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.

Factors Associated with Patterns of Mobile Technology use among Persons who Inject Drugs

“…To reduce potential misclassification bias, we only included MTU variables as indicators where at least 15% of participants reported their use for inclusion in the LCA. 14 …”

Prevalence and Correlates of Heroin–Methamphetamine Co-Injection Among Persons Who Inject Drugs in San Diego, California, and Tijuana, Baja California, Mexico

“…Injection drug use, a large red-light district (zona roja) attracting sex tourism, and high levels of social and economic disparities have contributed to a localized HIV epidemic in Tijuana. Given the substantial bidirectional traffic of people and goods in this region, there are significant implications for cross-border spread of unsafe injecting practices that heighten the risk of blood-borne infections, including HIV and hepatitis C. Although PWID are known to inject both heroin and methamphetamine (Darke & Hall, 1995;Garfein et al, 2013;Meacham et al, 2015;Roth et al, 2015;Rusch et al, 2009), less is known about the prevalence of and risks associated with mixed or co-injection of this depressant-stimulant combination.The present analysis examined the prevalence and correlates of heroin-methamphetamine co-injection among PWID in San Diego, California, and Tijuana, Baja California. Given the production of methamphetamine in Mexico and the limited access to healthcare and drug treatment services, we hypothesized that past-6-month prevalence of heroinmethamphetamine co-injection would be higher among PWID in Tijuana.…”

Rural and urban comparisons of polysubstance use profiles and associated injection behaviors among people who inject drugs in Puerto Rico

“…Within samples, however, we found that latent classes with a higher number of substance use combinations have higher probabilities of risky injection behavior than classes characterized by fewer substances. The rural and urban classes characterized by primarily heroin injectors had the lowest probability of risky injection behavior, echoing results from PWID in Baltimore (Kuramoto et al, 2011) and San Diego (Roth et al, 2015). Conversely, the urban class that was characterized by high injection and non-injection polysubstance use had the highest probabilities of risky injection behavior, findings supportive of research among various samples of PWID (Harrell et al, 2012).…”

“…Response options ranged from (0) never to (9) four or more times per day. To differentiate between habitual use rather than episodic use (Roth et al, 2015), we dichotomized each item into (0) less than weekly use and (1) weekly or more use.…”

“…LCA is a statistical method which aims to identify latent subgroups of individuals who share similar profiles on a set of observed variables (Collins and Lanza, 2013), and has recently been used to characterize polysubstance use among PWID outside of Puerto Rico (Betts et al, 2016; Hopfer et al, 2014; Meacham et al, 2015; Roth et al, 2015). LCA, however, has not been used previously to compare urban and rural PWID.…”