Drug use practices among MDMA/ecstasy users in Ohio: a latent class analysis

Association between non-injection drug use and hepatitis C infection among HIV-negative men who have sex with men

BACKGROUND

Prior research predominantly examined the association between HIV-positive men who have sex with men (MSM) or those using injection drugs and hepatitis C virus (HCV) infection. However, limited attention has been given to understanding the association among HIV-negative MSM who do not inject drugs. This gap leaves apportion of the population unexamined, potentially overlooking important factor that may contribute to the transmission and prevalence of HCV. This study aims to investigate the relationship between non-injection drug use and HCV infection in this population.

METHODS

In this cross-sectional study, we analyzed data on 118 MSM who reported use of non-injection drugs. The participants were recruited from two inner-city communities in Houston, TX, between 2004 and 2007 and were negative for both HIV and hepatitis B virus infection. Latent class analysis (LCA) was used to identify drug use latent classes. Multinomial logistic regression analysis was used to evaluate the association between drug use latent class and HCV infection.

RESULTS

Four distinct latent classes of drug use were identified: class 1, persons ≥ 42 years of age who used only crack cocaine; class 2, persons approximately 42 years of age who used > 2 drugs; class 3, persons < 42 years of age who used > 5 drugs; and class 4, persons ≥ 42 years of age who used > 6 drugs. Class 4 was significantly associated with HCV infection. The odds of HCV infection in members of class 4 was 17 times higher than in class 2 members (adjusted odds ratio [aOR] = 16.9, 95% confidence interval [CI]: 1.4-205.4) and almost 22 times higher than in class 3 members (aOR = 21.8, 95% CI: 1.5-322.8).

CONCLUSIONS

Among MSM with non-injection drug use, the subgroup of individuals who were ≥ 42 years of age and used multiple drugs (including heroin, speedball, methamphetamine, crack cocaine, and marijuana) had a high probability of HCV infection. Public health and education programs, as well as drug treatment and rehabilitation programs, should be developed for this high-risk subgroup of individuals to prevent HCV acquisition and transmission.

Differential risks of syringe service program participants in Central Ohio: a latent class analysis

BACKGROUND

Significant heterogeneity exists among people who use drugs (PWUD). We identify distinct profiles of syringe service program (SSP) clients to (a) evaluate differential risk factors across subgroups and (b) inform harm reduction programming.

METHODS

Latent class analysis (LCA) was applied to identify subgroups of participants (N = 3418) in a SSP in Columbus, Ohio, from 2019 to 2021. Demographics (age, sex, race/ethnicity, sexual orientation, housing status) and drug use characteristics (substance[s] used, syringe gauge, needle length, using alone, mixing drugs, sharing supplies, reducing use, self-reported perceptions on the impact of use, and treatment/support resources) were used as indicators to define latent classes. A five-class LCA model was developed, and logistic regression was then employed to compare risk factors at program initiation and at follow-up visits between latent classes.

RESULTS

Five latent classes were identified: (1) heterosexual males using opioids/stimulants with housing instability and limited resources for treatment/support (16.1%), (2) heterosexual individuals using opioids with stable housing and resources for treatment/support (33.1%), (3) individuals using methamphetamine (12.4%), (4) young white individuals using opioids/methamphetamine (20.5%), and (5) females using opioids/cocaine (17.9%). Class 2 served as the reference group for logistic regression models, and at the time of entry, class 1 was more likely to report history of substance use treatment, overdose, HCV, sharing supplies, and mixing drugs, with persistently higher odds of sharing supplies and mixing drugs at follow-up. Class 3 was more likely to report history of overdose, sharing supplies, and mixing drugs, but outcomes at follow-up were comparable. Class 4 was the least likely to report history of overdose, HCV, and mixing drugs, but the most likely to report HIV. Class 5 was more likely to report history of substance use treatment, overdose, HCV, sharing supplies, and mixing drugs at entry, and higher reports of accessing substance use treatment and testing positive for HCV persisted at follow-up.

CONCLUSIONS

Considerable heterogeneity exists among PWUD, leading to differential risk factors that may persist throughout engagement in harm reduction services. LCA can identify distinct profiles of PWUD accessing services to tailor interventions that address risks, improve outcomes, and mitigate disparities.

Evaluating the Quality of Classification in Mixture Model Simulations

The purpose of this study was to evaluate the degree of classification quality in the basic latent class model when covariates are either included or are not included in the model. To accomplish this task, Monte Carlo simulations were conducted in which the results of models with and without a covariate were compared. Based on these simulations, it was determined that models without a covariate better predicted the number of classes. These findings in general supported the use of the popular three-step approach; with its quality of classification determined to be more than 70% under various conditions of covariate effect, sample size, and quality of indicators. In light of these findings, the practical utility of evaluating classification quality is discussed relative to issues that applied researchers need to carefully consider when applying latent class models.

Theta and Alpha Oscillatory Activity During Working Memory Maintenance in Long-Term Cannabis Users: The Importance of the Polydrug Use Context

Background: Impairments in various subdomains of memory have been associated with chronic cannabis use, but less is known about their neural underpinnings, especially in the domain of the brain's oscillatory activity. Aims: To investigate neural oscillatory activity supporting working memory (WM) in regular cannabis users and non-using controls. We focused our analyses on frontal midline theta and posterior alpha asymmetry as oscillatory fingerprints for the WM's maintenance process. Methods: 30 non-using controls (CG) and 57 regular cannabis users-27 exclusive cannabis users (CU) and 30 polydrug cannabis users (PU) completed a Sternberg modified WM task with a concurrent electroencephalography recording. Theta, alpha and beta frequency bands were examined during WM maintenance. Results: When compared to non-using controls, the PU group displayed increased frontal midline theta (FMT) power during WM maintenance, which was positively correlated with RT. The posterior alpha asymmetry during the maintenance phase, on the other hand, was negatively correlated with RT in the CU group. WM performance did not differ between groups. Conclusions: Both groups of cannabis users (CU and PU), when compared to the control group, displayed differences in oscillatory activity during WM maintenance, unique for each group (in CU posterior alpha and in PU FMT correlated with performance). We interpret those differences as a reflection of compensatory strategies, as there were no differences between groups in task performance. Understanding the psychophysiological processes in regular cannabis users may provide insight on how chronic use may affect neural networks underlying cognitive processes, however, a polydrug use context (i.e., combining cannabis with other illegal substances) seems to be an important factor.

Appropriate analyses of bimodal substance use frequency outcomes: a mixture model approach

Background: In addiction research, outcome measures are often characterized by bimodal distributions. One mode can be for individuals with low substance use and the other mode for individuals with high substance use. Applying standard statistical procedures to bimodal data may result in invalid inference. Mixture models are appropriate for bimodal data because they assume that the sampled population is composed of several underlying subpopulations.Objectives: To introduce a novel mixture modeling approach to analyze bimodal substance use frequency data.Methods: We reviewed existing models used to analyze substance use frequency outcomes and developed multiple alternative variants of a finite mixture model. We applied all methods to data from a randomized controlled study in which 30-day alcohol abstinence was the primary outcome. Study data included 73 individuals (38 men and 35 women). Models were implemented in the software packages SAS, Stata, and Stan.Results: Shortcomings of existing approaches include: 1) inability to model outcomes with multiple modes, 2) invalid statistical inferences, including anti-conservative p-values, 3) sensitivity of results to the arbitrary choice to model days of substance use versus days of substance abstention, and 4) generation of predictions outside the range of common substance use frequency outcomes. Our mixture model variants avoided all of these shortcomings.Conclusions: Standard models of substance use frequency outcomes can be problematic, sometimes overstating treatment effectiveness. The mixture models developed improve the analysis of bimodal substance use frequency.

