Latent Growth Curve Model Evaluation of Illicit Substance and Tobacco Use among Young Adults in Cumberland County, North Carolina
Authors: Mongkuo Maurice Y 
Published: January 2021

Aim: Young adulthood is a period when individuals experiment health risk substances such as illicit substance and tobacco use that may predispose them to sexually transmitted diseases. Minority young adults living in HIV prevalent urban communities are notably more likely to engage in these behaviors. In the United States, minority young adults over-represented with HIV infection. To resolve this problem, the United States Congress has invested over $100million in grants. In the United States, few studies have examined illicit substance and tobacco use among this vulnerable population. This study aimed to evaluate the impact of a comprehensive HIV prevention program (CIHPP) on illicit substance and tobacco use among minority young adults living in a high prevalence of HIV infection urban community. Methods: The data of illicit substance and tobacco use was collected using a survey of a random sample of minority young adults who participated in the CIHPP. for12-months. Change in illicit substance and tobacco use during 24 months of minority young adults' participation in CIHPP was recorded. The data was analyzed using the latent growth curve (LGC) model within the framework of the structural equation modeling procedure. The evaluation included the change in the intercept and slope of the Mean, Variance, covariance, and predictor variable in three waves for 24months. Result: The average score for illegal substance use of 5.411 decreased significantly over the 24months. Young adults exhibited a low rate of increase in their illicit use substance over the 24months. This finding indicates that the CIHPP was effective in decreasing the substance use of young adults under study. There were significant inter individual differences in the original score of illicit substance use between the young adults at the beginning of the implementation of the CIHPP and its change over time, as the as the minority young adult progressed from the beginning of the CIHPP intervention through the 24 months. Using gender as a predictor of change showed no difference between male and female young adults. For tobacco use, the average score for tobacco (16.631) decreased significantly over the three 24months. There was no meaningful difference between minority young adult males and minority young adult females in illicit substances use at the beginning of CIHPP. However, during CIHPP intervention, minority young adult’s males had an increase in the rate of change in tobacco use than minority young adult females. The mean estimate for tobacco use indicates that the average score for tobacco use increased significantly over the three 12-months periods. The covariance between the intercept and slope factor for tobacco use was statistically significant. Minority young adult males exhibited a higher rate of tobacco use than their female counterparts over the 24 months. This finding suggests that the Comprehensive, integrated HIV prevention program was not effective in decreasing the tobacco use of the minority young adults studied, The variance estimate related 2 Annals of Immunology & Immunotherapy Mongkuo MY, et al. Latent Growth Curve Model Evaluation of Illicit Substance and Tobacco Use among Young Adults in Cumberland County, North Carolina. Ann Immunol Immunother 2020, 2(2): 000124. Copyright© Mongkuo MY, et al. to the intercept and slope for tobacco use is statistically significant (p=.001) suggesting that there were vast inter-individual differences both at the beginning of CIHPP and the rate of change of tobacco use between the minority young adults at the beginning of the implementation of the CIHPP and its rate of change over time, as the young adult progressed from the beginning of the CIHPP intervention through the 24months. Such evidence provides sturdy support for further investigation of variability or heterogeneity related to the growth trajectory. Specifically, the incorporation of time-invariant of change into the model can explain the young adults' tobacco use variability. This incorporation involves testing the latent growth curve model with the demographic or static variable as a time-invariant predictor of change. This study incorporated gender in the LGC model as a predictor of change. The prediction module with gender as predictor found that there was no meaningful difference in illicit substance and tobacco use between minority young adult males and females.