Heroin Sniffers: Between Two Worlds

Abstract

This article examines individual and social factors associated with initiation of illicit drug injection, with a focus on racial differences. Data were derived from a cross-sectional survey of young injection and noninjection drug users in Baltimore, Maryland. Participants were aged 15 to 30 and had initiated use of heroin, cocaine, and/or crack within the prior five years. Bivariate and multivariate logistic regression models were used to identify correlates of injection initiation. Of 579 drug users, 73% were injectors, 56% were male, and 41% were African American. In a multivariate model controlling for age, correlates of injection initiation were: being an African American male [Adjusted Odds Ratio (AOR): 0.08; 95% Confidence Interval (CI): 0.04, 0. 17] or female (AOR = 0.12; 95%CI: 0.06, 027) compared to being a White male; younger age of first use of alcohol, marijuana, or inhalants (AOR=0.73; 95%CI: 0.65, 0.82); shorter time between first use of alcohol, marijuana, or inhalants and first use of heroin, crack, or cocaine (per year decrease, AOR=0.63, 95%CI: 0.40, 0.87); parental drug use (AOR=0.54, 95%CI: 0.32, 0.92); seeing someone inject prior to injection, AOR=1.96, 95%CI: 1.0 1, 3.50); and crack smoking (AOR=1.77, 95%CI: 1.07, 2.99). Early drug use panems and drug expos we factors are associated with initiation injection. Interventions are needed that target noninjection drug users to prevent transition to injection drug use.     

Prevalence and correlates of opiate overdose among young injection drug users in a large U.S. city

OBJECTIVES: The current study examines the prevalence and correlates of witnessing and experiencing opiate overdoses among a sample of young, injection drug users (IDUs) and non-injection drug users (NIDUs) in Baltimore, MD. METHODS: Data were derived from a longitudinal study of 15-30 year old IDUs and NIDUs (N=309) who had initiated heroin, cocaine, and/or crack use within 5 years prior to study enrollment. Chi-square and Wilcoxon rank-sum tests were used in bivariate analyses of demographic and drug use variables with each of the two dependent variables. Multivariate logistic regression models were used to identify correlates of experiencing and witnessing overdose. RESULTS: Twenty-nine percent of participants reported having ever experienced an opiate overdose and 57% reported having ever witnessed an overdose. Having ever experienced an opiate overdose was independently associated with being White (Adjusted Odds Ratio [AOR]=3.2; 95% Confidence Interval [CI]: 1.6, 6.4) recent homelessness (AOR=2.9; 95%CI: 1.5, 5.7); and length of injection, 5.6-6.9 years versus <5.6 years (AOR=4.0; 95%CI: 1.8-8.9); injecting 7.0-7.9 years versus <5.6 years (AOR=2.5; 95%CI: 1.03-6.1); injecting >8 versus <5.6 years (AOR=4.7; 95%CI: 2.2-10.2). Having witnessed an opiate overdose was independently associated with being White (AOR=2.4; 95%CI: 1.4, 4.1) and injecting >8 years versus <5.6 years (AOR=2.2; 95%CI: 1.2, 4.0). CONCLUSIONS: This study documents the high prevalence of witnessing and experiencing opiate overdoses among young, newly initiated IDUs and NIDUs. The results could inform the growing number of overdose prevention efforts throughout the U.S.     

Characteristics of injection drug users who participate in drug dealing: implications for drug policy