Not Just a Pot: Visual Episodic Memory in Cannabis Users and Polydrug Cannabis Users: ROC and ERP Preliminary Investigation

Background While research has consistently identified an association between long-term cannabis use and memory impairments, few studies have examined this relationship in a polydrug context (i.e., when combining cannabis with other substances). Aims: In this preliminary study, we used event-related potentials to examine the recognition process in a visual episodic memory task in cannabis users (CU) and cannabis polydrug users (PU). We hypothesized that CU and PU will have both-behavioral and psychophysiological-indicators of memory processes affected, compared to matched non-using controls with the PU expressing more severe changes. Methods 29 non-using controls (CG), 24 CU and 27 PU were enrolled into the study. All participants completed a visual learning recognition task while brain electrical activity was recorded. Event-related potentials were calculated for familiar (old) and new images from a signal recorded during a subsequent recognition test. We used receiver operating characteristic curves for behavioral data analysis. Results The groups did not differ in memory performance based on receiver operating characteristic method in accuracy and discriminability indicators nor mean reaction times for old/new images. The frontal old/new effect expected from prior research was observed for all participants, while a parietal old/new effect was not observed. While, the significant differences in the late parietal component (LPC) amplitude was observed between CG and PU but not between CG and CU nor CU and PU. Linear regression analysis was used to examine the mean amplitude of the LPC component as a predictor of memory performance accuracy indicator. LPC amplitude predicts recognition accuracy only in the CG. Conclusion The results showed alterations in recognition memory processing in CU and PU groups compared to CG, which were not manifested on the behavioral level, and were the most prominent in cannabis polydrug users. We interpret it as a manifestation of the cumulative effect of multiple drug usage in the PU group.

Unintentional drug overdose: Is more frequent use of non-prescribed buprenorphine associated with lower risk of overdose?

BACKGROUND

Unintentional drug overdoses have reached epidemic levels in the U.S. This study tests the hypothesis that people who have used non-prescribed buprenorphine more frequently in the past six months were less likely to experience a drug overdose during that same time period.

METHODS

Participants age 18 years or older with opioid use disorder who reported use of non-prescribed buprenorphine in the last six months were recruited from the Dayton, Ohio, area using a combination of targeted and modified respondent-driven sampling. Participants completed a structured interview, including six-month timeline follow-back, after informed consent. Logistic regression was used to test the association between (log-transformed) frequency of non-prescribed buprenorphine use and overdose in the previous six months, adjusted for confounding due to sex, homelessness, incarceration, substance use treatment, previous overdose, heroin/fentanyl injection, psychiatric comorbidity, and (log-transformed) frequencies of other (non-opioid) drug use.

RESULTS

Almost 89% of 356 participants were white, 50.3% were male, and 78.1% had high school or greater education. Over 27% (n = 98) reported experiencing an overdose in the past six months. After adjusting for confounding, greater frequency of non-prescribed buprenorphine use was significantly associated with lower risk of overdose (AOR = 0.81, 95% CI = 0.66, 0.98; p = .0286). Experiencing an overdose more than six months ago (AOR = 2.19, 95% CI = 1.24, 3.97); injection as the most common route of administration of heroin/fentanyl (AOR = 2.49, 95% CI = 1.36, 4.71); and frequency of methamphetamine use (AOR = 1.13, 95% CI = 1.02, 1.27) were strongly associated with increased risk of recent overdose in multivariable analysis.

DISCUSSION

The findings support our hypothesis that higher frequency of non-prescribed buprenorphine use is associated with lower risk of drug overdose, a potential harm reduction consequence of diversion. Improving the availability of buprenorphine though standard substance use disorder treatment, primary care, and other innovative methods is urgently needed.

Methamphetamine Use and Its Correlates among Individuals with Opioid Use Disorder in a Midwestern U.S. City

Background: U.S. is experiencing a surging trend of methamphetamine use among individuals who use opioids. More research is needed to characterize this emerging "twin epidemic." Objectives: The study aims to identify social and behavioral characteristics associated with methamphetamine use among individuals with opioid use disorder (OUD) in the Dayton, Ohio, area, an epicenter of the opioid crisis and an emerging frontier of methamphetamine epidemic. Methods: 357 adult individuals with current OUD were recruited using targeted and respondent-driven sampling. Structured interviews collected information on social and drug use characteristics. Multivariable Logistic Regression was used to identify characteristics associated with the past 6-month use of methamphetamine. Results: 49.7% were female, and 88.8% were non-Hispanic whites. 55.6% used methamphetamine in the past 6-months, and 84.9% reported first use of methamphetamine after initiation of illicit opioids. Methamphetamine use was associated with homelessness (aOR = 2.46, p = .0001), lifetime history of diverted pharmaceutical stimulant use (aOR = 2.97, p < .001), injection route of heroin/fentanyl use (aOR = 1.89, p = .03), preference for fentanyl over heroin (aOR = 1.82, p = .048), lifetime history of extended-release injectable naltrexone (Vivitrol)-based treatment (aOR = 2.89, p = .003), and more frequent marijuana use (aOR = 1.26, p = .04). Discussion: The findings point to the complexity of motivational and behavioral pathways associated with methamphetamine and opioid co-use, ranging from self-treatment and substitution behaviors, attempts to endure homelessness, and greater risk taking to experience euphoria. More research is needed to understand the causal relationships and the association between methamphetamine and Vivitrol use. Public health responses to the opioid crisis need to be urgently expanded to address the growing epidemic of methamphetamine use.

Patterns of non-prescribed buprenorphine and other opioid use among individuals with opioid use disorder: A latent class analysis

AIM

Non-prescribed buprenorphine (NPB) use increased in the US. This study aims to characterize heterogeneity in patterns of NPB and other opioid use among individuals with current opioid use disorder.

METHODS

The study recruited 356 participants in Dayton (Montgomery County), Ohio, area in 2017-2018 using targeted and Respondent Driven Sampling. Participants met the following criteria: 1) 18 years or older, 2) current moderate/severe opioid use disorder (DSM-5), 3) past 6-month NPB use. Latent class analysis (LCA) was conducted to identify subgroups based on past 6-month (days of NPB and heroin/fentanyl use; use of NPB to get high; use of non-prescribed and prescribed pharmaceutical opioids; participation in formal treatment) and lifetime (years since first NPB and other illicit opioid use) characteristics. Selected auxiliary variables were compared across classes using Asparouhov and Muthén's 3-step approach.

RESULTS

49.7% were female, and 88.8% were non-Hispanic whites. 89% used NPB to self-treat withdrawal. LCA resulted in three classes: "Heavy Heroin/Fentanyl Use" (61%), "More Formal Treatment Use" (29%) and "Intense NPB Use" (10%). After adjusting for multiple testing, the following past 6-month variables differed significantly between classes: injection as a primary route of heroin/fentanyl administration (p < 0.001), cocaine use (p = 0.044), unintentional drug overdose (p = 0.023), and homelessness (p = 0.044), with the "Intense NPB Use" class having the lowest prevalences.

CONCLUSION

Predominance of self-treatment goals and the association between more intense NPB use and lower risks of adverse consequences suggest potential harm minimization benefits of NPB use. More research is needed to understand consequences of NPB use over time.

Heterogeneity in the Co-occurrence of Substance Use and Posttraumatic Stress Disorder: A Latent Class Analysis Approach

Objective: Posttraumatic stress disorder (PTSD) often co-occurs with substance use (SU). Although there has been independent research on subgroups of participants based on their PTSD or SU responses, rarely are PTSD-SU typologies examined consistent with a precision medicine approach (and corresponding person-centered statistical approaches). The current study examined the nature and construct validity (covariates of depression, physical aggression, verbal aggression, anger, hostility, reckless and self-destructive behaviors [RSDB]) of the best-fitting latent class solution in categorizing participants based on PTSD (PTSD Checklist for DSM-5) and alcohol/drug use responses (Alcohol Use and Disorders Identification Test Alcohol Consumption Questions, Drug Abuse Screening Test). Methods: The sample included 375 trauma-exposed participants recruited from Amazon's Mechanical Turk online labor market. Results: Latent class analyses indicated an optimal three-class solution (low PTSD/SU, moderate PTSD/drug and high alcohol, and high PTSD/SU). Multinomial logistic regressions indicated that depression (OR = 1.22) and frequency of RSDBs (OR = 1.20) were significant predictors of the moderate PTSD/drug and high alcohol class versus the low PTSD/SU class. Depression (OR = 1.55) and frequency of RSDBs (OR = 1.19) were significant predictors of the high PTSD/SU class versus the low PTSD/SU class. Only depression (OR = 1.27) was a significant predictor of the high PTSD/SU class versus the moderate PTSD/drug and high alcohol class. Conclusions: Results provide construct validity support for three meaningful latent classes with unique relations with depression and RSDBs. These findings improve our understanding of heterogeneous PTSD-SU comorbidity patterns and highlight acknowledgment of such subtyping (subgrouping) in considering differential treatment options, treatment effectiveness, and resource allocation.

