem with much of the research on sexual risk behavior in adolescence and young adulthood is that most studies are cross-sectional and consequently focus either on adolescence or adulthood. 8 Most longitudinal studies included only 2 waves of sexual risk behavior data, 9 – 13 assessed sexual risk behavior at only 1 time point, 3 , 14 , 15 did not include data that spanned both of these developmental periods, 8 investigated an overall mean level of sexual risk behavior across study waves, 16 , 17 or conducted separate analyses for each wave of data. 18 These study designs are insufficient for capturing trajectories of behavior. 19 In a multiwave study of predominantly White males that spanned adolescence and young adulthood, Capaldi et al. 16 suggested that their pattern of results showed the frequency of sexual intercourse increasing, the number of partners increasing then decreasing, and condom use decreasing, although the researchers did not test these suggestions statistically. Similarly, O’Donnell et al. 3 suggested in their 4-wave study of urban youths that frequency of sexual intercourse increases and condom use decreases during early adolescence, but they did not provide statistical tests. Longitudinal studies that include several waves of data spanning adolescence and young adulthood and that investigate and test trajectories of sexual risk behavior are lacking. It is further not clear how Capaldi et al.’s 16 suggestions may generalize to non-White or female youths or how O’Donnell et al.’s 3 results generalize to older youths. It is vital that we understand the trajectories of sexual risk behavior for different demographic groups. The consequences of sexual risk behavior, including contracting HIV/AIDS 20 and gonorrhea and syphilis, 21 for example, disproportionately affect African Americans compared with other groups. Also, compared with men, women are more likely to have asymptomatic sexually transmitted diseases, 22 and they make up an increasingly larger share of the incidence of HIV. 23 Understanding the differential trajectories of adolescent and young adult sexual risk behaviors among men and women from various races/ethnicities may help to explain these disparities. Nationally representative studies have suggested that sexual risk behaviors among youths differ by race/ethnicity and gender. In the 2003 Youth Risk Behavior Surveillance System high school survey, 24 African American students were found to be more likely to have had sexual intercourse and to report a greater number of sexual partners, yet were more likely to have used a condom during last sexual intercourse, compared with White students. In the same survey, 24 boys were found to be equally as likely to have had sexual intercourse, to report a greater number of sexual partners, and to be more likely to have used a condom during last intercourse as girls. Although the Youth Risk Behavior Surveillance System and similar studies are informative in assessing trends in adolescent sexual risk behavior across time, they do not allow us to investigate individual trajectories of behavior, which provide information about the shape of change in the behavior in the same group of individuals over time. The Youth Risk Behavior Surveillance System also does not include young adulthood. In our study, we addressed some of the shortcomings in the literature. First, we examined data over 8 years that included the period of young adulthood. Second, we employed an analytic approach—hierarchical linear modeling—that permits the study of trajectories of change over time. Finally, we investigated how trajectories of sexual risk behavior may differ by race/ethnicity and gender.