So-called "balanced" drug policy couples enforcement initiatives targeting drug dealers with health-focused interventions serving addicted individuals. There are few evaluations of this approach, and little is known about how these two populations may overlap. We evaluated factors associated with drug dealing among injection drug users (IDUs) in Vancouver, Canada, and examined self-reported drug-dealing roles and reasons for dealing. Among 412 IDUs seen from March through December 2005, 68 (17%) had dealt drugs during the previous six months. Variables independently associated with drug dealing included: recent incarceration (adjusted odds ratio [AOR] = 2.9; 95%CI: 1.4-6.0); frequent heroin injection (AOR = 2.5; 95%CI: 1.4-4.6); frequent cocaine injection (AOR = 2.0; 95%CI: 1.1-3.8); and recent overdose (AOR = 2.7; 95%CI: 1.0-7.3). The most common drug-dealing roles were direct selling (82%), middling (35%), and steering (19%), while the most common reasons for dealing included obtaining drugs (49%) and money (36%). Drug dealing among IDUs was predicted by several markers of higher intensity addiction, and drug-dealing IDUs tended to occupy the most dangerous positions in the drug-dealing hierarchy. These findings suggest that elements of "balanced" drug policies may undermine each other and indicate the need for alternative interventions.     

Is inhalant use a risk factor for heroin and injection drug use among adolescents in the United States?

PURPOSE: We examined whether inhalant use was associated with heroin and injection drug use (IDU) among adolescents aged 12 to 17 in the United States. METHODS: Data were drawn from the 2002/2003 administrations of the National Survey on Drug Use and Health (NSDUH). We conducted logistic regression analyses to estimate associations of inhalant use with heroin use, heroin injection, and IDU, respectively, among adolescent drug users (N=8161). RESULTS: Approximately 30.9% of adolescents had ever used at least one illicit drug. More than one-fifth (22.2%) of adolescents were past-year or recent drug users. Among past-year adolescent drug users, 1.4% had progressed to heroin use and 1.2% reported IDU. Adolescents who had used inhalants and marijuana were 2.8 and 2.9 times as likely as adolescents who had used marijuana but not inhalants to report heroin use and any IDU, respectively. Adolescents who had used inhalants or other drugs but not marijuana were unlikely to use heroin. However, inhalant users, irrespective of their marijuana use histories, had greater odds of IDU than drug users who had not used inhalants. Adolescent drug users who were females, school dropouts, whites, or delinquents had significantly increased odds of heroin use and IDU. Cigarette smoking before the age of 15 was strongly associated with heroin use, and a history of foster care placement was associated with IDU. CONCLUSIONS: This national study of American adolescents identifies several subgroups of recent drug users, such as females, school dropouts, and youth who have used inhalants and marijuana, which have substantially increased odds of heroin use and IDU. Screening, prevention, and treatment interventions targeted to these groups might reduce medical and social complications of heroin use and IDU.     

An exploration of alcohol use severity and route of drug administration among persons that use heroin and cocaine

ABSTRACT

Background: Alcohol use is prevalent among populations of persons that use illicit drugs. Problematic alcohol use among persons that use heroin and cocaine has been associated with poor treatment adherence, abstinence maintenance, and mental health concerns. Fully exploring how alcohol use severity interacts with route of administration (ROA) may be of notable importance in development of treatment protocols for persons that use heroin and cocaine. Methods: Data from a neurological and sociobehavioral assessment of risk factors among injection and noninjection drug users known as the NEURO-HIV Epidemiologic Study was used in the analyses. Participants (N = 551) included those who reported their level of past-30-day alcohol use and past-6-month heroin and cocaine use. Results: Multiple logistic regression analyses found that both problematic and moderate alcohol users were significantly less likely than abstainers to report injecting heroin and cocaine. Both problematic and moderate alcohol users were significantly more likely than abstainers to snort substances. Conclusions: Alcohol use may play a role in promoting or impeding the use of substances through certain ROAs. Treatment protocols that transition persons that use injection heroin and cocaine to noninjection use of these substances may be used in conjunction with treatments that reduce alcohol consumption as a means to reduce noninjection drug use.     