A latent class analysis of alcohol and drug use immediately before or during sex among women

BACKGROUND

Alcohol and drug use by women is related to high-risk sexual practices and protective behaviors.

OBJECTIVES

To determine sexual risk and protective behaviors using information about women's drug use immediately before or during sex.

METHODS

Latent class analysis using PROC LCA in SAS software was used to determine classes of women using both past 30-day drug use and before or during sex. Participants were recruited from a community-based research site located in a low socio-economic area of Los Angeles County and completed the Risk Behavior Assessment, which elicits information on drug and sex risk behaviors.

RESULTS

The Risk Behavior Assessment and HIV and sexually transmitted infections testing was obtained on 812 women. Five distinct groups were identified by PROC LCA: An Abstinent group comprised of 26% of participants; an Alcohol and Marijuana group (16%); an Amphetamine group (11%); a No Sex-with-Alcohol group (37%); and a Poly Drug group (11%). Multinomial logistic regression revealed that sexual behaviors and condom use were different across the five groups: The Alcohol and Marijuana group had a higher odds of vaginal intercourse, while the No Sex-with-Alcohol group was most likely to use condoms for vaginal intercourse. The Poly Drug group had the highest risk for anal intercourse while the Amphetamine and Poly Drug groups had high proportions of women with injection-drug using and men-who-have-sex-with-men sexual partners.

CONCLUSION

Identifying women based on drug use immediately before or during sex can help providers understand prevention and risk-reduction practices and interventions for drug-using women.

Latent Class Analysis of HIV Risk Behaviors Among Russian Women at Risk for Alcohol-Exposed Pregnancies

The number of HIV cases attributed to heterosexual contact and the proportion of women among HIV positive individuals has increased worldwide. Russia is a country with the highest rates of newly diagnosed HIV infections in the region, and the infection spreads beyond traditional risk groups. While young women are affected disproportionately, knowledge of HIV risk behaviors in women in the general population remains limited. The objectives of this study were to identify patterns of behaviors that place women of childbearing age at high risk for HIV transmission and determine whether socio-demographic characteristics and alcohol use are predictive of the risk pattern. A total of 708 non-pregnant women, aged between 18 and 44 years, who were at risk for an alcohol-exposed pregnancy were enrolled in two regions in Russia. Participants completed a structured interview focused on HIV risk behaviors, including risky sexual behavior and alcohol and drug use. Latent class analysis was utilized to examine associations between HIV risk and other demographic and alcohol use characteristics and to identify patterns of risk among women. Three classes were identified. 34.93% of participants were at high risk, combining their risk behaviors, e.g., having multiple sexual partners, with high partner's risk associated with partner's drug use (class I). Despite reporting self-perceived risk for HIV/STI, this class of participants was unlikely to utilize adequate protection (i.e., condom use). The second high risk class included 13.19% of participants who combined their risky sexual behaviors, i.e., multiple sexual partners and having STDs, with partner's risk that included partner's imprisonment and partner's sex with other women (class II). Participants in this class were likely to utilize protection/condoms. Finally, 51.88% of participants were at lower risk, which was associated primarily with their partners' risk, and these participants utilized protection (class III). The odds of being in class I compared with class III were 3.3 (95% CI [1.06, 10.38]) times higher for those women who had Alcohol Use Disorders Identification Test scores ≥ 8 than those who had lower scores, and were 3.9 (95% CI [1.69, 8.97]) times higher for those who used alcohol before sex than those who did not. In addition, women who drank more days per week were 1.36 times more likely to be in class II than in class III. The study informs prevention by identifying specific population groups and targets for interventions. Alcohol use is a significant predictor and an overarching factor of HIV risk in women. Since at-risk drinking is common among young Russian women, alcohol risk reduction should be an essential component of HIV prevention efforts.

Cannabis and psychosis: the impact of polydrug use

Purpose

While research has consistently identified an association between cannabis use and psychosis, few studies have examined this relationship in a polydrug context (i.e. combining cannabis with other illicit substances). The paper aims to discuss this issue.

Design/methodology/approach

The present study sought to examine the association between recreational drug use (cannabis only vs polydrug) and psychotic disorders. Analysis was conducted on a large, representative survey of young Danish people aged 24 (n=4,718). Participants completed self-report measures of lifetime drug use and this information was linked to the Danish psychiatric registry system.

Findings

Multivariate binary logistic regression analysis was used to examine the association between drug use (no drug use, cannabis only, cannabis and other drug) and ICD-10 psychotic disorders, while controlling for gender and parental history of psychosis. Compared with no drug use, the use of cannabis only did not increase the risk of psychosis while the odds ratio for cannabis and other drug were statistically significant.

Research limitations/implications

Psychosis risk may be associated with the cumulative effect of polydrug use.

Practical implications

Cannabis use may be a proxy for other drug use in research studies.

Originality/value

This study is innovative as it uses linked self-report and administrative data for a large sample. Administrative data were used to as an objective mental health status indicator.

A behavioral typology of opioid overdose risk behaviors among recent veterans in New York City

Objective

To identify meaningful classes of opioid-using military veterans in terms of self-reported opioid overdose risk behaviors.

Method

The study recruited a sample of 218 military veterans in the NYC area who were discharged from active duty service after September 11, 2001 and reported past-month opioid use. Survey data including measures of mental health, social stressors, substance use, and opioid-related overdose risk behaviors were analyzed using Latent Class Analysis (LCA).

Results

A five group solution had excellent fit scores and interpretability. Factor analysis confirmed the existence of two major dimensions of variation: non-adherence and heroin use. The five groups included lower-risk prescription opioid users, non-adherent prescription opioid users and heroin users. The non-adherent prescription opioid users and heroin user classes were both further subdivided into “occasional” and “regular” use categories. In addition to endorsing a greater number of overdose risk behaviors, users in the regular use classes were more likely to screen positive for alcohol and substance use disorders, reported greater self-medicating opioid use to relieve anxiety, reported greater problems with physical pain, were more likely to have had mental health, alcohol and drug treatment, and were less likely to be employed or in school. Heroin users also were less likely to report stable housing.

Conclusions

Findings indicate that opioid overdose risk classes are grounded in contextual factors related to experiences of psychological, physiological, and social adjustment pain and distress which should be addressed in tailored interventions targeting opioid users’ unique constellations of risk behaviors and comorbid conditions.

Distinguishing subpopulations of marijuana users with latent profile analysis

BACKGROUND

Although marijuana is the most commonly used illicit drug in the United States, little is known about the effects of typical marijuana use patterns and whether there are distinct subgroups of marijuana users.

METHODS

The present study used latent profile analysis to determine the number of distinct subgroups of marijuana users in a large sample of college students (n=2129 past month marijuana users across 11 universities). We also examined how these distinct groups differ on several putative risk/protective factors (e.g., personality traits, perceptions of marijuana, and motives for using marijuana).

RESULTS

Using the Lo-Mendell-Rubin Likelihood Ratio Test, we identified four latent classes with the largest class consisting of infrequent marijuana users, and three other classes demonstrating increasingly frequent use and more negative consequences with the most severe class being the smallest class. We found the largest between-class differences (i.e., distinctions across classes) to be on identification with being a marijuana user and use of protective behavioral strategies (PBS), such that the heavier user classes showed higher identification with marijuana users and lower use of PBS.

CONCLUSIONS

Our findings demonstrate that college student marijuana users are a heterogeneous group with different profiles of risk/protective factors and that those who use marijuana a few times per month are different from those who are near-daily or daily users. Our findings also serve as a call to action for the field to consider examining identification with being a marijuana user and the use of PBS in future marijuana studies.

Substance Use Patterns Among Adolescents in Europe: A Latent Class Analysis

BACKGROUND

Several researchers have investigated substance use patterns using a latent class analysis; however, hardly no studies exist on substance use patterns across countries.

