Patterns of Drug Use, Risky Behavior, and Health Status Among Persons Who Inject Drugs Living in San Diego, California: A Latent Class Analysis

Abstract

Background: Among persons who inject drugs (PWID), polydrug use (the practice of mixing multiple drugs/alcohol sequentially or simultaneously) increases risk for HIV transmission and unintentional overdose deaths. Research has shown local drug markets influence drug use practices. However, little is known about the impact of drug mixing in markets dominated by black tar heroin and methamphetamine, such as the western United States. Methods: Data were collected through an ongoing longitudinal study examining drug use, risk behavior, and health status among PWID. Latent class analysis (LCA) was used to identify patterns of substance use (heroin, methamphetamine, prescription drugs, alcohol, and marijuana) via multiple administration routes (injecting, smoking, and swallowing). Logistic regression was used to identify behaviors and health indicators associated with drug use class. Results: The sample included 511 mostly white (51.5%) males (73.8%), with mean age of 43.5 years. Two distinct classes of drug users predominated: methamphetamine by multiple routes (51%) and heroin by injection (49%). In multivariable logistic regression, class membership was associated with age, race, and housing status. PWID who were HIV-seropositive and reported prior sexually transmitted infections had increased odds of belonging to the methamphetamine class. Those who were HCV positive and reported previous opioid overdose had an increased odds of being in the primarily heroin injection class (all P-values < .05). Conclusion: Risk behaviors and health outcomes differed between PWID who primarily inject heroin vs. those who use methamphetamine. The findings suggest that in a region where PWID mainly use black tar heroin or methamphetamine, interventions tailored to sub-populations of PWID could improve effectiveness.

Keywords :

• persons who inject drugs
• polydrug use
• latent class analysis
• tailored interventions
• San Diego
• California

THE AUTHORS

Dr. Roth, PhD, MPH, worked in a variety of community-based organizations prior to embarking on her graduate training. Across these positions, she worked to link individuals to sexually transmitted infection (STI) and HIV testing, medical care, and social services to decrease their likelihood of acquiring/transmitting communicable diseases. In September 2014, she joins the Department of Community Health and Prevention at Drexel University as Assistant Professor. In Philadelphia, she will utilize a community-engaged research approach to design and evaluate intervention studies for STIs, HIV, and drug abuse-related disparities.

Mr. Armenta, PhD(c), MPH, MA., is an epidemiologist who studies infectious disease transmission dynamics and novel methods in which persons who inject drugs distribute and inject drugs. His curent research interests include to understand emerging behaviors, how they affect disease incidence and prevalence and to develop intervention strategies to help curb the spread of disease.

Karla Wagner, Ph.D., is an Assistant Professor in the School of Community Health Sciences at the University of Nevada, Reno. She conducts mixed methods behavioral research that focuses on the prevention of negative health outcomes associated with injection drug use, especially HIV, viral hepatitis, and fatal overdose. She has worked with syringe exchange programs in New York and Los Angeles, and is involved in the development and evaluation of overdose prevention/naloxone distribution programs. Her current projects investigate the social network factors associated with HIV risk behavior among female sex workers and their drug-using male partners in Tijuana, Mexico. She earned a Master's degree in Anthropology from Northern Arizona University, and a Ph.D. in Preventive Medicine (Health Behavior Research) from the University of Southern California Keck School of Medicine.

Scott C. Roesch, Ph.D., is a professor of psychology at SDSU, where he teaches multivariate statistics at the graduate level. In addition to authoring over 100 publications, he is currently serving as an Associate Editor for Implementation Science, and has served as an Associate Editor for the journal of Health Psychology. His primary research interest is the application of novel statistical methodology (e.g., latent variable methods) to physical and mental health data.

Ricky N. Bluthenthal, Ph.D., is a Professor in the Department of Preventive Medicine and the Institute for Prevention Research at the Keck School of Medicine, University of Southern California. His current research interests include health disparities related to substance users, sexual minorities, and infectious diseases, such as HIV, hepatitis C virus, and STIs. Current studies include research on injection initiation and prevention, family-based health promotion for Latino families, and racial and ethnic differences in HIV risk and substance use among gay men. He received his doctoral degree in sociology from the University of California, Berkeley in 1998.

Mrs. Cuevas-Mota, MPH, has almost 10 years of research experience ranging from Dating Violence, Tuberculosis (TB), Physical Activity, Smoking, HIV, Hepatitis C, Injection Drug Use among high risk populations in local and binational settings. She is fluently bilingual in English and Spanish and has experience in qualitative and quantitative data collection. Her current interests include continuing to work in benefit of underserved communities, to reduce health inequities and promote healthy communities in the U.S.-México border region.

Richard S. Garfein, PhD, MPH, is a Professor in the Division of Global Public Health, Department of Medicine at UCSD. His current research interests include identifying risk factors for and developing interventions to prevent infectious diseases associated with substance abuse. Dr. Garfein has recently expanded the scope of his research to include describing tuberculosis among vulnerable populations, evaluating molecular assays for rapid detection of drug resistant TB, and developing mobile phone based interventions for improving patient adherence to anti-TB treatment. His international research and consulting activities have included Mexico, Russia, Thailand, Taiwan, Okinawa, Puerto Rico, Malawi, Sierra Leone, and Kyrgyzstan.

Notice of correction:

Changes have been made to this article since its original online publication date of October 14, 2014.

APPENDIX TABLE A1 Prevalence of weekly or more frequent drugs used by PWID in the San Diego STAHR-II Cohort, 6 months^a