Risk profile of individuals who provide assistance with illicit drug injections

BACKGROUND: Assisted injection is a common practice among injection drug users (IDU) that carries significant risk for health-related harm. However, little is known about the individuals who provide assistance with injections. METHODS: We evaluated factors associated with providing help injecting among participants enrolled in the Vancouver Injection Drug User Study (VIDUS) using univariate and logistic regression analyses. We also examined self-reported relationships between the provider and the receiver of assisted injection, if compensation was provided for assistance, and what type of compensation was given. RESULTS: Of the 704 IDU eligible for this analysis, 193 (27.4%) had provided help injecting during the last 6 months. Variables independently associated with providing help injecting included: lending one's own syringe (adjusted odds ratio [AOR] = 3.99, p = 0.004); frequent heroin injection (AOR = 3.75, p < 0.001); unstable housing (AOR = 2.15, p < 0.001); binge drug use (AOR = 2.01, p = 0.012); frequent cocaine injection (AOR = 1.95, p = 0.002); and frequent use of crack cocaine (AOR = 1.85, p = 0.002). Help was most often provided to a casual (47.2%) or a close friend (41.5%). Of the 96 (49.7%) individuals who received compensation for providing help, the most common forms of compensation were drugs (89.6%) and money (45.8%). CONCLUSION: Providing help injecting was common among IDU in this cohort and was associated with various high-risk behaviours, including elevated levels of syringe lending. These findings indicate the need for interventions that offset the risks associated with this dangerous practice.     

Sexual risk and HIV infection among drug users in New York City: a pilot study

Measures of sexual health were assessed during 2008-2009 in a New York City sample of 102 injection and noninjection users of heroin, cocaine, or crack. There was considerable overlap and transitioning between crack smoking and injecting. Crack users were also significantly more likely to be gay, lesbian, or bisexual than other drug users. In multivariate analysis, HIV infection was independently associated with crack use and with being gay or bisexual. In New York City, HIV prevention for drug users has focused on syringe access, safe injection, and drug user treatment, but further progress in HIV control will require strategies to address sexual health among people who use drugs. The study's limitations are noted.     

High-risk behaviors associated with transition from illicit non-injection to injection drug use among adolescent and young adult drug users: a case-control study

OBJECTIVE: The goal of our study was to elucidate characteristics of persons likely to transition into injection drug use so that an identifiable group with high-risk for blood-borne infection may be targeted for interventions. METHODS: An age-matched case-control analysis was performed from a cohort study in Baltimore, 1997-1999, of street-recruited non-injection and injection drug users (IDUs), aged 15-30. Cases were IDUs injecting < or = 2 years and controls were age-matched persons who used non-injection heroin, cocaine or crack. At baseline, all were interviewed about prior year-by-year behaviors; analysis using conditional logistic regression was based on information for the year prior to injection onset for the case and the same calendar time for the controls as well as recent behaviors for both groups. RESULTS: Of 270 participants, most were African American (78%), female (61%), and HIV seroprevalence was 7% at baseline. IDUs were significantly more likely than controls to be non-African American (adjusted odds ratio (AOR)=0.09) and report high school dropout (AOR=2.32), early sex-trading (AOR=2.72), and recent violence victimization (AOR=9.28). CONCLUSION: Given that new injectors are at high-risk for HIV and hepatitis yet difficult to reach for prevention efforts, our data suggest some categories to use to target non-injectors who are likely to transition into injection use.     

Early onset of drug and polysubstance use as predictors of injection drug use among adult drug users

Early onset of alcohol, marijuana, and cigarette use is an indicator of later substance use problems in adulthood such as alcohol or other drug dependence. This paper seeks to address the association between early onset alcohol, marijuana, cigarette, and polysubstance use with injection drug use among recent illicit drug users. The current study used baseline data from the Baltimore site of the NEURO-HIV Epidemiologic Study, an investigation of neuropsychological and social-behavioral risk factors of HIV, hepatitis A, hepatitis B, and Hepatitis C among both injection and non-injection drug users in Baltimore, Maryland. The present study used a subset (N=651) of the larger parent study that identified as White or Black, and reported any drug use in the past 6 months. In the full sample slightly more than half (52.5%) of study participants were IDUs. IDUs differed from non-IDUs on age of initiation for cigarettes, marijuana, and alcohol, with IDUs initiating the use of all three substances significantly earlier than non-IDUs. IDUs also had significantly greater proportions of early onset of alcohol (χ(2)=19.71, p<.01), cigarette (χ(2)=11.05, p<.01), marijuana (χ(2)=10.83, p<.01), and polysubstance use (χ(2)=23.48, p<.01) than non-IDUs. After adjusting for age, gender, and race/ethnicity, only participants identified as early onset alcohol users (AOR=1.47, 95% CI: 1.00-2.18) and early onset polysubstance users (AOR=1.62, 95% CI: 1.10-2.38) were more likely to have IDU status than those who reported initiating substance use later. IDU status was then stratified by race/ethnicity. After controlling for age and gender, only early polysubstance use was a significant predictor of IDU status for Whites (AOR=2.06, 95% CI: 1.07-3.93). Consistent with literature on early substance initiation and later illicit substance use, early onset of alcohol and polysubstance use is an important risk factor for IDU in adulthood.     