OBJECTIVES

Adolescent substance use patterns, demographic factors, and international differences in the prevalence of substance use patterns were explored.

METHODS

Data from 25 European countries were used to identify patterns of adolescent (12-16 years, 50.6% female) substance use (N = 33,566).

RESULTS

Latent class analysis revealed four substance use classes: nonusers (68%), low-alcohol users (recent use of beer, wine, and alcopops; 16.1%), alcohol users (recent use of alcohol and lifetime use of marijuana; 11.2%), and polysubstance users (recent use of alcohol, marijuana, and other illicit drugs; 4.7%). Results support a general pattern of adolescent substance use across all countries; however, the prevalence rates of use patterns vary for each country.

CONCLUSIONS/IMPORTANCE

The present research provides insight into substance use patterns across Europe by using a large international adolescent sample, multidimensional indicators and a variety of substances. Substance use patterns are helpful when targeting policy and prevention strategies.

Predictors of transition to heroin use among initially non-opioid dependent illicit pharmaceutical opioid users: A natural history study

BACKGROUND

Increases in illicit pharmaceutical opioid (PO) use have been associated with risk for transition to heroin use. We identify predictors of transition to heroin use among young, illicit PO users with no history of opioid dependence or heroin use at baseline.

METHODS

Respondent-driven sampling recruited 383 participants; 362 returned for at least one biannual structured interview over 36 months. Cox regression was used to test for associations between lagged predictors and hazard of transition to heroin use. Potential predictors were based on those suggested in the literature. We also computed population attributable risk (PAR) and the rate of heroin transition.

RESULTS

Over 36 months, 27 (7.5%) participants initiated heroin use; all were white, and the rate of heroin initiation was 2.8% per year (95% CI=1.9%-4.1%). Mean length of PO at first reported heroin use was 6.2 years (SD=1.9). Lifetime PO dependence (AHR=2.39, 95% CI=1.07-5.48; PAR=32%, 95% CI=-2% to 64%), early age of PO initiation (AHR=3.08, 95%; CI=1.26-7.47; PAR=30%, 95% CI=2%-59%), using illicit POs to get high but not to self-medicate a health problem (AHR=4.83, 95% CI=2.11-11.0; PAR=38%, 95% CI=12%-65%), and ever using PO non-orally most often (AHR=6.57, 95% CI=2.81-17.2; PAR=63%, 95% CI=31%-86%) were significant predictors.

CONCLUSION

This is one of the first prospective studies to test observations from previous cross-sectional and retrospective research on the relationship between illicit PO use and heroin initiation among young, initially non-opioid dependent PO users. The results provide insights into targets for the design of urgently needed prevention interventions.

Associations Between Drug and Alcohol Use Patterns and Sexual Risk in a Sample of African American Men Who Have Sex with Men

Men who have sex with men (MSM) are the largest risk group in the US HIV epidemic and African American MSM (AA MSM) are disproportionately affected. Substance-abusing sexual minorities warrant attention as they are at elevated risk for HIV, yet are not a homogeneous risk group. The purpose of this study was to use latent class analysis to identify patterns of drug and alcohol use in a sample of 359 AA MSM and examine associations with sexual risk. Three classes were identified: Individuals who used multiple substances (poly-users) (18 %), alcohol/marijuana users (33 %) and individuals who had low probability of reporting drug or problematic alcohol use (50 %). Results from multivariate analysis indicate that poly-users were older and more likely to report sex exchange and recent sexually transmitted infection compared to the other classes. Alcohol and poly-users were more likely to report sex under the influence. Identifying and defining substance use patterns can improve specification of risk groups and allocation of prevention resources.

Condoms and Contexts: Profiles of Sexual Risk and Safety Among Young Heterosexually Active Men

Heterosexual men's sexual safety behavior is important to controlling the U.S. epidemic of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). While sexual safety is often treated as a single behavior, such as condom use, it can also be conceptualized as resulting from multiple factors. Doing so can help us achieve more nuanced understandings of sexual risk and safety within partner-related contexts. We used latent class analysis with data collected online from 18- to 25-year-old heterosexually active U.S. men (n = 432) to empirically derive a typology of the patterns of sexual safety strategies they employed. Indicators were sexual risk-reduction strategies used in the past year with the most recent female sex partner: condom use, discussing sexual histories, STI testing, agreeing to be monogamous, and discussing birth control. We identified four subgroups: Risk Takers (12%), Condom Reliers (25%), Multistrategists (28%), and Relationship Reliers (35%). Partner-related context factors--number of past-year sex partners, relationship commitment, and sexual concurrency--predicted subgroup membership. Findings support tailoring STI prevention to men's sexual risk-safety subgroups. Interventions should certainly continue to encourage condom use but should also include information on how partner-related context factors and alternate sexual safety strategies can help men reduce risk for themselves and their partners.

Polydrug Use and HIV Risk Among People Who Inject Heroin in Tijuana, Mexico: A Latent Class Analysis

BACKGROUND

Although most people who inject drugs (PWID) in Tijuana, Mexico, primarily inject heroin, injection and non-injection use of methamphetamine and cocaine is common. We examined patterns of polydrug use among heroin injectors to inform prevention and treatment of drug use and its health and social consequences.

METHODS

Participants were PWID residing in Tijuana, aged ≥18 years who reported heroin injection in the past six months and were recruited through respondent-driven sampling (n = 1,025). Latent class analysis was conducted to assign individuals to classes on a probabilistic basis, using four indicators of past six-month polydrug and polyroute use: cocaine injecting, cocaine smoking or snorting, methamphetamine injecting, and methamphetamine smoking or snorting. Latent class membership was regressed onto covariates in a multinomial logistic regression.

RESULTS

Latent class analyses testing 1, 2, 3, and 4 classes were fit, with the 3-class solution fitting best. Class 1 was defined by predominantly heroin use (50.2%, n = 515); class 2 by methamphetamine and heroin use (43.7%, n = 448), and class 3 by methamphetamine, cocaine, and heroin use (6.0%, n = 62). Bivariate and multivariate analyses indicated a group of methamphetamine and cocaine users that exhibited higher-risk sexual practices and lower heroin injecting frequency, and a group of methamphetamine users who were younger and more likely to be female.

CONCLUSIONS

Discrete subtypes of heroin PWID were identified based on methamphetamine and cocaine use patterns. These findings have identified subtypes of heroin injectors who require more tailored interventions to reduce the health and social harms of injecting drug use.

A typology of prescription drug misuse: a latent class approach to differences and harms

INTRODUCTION AND AIMS

Prescription drug misuse is a considerable problem among young adults, and the identification of types of misuse among this population remains important for prevention and intervention efforts. We use latent class analysis to identify possible distinct latent groups of prescription drug misusers across multiple prescription drug types (pain killers, sedatives and stimulants).

DESIGN AND METHODS

Our data are comprised of a sample of 404 young adults recruited from nightlife scenes via time-space sampling. Through the specification of a zero-inflated Poisson latent class analysis, we evaluate differences in class membership by various demographic factors as well as assess the relationship between class membership and health outcomes, including indications of dependence, problems associated with substance use and mental health.

RESULTS

Our assessment of fit indices led to a four-class solution (dabblers, primary stimulant users, primary downers users and extensive regulars). No demographic differences existed between latent classes. The extensive regular class report the greatest number of symptoms related to dependence, greatest number of problems related to misuse and the greatest mental health problems. The dabblers report the fewest problems and symptoms, while the other two classes experiences problems and symptoms in between the classes on the extremes.

DISCUSSION AND CONCLUSIONS

Prevention efforts should take into account that young adults who misuse prescription drug have different profiles of misuse, and there may be a need for varied interventions to target these different types of misuse.

Injection and non-injection drug use and infectious disease in Baltimore City: differences by race

PURPOSE

The current study examines differences in the prevalence of biologically-confirmed hepatitis C virus (HCV), HIV, and coinfection between Black and White adult cocaine/heroin users across three drug use subgroups identified in previous research (Harrell et al., 2012): non-injection smoking crack/nasal heroin users, heroin injectors, and polydrug injectors.