Heroin overdose among young injection drug users in San Francisco

OBJECTIVES: We sought to identify prevalence and predictors of heroin-related overdose among young injection drug users (IDU). METHODS: A total of 795 IDU under age of 30 years were interviewed in four neighbourhoods in San Francisco, California, USA. Participants were recruited as part of a broader study of HIV, hepatitis B and C among injecting drug users in San Francisco using street outreach and snowball techniques. Independent predictors of recent heroin overdose requiring intervention were determined using regression analysis. RESULTS: Of 795 injecting drug users under age of 30 years, 22% (174/795) of participants reported a heroin overdose in the last year. In stepwise multiple logistic regression, independent predictors of recent heroin overdose were lifetime incarceration exceeding 20 months (odds ratio (OR) = 2.99, 95% confidence interval (CI) = 1.52-5.88); heroin injection in the last 3 months (OR = 4.89, 95% CI = 2.03-11.74); cocaine injection in the last 3 months (OR = 1.67, 95% CI = 1.14-2.45); injection of heroin mixed with methamphetamine in the last 3 months (OR = 1.74, 95% CI = 1.15-2.65); ever tested for hepatitis B or C (OR = 1.66 per year, CI = 1.09-2.54) and ever having witnessed another person overdose (OR = 2.89, 95% CI = 1.76-4.73). CONCLUSIONS: Individuals with high levels of incarceration are at great risk of overdose, and prison or jail should be considered a primary intervention site. Further research on the role of cocaine and amphetamine in heroin-related overdose is indicated.     

Factors related to correctional facility incarceration among active injection drug users in Baltimore, MD

AIM: We investigated the moderating effect of impulse control on the association between drug use and incarceration among active injection drug users (IDU). METHODS: The study sample consisted of 282 IDUs aged 15-50 years from the Baltimore metropolitan region who reported injection drug use within the past 6 months and indicated that heroin or speedball was their drug of choice. Impulse control was measured using commission error standardized scores from the Test of Variables of Attention (TOVA). Incarceration was obtained using self-reported lifetime history of incarceration in correctional facilities. RESULTS: Findings indicated that impulse control moderated the association between years of injection drug use and incarceration in correctional facilities adjusting for ethnicity, gender, estimated pre-morbid intelligence, and age of first injection use. Specifically, among individuals who were intact in impulse control, four or more years of injection drug use was associated with incarceration (AOR=4.97, 95% CI: 2.02-12.23). This finding was not observed among individuals with impaired impulse control (AOR=0.57, 95% CI: 0.10-3.23). Furthermore, impulse control moderated the association between regular cocaine use and incarceration. Among individuals who had a history of cocaine use, individuals with low impulse control but not impaired were more likely to have reported time in a correctional facility (AOR=6.28, 95% CI: 1.68-23.60). There was no association among individuals with impaired or intact impulse control. CONCLUSION: Results highlight the importance of considering cognitive measures of impulse control in addressing negative outcomes associated with drug use.     