RESULTS

59% of the 482 participants in the study were male. Significant race differences emerged between drug use subgroup memberships. Non-injection smoking crack/nasal heroin users were predominantly Black (75%), while heroin injectors and polydrug injectors were predominantly White (69% and 72%, respectively). Polydrug injectors accounted for nearly three quarters of the HCV positive diagnoses in Whites. Though HIV disease status, stratified by race, did not differ significantly between drug use subgroups, the non-injection smoking crack/nasal heroin subgroup contained over half of the HIV positive diagnoses in the sample and was predominantly Black. Despite much lower rates of injection, Blacks (8%) had a higher prevalence of coinfection than Whites (3%; X(2) (2)=6.18, p=.015).

CONCLUSIONS

The current findings are consistent with trends in the recent HIV transmission statistics where sexual activity has overtaken injection drug use as a HIV risk factor. The current findings also provide further support to the notion of injection drug use as an exceedingly high-risk behavior for HCV and coinfection, specifically those who are polysubstance injectors.

Use of latent class analysis approach to describe drug and sexual HIV risk patterns among injection drug users in Houston, Texas

Following latent class analysis (LCA) approach we examined patterns of HIV risk using two related domains of behavior: drug use, and sexual activity among 523 injection drug users (IDUs) recruited into the 2009 National HIV behavioral surveillance system. Using posterior probability of endorsing six drug and sexual items, we identified three distinct classes representing underlying HIV risk. Forty percent of our participants were at highest risk, 25 % at medium risk, and 35 % at lowest risk for HIV infection. Compared to the Lowest-risk class members, the Highest-risk class members had riskier drug and sexual behaviors and had higher prevalence of HIV cases (6 vs. 4 %). This analysis underscores the merit of LCA to empirically identify risk patterns using multiple indicators and our results show HIV risk varies among IDUs as their drug and sexual behaviors. Tailored and targeted prevention and treatment interventions for the dual risk pattern are required rather than for drug or sexual risk in silos.

Latent class analysis of non-opioid dependent illegal pharmaceutical opioid users in Ohio

BACKGROUND

Increases in non-medical use of pharmaceutical opioids in the U.S. have resulted in increases in opioid dependence and unintentional overdose deaths. We characterize heterogeneity in opioid use patterns among a community-based sample of 18-23 year-olds who use non-medical pharmaceutical opioids, yet are not opioid dependent.

METHODS

Respondent-driven sampling recruited 390 participants. Latent class analysis stratified by racial/ethnic group identified subgroups of non-medical opioid users based on: six-month frequency of use; number of opioid disorder criteria; oral vs. non-oral administration; number of types of opioids used; use of CNS depressants while under using opioids; and reason for opioid use. Multinomial logistic regression estimated the significance of covariates in predicting class membership.

RESULTS

Within whites and non-white groups, three classes emerged that were, generally, hierarchically ordered with respect to negative characteristics associated with non-medical opioid use. Within each group, the class with the least negative characteristics also had the highest proportion of individuals who use opioids only to self-medicate a health problem. Within each group's three classes, a larger proportion who had ≥ 2 opioid abuse and dependence disorder criteria always coincided with a larger proportion who use opioids ≥ 3 days per week, a larger proportion who used CNS depressants while under the influence of opioids, and a smaller proportion who used opioids only to self-medicate.

CONCLUSION

Differences in patterns of opioid use within each racial/ethnic group of young people who are not opioid dependent suggest the need for tailored interventions designed to reduce the risk of transition to opioid dependence.

Concurrent and simultaneous polydrug use: latent class analysis of an Australian nationally representative sample of young adults

BACKGROUND

Alcohol use and illicit drug use peak during young adulthood (around 18-29 years of age), but comparatively little is known about polydrug use in nationally representative samples of young adults. Drawing on a nationally representative cross-sectional survey (Australian National Drug Strategy Household Survey), this study examines polydrug use patterns and associated psychosocial risk factors among young adults (n = 3,333; age 19-29).

METHOD

The use of a broad range of licit and illicit drugs were examined, including alcohol, tobacco, cannabis, cocaine, hallucinogens, ecstasy, ketamine, GHB, inhalants, steroids, barbiturates, meth/amphetamines, heroin, methadone/buprenorphine, other opiates, painkillers, and tranquilizers/sleeping pills. Latent class analysis was employed to identify patterns of polydrug use.

RESULTS

Polydrug use in this sample was best described using a 5-class solution. The majority of young adults predominantly used alcohol only (52.3%), alcohol and tobacco (34.18%). The other classes were cannabis, ecstasy, and licit drug use (9.4%), cannabis, amphetamine derivative, and licit drug use (2.8%), and sedative and alcohol use (1.3%). Young adult males with low education and/or high income were most at risk of polydrug use.

CONCLUSION

Almost half of young adults reported polydrug use, highlighting the importance of post-high school screening for key risk factors and polydrug use profiles, and the delivery of early intervention strategies targeting illicit drugs.

A Latent Class Analysis of Maternal Responsiveness and Autonomy-Granting in Early Adolescence: Prediction to Later Adolescent Sexual Risk-Taking

The present study sought to extend empirical inquiry related to the role of parenting on adolescent sexual risk-taking by using latent class analysis (LCA) to identify patterns of adolescent-reported mother responsiveness and autonomy-granting in early adolescence and examine associations with sexual risk-taking in mid- and late-adolescence. Utilizing a sample of 12- to 14-year-old adolescents (N = 4,743) from the 1997 National Longitudinal Survey of Youth (NLSY97), results identified a four-class model of maternal responsiveness and autonomy-granting: low responsiveness/high autonomy-granting, moderate responsiveness/moderate autonomy-granting, high responsiveness/low autonomy-granting, high responsiveness/moderate autonomy-granting. Membership in the low responsiveness/high autonomy-granting class predicted greater sexual risk-taking in mid- and late-adolescence compared to all other classes, and membership in the high responsiveness/ moderate autonomy-granting class predicted lower sexual risk-taking. Gender and ethnic differences in responsiveness and autonomy-granting class membership were also found, potentially informing gender and ethnic disparities of adolescent sexual risk-taking.

Risk factor profiles among intravenous drug using young adults: a latent class analysis (LCA) approach

Using data from a cross-sectional study that examined health risk behaviors among urban intravenous drug-using (IDU) adolescents and young adults, this study investigated risk profiles among a high-risk sample (n=274). Risk profiles were empirically derived through latent class analysis based on indicators of engagement in health-risking behaviors, experience of abuse and violence as well as individual and family risk factors. The best fitting model was a 3-class model. Class 1 (n=95) captured participants with the lowest risk across all indicators. Compared to Class 1, Class 2 (n=128) and Class 3 (n=51) had elevated rates of engagement in health-risking behaviors as well as individual and family risk factors; however, Class 3 had the highest rate of engagement in sexual risk behavior, and backgrounds of substantial abuse and violence as well as familial psychopathology. Class 2 was the group most socioeconomically disadvantaged, with the highest percentage of participants coming from poor backgrounds, spending the longest time homeless and working the fewest months. Identifying subgroups of IDU has the potential to guide the development of more targeted and effective strategies for prevention and treatment of this high-risk population.

Simultaneous polysubstance use among Danish 3,4-methylenedioxymethamphetamine and hallucinogen users: combination patterns and proposed biological bases

OBJECTIVE

To describe patterns of simultaneous polysubstance use (SPU) among Danish 3,4-methylenedioxymethamphetamine (MDMA) ("Ecstasy") and hallucinogen users.

METHODS

A cross-sectional survey of 98 active MDMA and/or hallucinogen users recruited through homepage advertisements, flyers, and word of mouth in Denmark. Lifetime and recent substance use and SPU at last recalled use was described by structured interviews. Hair samples from a subset of participants were analyzed for MDMA.

RESULTS

The participants had used an average of 12.6 (95% confidence interval: 11.7-13.4) psychoactive substances during their lifetime. SPU was prevalent among MDMA, d-lysergic acid diethylamide (LSD), and psilocybin users, in particular with alcohol and cannabis. Among MDMA users, 69% had combined MDMA with amphetamines, 56% with hallucinogens, and 47% with cocaine. At last recalled use, MDMA was taken with 2.1 ± 1.2 substances in 32 different combinations. The participants preferred specific drug combinations and named several, which in their experience enhanced or counteracted each other. Alcohol and cannabis were typically used before, during, and after MDMA, LSD, and psilocybin, whereas amphetamines were predominantly taken before these substances. When LSD was combined with MDMA, the majority took MDMA after LSD.

CONCLUSIONS

Simultaneous polysubstance use was common among Danish MDMA and hallucinogen users, and patterns of preferred substance combinations were evident.

Understanding subtypes of inner-city drug users with a latent class approach

AIMS

We empirically identified subtypes of inner-city users of heroin and cocaine based on type of drug used and route of administration.

METHOD

The sample was recruited from the communities in Baltimore, MD (SHIELD study) and consisted of 1061 participants who used heroin and or cocaine in the past 6 months on a weekly basis or more. Latent class analysis (LCA) was used to identify subtypes of drug users based on type of drug and route of administration. Logistic regression was used to compare the subtypes on depressive symptoms, injection risk and drug network compositions.

FINDINGS

Inner-city drug users were classified into five subtypes: three subtypes of injection drug users (IDUs) [heroin injecting (n=134; 13%), polydrug and polyroute (n=88, 8%), and heroin and cocaine injecting (n=404, 38%)], and two subtypes with low proportions of IDUs (LIDUs) [heroin snorting (n=275, 26%) and crack smoking (n=160; 14%)]. The polydrug and polyroute subtype had the highest depressive symptoms risk among all subtypes. Injection risk was lowest in the heroin injecting subtype and significantly differed from heroin and cocaine injecting subtype. The IDU subtypes also varied in the drug network compositions. The LIDU subtypes had similar depressive symptoms risk but vastly differed in the drug network compositions.

CONCLUSIONS

Subgroups of inner-city cocaine and heroin users based on type and route of administration differed in their depressive symptoms, injection risk and drug network compositions. Future studies should longitudinally examine factors associated with transitioning across these subtypes to better inform prevention and treatment efforts.

Perceived risk associated with ecstasy use: a latent class analysis approach

This study aims to define categories of perceived health problems among ecstasy users based on observed clustering of their perceptions of ecstasy-related health problems. Data from a community sample of ecstasy users (n=402) aged 18 to 30, in Ohio, was used in this study. Data was analyzed via Latent Class Analysis (LCA) and Regression. This study identified five different subgroups of ecstasy users based on their perceptions of health problems they associated with their ecstasy use. Almost one third of the sample (28.9%) belonged to a class with "low level of perceived problems" (Class 4). About one fourth (25.6%) of the sample (Class 2), had high probabilities of "perceiving problems on sexual-related items", but generally low or moderate probabilities of perceiving problems in other areas. Roughly one-fifth of the sample (21.1%, Class 1) had moderate probabilities of perceiving ecstasy health-related problems in all areas. A small proportion of respondents (11.9%, Class 5) had high probabilities of reporting "perceived memory and cognitive problems", and of perceiving "ecstasy-related problems in all areas" (12.4%, Class 3). A large proportion of ecstasy users perceive either low or moderate risk associated with their ecstasy use. It is important to further investigate whether lower levels of risk perception are associated with persistence of ecstasy use.

Patterns of polydrug use in Great Britain: findings from a national household population survey

BACKGROUND

Polydrug use potentially increases the likelihood of harm. As little is known about polydrug use patterns in the general population, it is difficult to determine patterns associated with highest likelihood.

METHODS

Latent class analysis was performed on nine illicit substance groups indicating past year use of cannabis, cocaine, amphetamines, ecstasy, LSD, mushrooms, amyl nitrate, tranquillisers and heroin or crack. Analyses were based on data from a large multi-stage probability sample of the population of Great Britain (n=8538) collected in 2000. Multinomial logistic regression was performed highlighting associations between classes, and demographic and mental health variables.

RESULTS

A three class solution best described patterns of polydrug use; wide range, moderate range, and no polydrug use. For males and young people, there was a significantly increased chance of being in the wide and moderate range polydrug use groups compared to the no polydrug use class. Hazardous drinking was more likely in the wide and moderate polydrug classes with odds ratios of 9.99 and 2.38 (respectively) compared to the no polydrug use class. Current smokers were more likely to be wide and moderate range polydrug users compared to the no polydrug use class with odds ratios of 4.53 and 5.85 respectively. A range of mental health variables were also related to class membership.

CONCLUSIONS

Polydrug use in Great Britain can be expressed as three distinct classes. Hazardous alcohol use and tobacco use were strongly associated with illicit polydrug use, polydrug use appeared to be significantly associated with mental health, particularly lifetime suicide attempts.

MDMA ("ecstasy") abuse as an example of dopamine neuroplasticity

A number of reviews have focused on the short- and long-term effects of MDMA and, in particular, on the persistent deficits in serotonin neurotransmission that accompany some exposure regimens. The mechanisms underlying the serotonin deficits and their relevance to various behavioral and cognitive consequences of MDMA use are still being debated. It has become clear, however, that some individuals develop compulsive and uncontrolled drug-taking that is consistent with abuse. For other drugs of abuse, this transition has been attributed to neuroadaptations in central dopamine mechanisms that occur as a function of repeated drug exposure. A question remains as to whether similar neuroadaptations occur as a function of exposure to MDMA and the impact of serotonin neurotoxicity in the transition from use to abuse. This review focuses specifically on this issue by first providing an overview of human studies and then reviewing the animal literature with specific emphasis on paradigms that measure subjective effects of drugs and self-administration as indices of abuse liability. It is suggested that serotonin deficits resulting from repeated exposure to MDMA self-administration lead to a sensitized dopaminergic response to the drug and that this sensitized response renders MDMA comparable to other drugs of abuse.

CDC HIV testing guidelines and the rapid and conventional testing practices of homeless youth

The study's aims were to describe rapid and conventional HIV testing practices and referrals/linkages to services posttest among homeless youth in New York City. We also examined variation among service-involved youth, street youth, and "nomads." Respondent-driven sampling was used to recruit 217 homeless youth who participated in structured interviews. Almost all youth were tested in the past year (82%). Most received pretest/posttest counseling (> 77%). Rapid testing was common and conducted in diverse settings. However, youth reported that rates of referral/linkage to services posttest were low (< 44.4%). Service-involved youth were significantly more likely to receive rapid testing, be tested in the past year, and be tested at a high frequency. Street youth and nomads, those at highest risk for poor health outcomes, had less access to testing and may require creative, low-threshold services. Further, a better understanding of barriers to the use of referrals/linkages to services posttest is needed.

Modifiable risk factors of ecstasy use: risk perception, current dependence, perceived control, and depression

Risk perception, perceived behavioral control of obtaining ecstasy (PBC-obtaining), current ecstasy dependence, and recent depression have been associated with past ecstasy use, however, their utility in predicting ecstasy use has not been demonstrated. This study aimed to determine whether these four modifiable risk factors could predict ecstasy use after controlling for socio-demographic covariates and recent polydrug use. Data from 601 ecstasy users in the National Institute on Drug Abuse-funded TriCity Study of Club Drug Use, Abuse and Dependence were analyzed using multivariate logistic regression. Participants were interviewed twice within a 2-week period using standardized instruments. Thirteen percent (n = 80) of the participants reported using ecstasy between the two interviews. Low risk perception, high PBC-obtaining (an estimated ecstasy procurement time < 24h), and current ecstasy dependence were statistically associated with ecstasy use between the two interviews. Recent depression was not a significant predictor. Despite not being a target predictor, recent polydrug use was also statistically associated with ecstasy use. The present findings may inform the development of interventions targeting ecstasy users.

Typology of club drug use among young adults recruited using time-space sampling

The present study examined patterns of recent club drug use among 400 young adults (18-29) recruited using time-space sampling in NYC. Subjects had used at least one of six club drugs (methylenedioxymethamphetamine (MDMA), ketamine, gamma-hydroxybutyrate (GHB), cocaine, methamphetamine, and D-lysergic acid diethylamide (LSD)) within the prior 3 months. We used latent class analysis (LCA) to estimate latent groups based on patterns of recent club drug use and examined differences in demographic and psychological variables by class. A 3-class model fit the data best. Patterns were: Primary cocaine users (42% of sample), Mainstream users (44% of sample), and Wide-range users (14% of sample). Those most likely to be Primary cocaine users were significantly less likely to be heterosexual males and had higher educational attainment than the other two classes. Those most likely to be Wide-range users were less likely to be heterosexual females, more likely to be gay/bisexual males, dependent on club drugs, had significantly greater drug and sexual sensation seeking, and were more likely to use when experiencing physical discomfort or pleasant times with others compared to the other two groups. Findings highlight the utility of using person-centered approaches to understand patterns of substance use, as well as highlight several patterns of club drug use among young adults.