Methadone use among HIV-positive injection drug users in a Canadian setting

We examined methadone maintenance therapy (MMT) use among HIV-positive injection drug users (IDU) in Vancouver. Among 353 participants, 199 (56.3%) were on MMT at baseline, and 48 initiated MMT during follow-up. Female gender (adjusted odds ratio [AOR] = 1.73, 95% confidence interval [CI] = 1.14–2.62) and antiretroviral therapy use (AOR = 2.04, 95% CI = 1.46–2.86) were positively associated with MMT use, whereas frequent heroin injection (AOR = 0.34, 95% CI = 0.23–0.50), public injection (AOR = 0.76, 95% CI = 0.59–0.97), syringe borrowing (AOR = 0.54, 95% CI = 0.32–0.90), and nonfatal overdose (AOR = 0.58, 95% CI = 0.36–0.92) were negatively associated with MMT use. The rate of discontinuation of MMT was 12.46 (95% CI = 8.28–18.00) per 100 person years. Frequent heroin use (adjusted hazards ratio = 4.49, 95%CI = 1.81–11.13) was positively associated with subsequent discontinuation of MMT. These findings demonstrate the benefits of MMT among HIV-positive IDU and the need to improve access to and retention in MMT.     

Pathways between ecstasy initiation and other drug use

This study aims to shed light on drug use pathways associated with ecstasy use initiation. Data from 54,573 respondents aged 12-21 years old from the 2002-2003 National Survey on Drug Use and Health (NSDUH) public use data files were analyzed via Cox proportional hazards models with time-dependent covariates. Our findings showed that marijuana, cocaine, and heroin were significant independent predictors of subsequent ecstasy use. Earlier ecstasy initiation was significantly associated with subsequent other illegal drug initiation (marijuana, cocaine and heroin). The strength of the association was greater for the pathway from earlier marijuana initiation to subsequent ecstasy initiation as compared to the pathway in the opposite direction. The pathway from earlier ecstasy initiation to subsequent cocaine and heroin initiation was also stronger as compared to pathways in the opposite directions. Pathways between ecstasy initiation and marijuana, cocaine and heroin initiation seem to be independent of the association between drug use and psychiatric symptoms/deviant behaviors. Ecstasy initiation seems to play a role in the subsequent initiation of cocaine and heroin.     

Sexual Risk and HIV Infection Among Drug Users in New York City: A Pilot Study

Measures of sexual health were assessed during 2008–2009 in a New York City sample of 102 injection and noninjection users of heroin, cocaine, or crack. There was considerable overlap and transitioning between crack smoking and injecting. Crack users were also significantly more likely to be gay, lesbian, or bisexual than other drug users. In multivariate analysis, HIV infection was independently associated with crack use and with being gay or bisexual. In New York City, HIV prevention for drug users has focused on syringe access, safe injection, and drug user treatment, but further progress in HIV control will require strategies to address sexual health among people who use drugs. The study's limitations are noted.     

Association of sex, hygiene and drug equipment sharing with hepatitis C virus infection among non-injecting drug users in New York City

BACKGROUND: Hepatitis C virus (HCV) rates are higher in non-injecting drug users (NIDUs) than general population estimates. Whether this elevated HCV rate is due to drug use or other putative risk behaviors remains unclear. METHODS: Recent non-injection drug users of heroin, crack and/or cocaine were street-recruited from 2000 to 2003 and underwent an interview and venipuncture for HCV antibody assays. Multiple logistic regression analyses were used to assess correlates for HCV infection. RESULTS: Of 740 enrollees, 3.9% were HCV positive. The median age (intraquartile range) was 30 (35-24) years, 70% were male and 90% were Black or Hispanic. After adjustment, HCV seropositives were significantly more likely than seronegatives to be older than 30 [adjusted odds ratio (AOR)=5.71], tattooed by a friend/relative/acquaintance [AOR=3.61] and know someone with HCV [AOR=4.29], but were less likely to have shared nail or hair clippers, razors or a toothbrush [AOR=0.32]. CONCLUSIONS: Non-commercial tattooing may be a mode of HCV transmission among NIDUs and education on the potential risk in using non-sterile tattooing equipment should be targeted toward this population. While no evidence was found for HCV transmission through NIDU equipment sharing or sexual risk behavior, further research is still warranted.     