The variety of ecstasy/MDMA users: results from the National Epidemiologic Survey on alcohol and related conditions

This study investigates the potential heterogeneity of ecstasy or MDMA (3,4-methylenedioxy-N-methylamphetamine) users. Data came from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Latent class analysis (LCA) and multinomial logistic regression procedures were used to identify subtypes of ecstasy users. Approximately 1.6% (n = 562) of adult participants (N = 43,093) reported lifetime ecstasy use. LCA identified three subtypes of ecstasy users. Class 1 exhibited pervasive use of most drug classes (ecstasy-polydrug users, 37%). Class 2 reported a high rate of use of marijuana and cocaine and a moderate use of amphetamines (ecstasy-marijuana-stimulant users, 29%). Class 3 was characterized by a high rate of use of marijuana and a low use of primarily prescription-type drugs (ecstasy-marijuana users, 34%). Subtypes were distinguished by family income, history of substance abuse treatment, and familial substance abuse. Class 1 exhibited the highest prevalence of disorders related to the use of marijuana (77%), tobacco (66%), amphetamines (36%), opioids (35%), sedatives (31%), and tranquilizers (30%). The recent resurgence in ecstasy use among adults underscores the need to monitor trends in its use.

The high prevalence of substance use disorders among recent MDMA users compared with other drug users: Implications for intervention

AIM

In light of the resurgence in MDMA use and its association with polysubstance use, we investigated the 12-month prevalence of substance use disorders (SUDs) among adult MDMA users to determine whether they are at risk of other drug-related problems that would call for targeted interventions.

METHODS

Data were drawn from the 2006 National Survey on Drug Use and Health. Past-year adult drug users were grouped into three mutually exclusive categories: 1) recent MDMA users, who had used the drug within the past year; 2) former MDMA users, who had a history of using this drug but had not done so within the past year; and 3) other drug users, who had never used MDMA. Logistic regression procedures were used to estimate the association between respondents' SUDs and MDMA use while adjusting for their socioeconomic status, mental health, age of first use, and history of polydrug use.

RESULTS

Approximately 14% of adults reported drug use in the past year, and 24% of those past-year drug users reported a history of MDMA use. Recent MDMA users exhibited the highest prevalence of disorders related to alcohol (41%), marijuana (30%), cocaine (10%), pain reliever/opioid (8%), and tranquilizer (3%) use. Adjusted logistic regression analyses revealed that, relative to other drug users, those who had recently used MDMA were twice as likely to meet criteria for marijuana and pain reliever/opioid use disorders. They were also about twice as likely as former MDMA users to meet criteria for marijuana, cocaine, and tranquilizer use disorders.

CONCLUSIONS

Seven out of ten recent MDMA users report experiencing an SUD in the past year. Adults who have recently used MDMA should be screened for possible SUDs to ensure early detection and treatment.

Illicit use of pharmaceutical opioids among young polydrug users in Ohio

This study, conducted in Columbus, Ohio, identified the predictors of current (past 30 day) illicit use of pharmaceutical opioids among young individuals (n=402) with a history of MDMA/ecstasy use who were recruited in 2002-2003 using respondent-driven sampling. To be eligible, participants had to be 18-30 years old, not involved in a drug abuse treatment, and report MDMA/ecstasy use at least once in the past 6 months. About 81% reported lifetime, and more than 31% reported current illicit use of pharmaceutical opioids. Logistic regression analysis revealed that illicit use of pharmaceutical tranquilizers and pharmaceutical stimulants were the strongest predictors of illicit use of pharmaceutical opioids. Risk of pharmaceutical opioid use was also greater among those who had higher levels of depressive symptoms and reported current use of hallucinogens and inhalants. Our findings suggest that the non-medical use of pharmaceutical opioids is a part of polydrug use practices that often incorporate illicit use of other prescription drugs. The observed relationship between depressive symptoms and illicit use of pharmaceutical opioids may have important implications for prevention programming and should be examined in future research.

Patterns of risky behaviors associated with methamphetamine use among young Thai adults: a latent class analysis

PURPOSE

Methamphetamine (MA) is the leading illicit drug in Thailand among youth and young adults. Sexual risk behaviors are associated with methamphetamine use, but few data are available on the daily context of methamphetamine use. We developed an inductive behavioral typology that young Thais engage in while using methamphetamine.

METHODS

We conducted a cross-sectional study in Chiang Mai, Thailand, in 2005-2006 among 1,162 street-recruited methamphetamine smokers 18-25 years of age. Data collected included sociodemographic characteristics, sexual behaviors, and drug use patterns. Latent class analysis was used to describe patterns of activities in which participants reported engaging directly after using MA. Logistic regression was used to examine univariate correlates of class membership, separately by gender.

RESULTS

Participants were 75% male with a median age of 19 years. More than half of participants reported frequent alcohol use (>or=4 days/week) and half of the sample reported smoking MA >or=2 days/ week. Three classes of activities emerged for male participants (n = 863): "work" (job related); "high-risk behaviors" (motorcycle riding, fighting, sex); and "combined" (all activities). Two classes emerged for the women (n = 299): "work" (housework) and "high-risk behaviors." "High-risk behaviors" and "combined" (men only) classes were associated with more frequent alcohol and methamphetamine use compared with the "work" class.

CONCLUSIONS

Our study found a distinct typology of behaviors associated with substance abuse among young adults in Thailand. Behavioral typologies allow a better understanding of the nuances of "risky" behaviors and might prove useful in targeting interventions.

Multiple murder and criminal careers: a latent class analysis of multiple homicide offenders

PURPOSE

To construct an empirically rigorous typology of multiple homicide offenders (MHOs).

METHOD

The current study conducted latent class analysis of the official records of 160 MHOs sampled from eight states to evaluate their criminal careers.

RESULTS

A 3-class solution best fit the data (-2LL=-1123.61, Bayesian Information Criterion (BIC)=2648.15, df=81, L(2)=1179.77). Class 1 (n=64, class assignment probability=.999) was the low-offending group marked by little criminal record and delayed arrest onset. Class 2 (n=51, class assignment probability=.957) was the severe group that represents the most violent and habitual criminals. Class 3 (n=45, class assignment probability=.959) was the moderate group whose offending careers were similar to Class 2.

CONCLUSION

A sustained criminal career with involvement in versatile forms of crime was observed for two of three classes of MHOs. Linkages to extant typologies and recommendations for additional research that incorporates clinical constructs are proffered.

Tri-city study of Ecstasy use problems: a latent class analysis

This study used latent class analysis to examine distinctive subtypes of Ecstasy users based on 24 abuse and dependence symptoms underlying standard DSM-IV criteria. Data came from a three site, population-based, epidemiological study to examine diagnostic nosology for Ecstasy use. Subject inclusion criteria included lifetime Ecstasy use exceeding five times and once in the past year, with participants ranging in age between 16 and 47 years of age from St. Louis, Miami, U.S. and Sydney, Australia. A satisfactory model typified four latent classes representing clearly differentiated diagnostic clusters including: (1) a group of sub-threshold users endorsing few abuse and dependence symptoms (negatives), (2) a group of 'diagnostic orphans' who had characteristic features of dependence for a select group of symptoms (mild dependent), (3) a 'transitional group' mimicking the orphans with regard to their profile of dependence also but reporting some abuse symptoms (moderate dependent), and (4) a 'severe dependent' group with a distinct profile of abuse and dependence symptoms. A multinomial logistic regression model indicated that certain latent classes showed unique associations with external non-diagnostic markers. Controlling for demographic characteristics and lifetime quantity of Ecstasy pill use, criminal behavior and motivational cues for Ecstasy use were the most efficient predictors of cluster membership. This study reinforces the heuristic utility of DSM-IV criteria applied to Ecstasy but with a different collage of symptoms that produced four distinct classes of Ecstasy users.

Patterns of health-related quality of life and patterns associated with health risks among Rhode Island adults

Background

Health-related quality of life (HRQOL) has become an important consideration in assessing the impact of chronic disease on individuals as well as in populations. HRQOL is often assessed using multiple indicators. The authors sought to determine if multiple indicators of HRQOL could be used to characterize patterns of HRQOL in a population, and if so, to examine the association between such patterns and demographic, health risk and health condition covariates.

Methods

Data from Rhode Island's 2004 Behavioral Risk Factor Surveillance System (BRFSS) were used for this analysis. The BRFSS is a population-based random-digit-dialed telephone survey of adults ages 18 and older. In 2004 RI's BRFSS interviewed 3,999 respondents. A latent class regression (LCR) model, using 9 BRFSS HRQOL indicators, was used to determine latent classes of HRQOL for RI adults and to model the relationship between latent class membership and covariates.

Results

RI adults were categorized into four latent classes of HRQOL. Class 1 (76%) was characterized by good physical and mental HRQOL; Class 2 (9%) was characterized as having physically related poor HRQOL; Class 3 (11%) was characterized as having mentally related poor HRQOL; and Class 4 (4%) as having both physically and mentally related poor HRQOL. Class 2 was associated with older age, being female, unable to work, disabled, or unemployed, no participation in leisure time physical activity, or with having asthma or diabetes. Class 3 was associated with being female, current smoking, or having asthma or disability. Class 4 was associated with almost all the same predictors of Classes 2 and 3, i.e. older age, being female, unable to work, disabled, or unemployed, no participation in leisure time physical activity, current smoking, with having asthma or diabetes, or with low income.

Conclusion

Using a LCR model, the authors found 4 distinct patterns of HRQOL among RI adults. The largest class was associated with good HRQOL; three smaller classes were associated with poor HRQOL. We identified the characteristics of subgroups at higher-risk for each of the three classes of poor HRQOL. Focusing interventions on the high-risk populations may be one approach to improving HRQOL in RI.

Identifying persons with treated asthma using administrative data via latent class modelling

OBJECTIVE

To develop a parsimonious model of the respiratory patient population in British Columbia (BC), Canada through latent class modelling (LCM), using administrative data records and to assess conventional case definitions for asthma in relation to model-based case selection.

DATA SOURCES

1996-2001 data from linked provincial databases containing fee-for-service physician billing records, hospital inpatient separation abstracts, and prescription drug purchase records for 1.9 million BC respiratory patients.

STUDY DESIGN

This is a retrospective methodological/descriptive study that assesses case definitions for asthma in terms of sensitivity and specificity using a model fitted to seven physician, hospital and medication utilization markers in place of a conventional gold standard.

DATA COLLECTION

We computed values of the treatment markers for each of the 5 years for each patient aged 5-55 years who had had at least one occurrence of a respiratory diagnosis code.

PRINCIPAL FINDINGS

The marker for prescription of short-acting beta agonists (SABAs) consistently had the highest sensitivity. Markers' specificities ranged from 0.97 to 1.0. The conventional case definitions' sensitivities were 0.41-0.87; specificities ranged from 0.98 to 0.997. Model-based estimates of asthma prevalence increased from 827/10,000 in 1996 to 992/10,000 in 2001. Conventional case definitions' estimates were consistently lower.

CONCLUSIONS

The linkage between utilization and case status is more complex than conventional case definitions allow for. LCM-based case classification was consistent over time and tends to lead to larger prevalence estimates than conventional definitions. The estimated increases in asthma prevalence are reliable. LCM provides health services planners with a useful probability-based approach for developing and assessing case definitions and estimating case prevalence.

Poly-Drug Use among Ecstasy Users: Separate, Synergistic, and Indiscriminate Patterns

The main objective of this paper is to explore poly-drug use among young adult ecstasy users. This phenomenon of using multiple substances within a specific time period is multi-faceted. In this paper, we focus on the various patterns of poly-drug use and the reasons for combining multiple drugs among ecstasy users. Using a mixed-methods design, we conducted interviews with young adults who used ecstasy and other licit and illicit drugs in the past 90 days. Based on the qualitative analyses, we define three distinct types of poly-drug experiences: separate, synergistic, and indiscriminate use. While separate and synergistic poly-drug use tended to be intentional, indiscriminate poly-drug use often was unintentional. These findings show the importance of recognizing poly-drug use as a common phenomenon. The findings presented here suggest areas for further research aimed at identifying risk and protective behaviors and risk reduction strategies.

The role of peers in the initiation and continuation of ecstasy use

This study is a supplement to the Netherlands XTC Toxicity Study (NeXT), funded by grants from the Netherlands Organisation for Health Research and Development as part of its Addiction Programme. To better understand the processes of peer influence and peer selection, in a field study 106 Ecstasy users (67M/39F, average age 25.4 years) were interviewed face-to-face in Amsterdam in 2005. In the initiation of Ecstasy use, peer influence emerged as the dominating mechanism; peer selection was uncommon. In the continuation of Ecstasy use, peer influence and peer selection occurred reciprocally in a dynamic process, although peer influence made a greater relative contribution. Our study confirms that peer influence is a multidimensional process: influence was quite often reciprocal (with respondents both exerting and undergoing influence) and it could have both restraining and encouraging effects on ecstasy use. The study's limitations are noted.

Depressive symptomatology in young adults with a history of MDMA use: a longitudinal analysis

Research suggests that methylenedioxymethamphetamine (MDMA)/;ecstasy' can cause serotonin depletion as well as serotonergic neurodegradation that may result in depression. This longitudinal study used the Beck Depression Inventory (BDI-II) to assess depressive symptomatology every six months over a two-year period among a community sample of young adult MDMA/;ecstasy' users (n = 402). Multilevel growth modeling was used to analyze changes in BDI scores. Between baseline and 24 months, the mean BDI score declined from 9.8 to 7.7. Scores varied significantly across individuals at baseline and declined at a rate of 0.36 points every six months. Persons with higher baseline scores were more likely to have their scores decrease over time. Several factors were significantly associated with score levels, independent of time: gender - men's scores were lower than women's; ethnicity - whites' scores were lower than those of non-whites; education - persons with at least some university education had scores that were lower than those without any college experience; benzodiazepines - current users' scores were higher than non-users'; opioids - current users' scores were higher than non-users'; and cumulative ecstasy use - people who had used MDMA more than 50 times had scores that were higher than persons who had used the drug less often. The results reported here show low levels of depressive symptoms among a sample that, after 24 months, consisted of both current and former MDMA users. The low and declining mean scores suggest that for most people MDMA/;ecstasy' use does not result in long-term depressive symptomatology.

Symptom clusters in acute myocardial infarction: a secondary data analysis

BACKGROUND

Early recognition of acute myocardial infarction (AMI) symptoms and reduced time to treatment may reduce morbidity and mortality. People having AMI experience a constellation of symptoms, but the common constellations or clusters of symptoms have yet to be identified.

OBJECTIVES

To identify clusters of symptoms that represent AMI.

METHODS

This was a secondary data analysis of nine descriptive, cross-sectional studies that included data from 1,073 people having AMI in the United States and England. Data were analyzed using latent class cluster analysis, an a theoretical method that uses only information contained in the data.

RESULTS

Five distinct clusters of symptoms were identified. Age, race, and sex were statistically significant in predicting cluster membership. None of the symptom clusters described in this analysis included all of the symptoms that are considered typical. In one cluster, subjects had only a moderate to low probability of experiencing any of the symptoms analyzed.

DISCUSSION

Symptoms of AMI occur in clusters, and these clusters vary among persons. None of the clusters identified in this study included all of the symptoms that are included typically as symptoms of AMI (chest discomfort, diaphoresis, shortness of breath, nausea, and lightheadedness). These AMI symptom clusters must be communicated clearly to the public in a way that will assist them in assessing their symptoms more efficiently and will guide their treatment-seeking behavior. Symptom clusters for AMI must also be communicated to the professional community in a way that will facilitate assessment and rapid intervention for AMI.