Criminal justice involvement of crack cocaine users in the city of Rio de Janeiro and Greater Metropolitan Area: Implications for public health and the public security agenda

BackgroundThe international literature has expressed different and sometimes contrasting perspectives when addressing criminal involvement by crack cocaine users, highlighting psychopharmacological aspects, the cycles of craving and pressing economic need, and the interplay with overall deprivation and structural violence. The current study aims to identify variables associated with the arrest and imprisonment of regular crack cocaine users.MethodsInterviewees were recruited from open drug scenes in the city of Rio de Janeiro and Greater Metropolitan Area from September 2011 to June 2013. Multilevel logistic regression models were fitted to the data.ResultsMost of the recruited crack cocaine users were male (78.2% [95%CI: 76.3–79.4]), 18–30 years old (64.7% [95%CI: 62.5–66.2]), non-white (92.9% [95%CI: 91.2–93.4]), single (68.9% [95%CI: 66.8–70.3]), and with 0–7 years of schooling (70.6% [95%CI: 68.5–71.9]). Factors independently associated with arrest were history of inpatient addiction treatment (adjOR 4.31 [95%CI: 1.70–11.32]); male gender (adjOR 2.05 [95%CI: 1.40–3.04); polydrug use (adjOR 1.82 [95%CI: 1.32–2.51]); and 0 to 7 years of schooling (adjOR 1.64 [95%CI: 1.17–2.32]). As for the outcome variable lifetime history of incarceration, the independently associated factors were: male gender (adjOR 2.47 [95%CI: 1.74–3.55]) and longer use of crack cocaine and related substances (e.g., free base and local varieties/denominations of coca products) (adjOR 1.05 [95%CI: 1.01–1.10]).ConclusionThe study’s findings support the use of comprehensive multisector interventions, integrating health promotion and mental health rehabilitation, access to quality education, and management of combined/concomitant use of different substances to reduce and/or prevent criminal involvement by individuals that use crack cocaine and other substances, as well as to prevent/manage relapse.     

HIV seroprevalence among drug users: an analysis of selected variables based on 10 years of data collection in Porto Alegre, Brazil

Data from five studies were pooled to describe associations between drug use and HIV. The Risk Assessment. Battery in Porto Alegre, Brazil, was used to collect data from 1449 subjects in 5 separate studies conducted between 1995 and 2004. The subjects were divided into categories based on their pattern of drug use: (1) injection drug users (IDUs), (2) crack smokers, (3) frequent drug users, and (4) infrequent cocaine/alcohol/marijuana users. The sample consisted primarily of young males with low education and income levels. Half of the subjects reported frequent condom use, and exchanges involving drugs, sex, and money were infrequent (although more common in groups 1 and 2). The overall seroprevalence was 20.6%, and the prevalence was different across the four groups, showing a linear decrease from group 1 (57.1%) to group 4 (11.7%). The IDU and crack-smoking groups showed similarities in their risk levels when compared with the other two groups, and individuals in group 1, 2, and 3 were more likely to report having had four or more sex partners. After controlling for all other risk factors, IDU, males having sex with males, and crack use were highly associated with HIV (OR 7.30, 95% CI: 5.10.10.40; OR 3.04, 95%CI: 1.89,4.80; OR 2.03, 95%CI: 1.40, 2.92, respectively). The findings confirm that poverty, low education, and IDU remain risk factors for HIV in Porto Alegre, Brazil, and the study identities crack smoking as a new risk factor.     

Prevalence and correlates of suicidal ideation among young injection vs. noninjection drug users

The objective of this study was to identify correlates of suicidal ideation and to examine the hypothesis that injection drug users (IDUs) were more likely to report suicidal ideation than noninjection drug users (NIDUs). Participants included IDUs (n = 244) and NIDUs (n = 73) from Baltimore, Maryland, aged 15-30 who began snorting or smoking heroin or cocaine/crack (NIDUs) or injecting drugs (IDUs) within the past 5 years who were recruited between August 2000 and March 2002. Among the 317 participants, 42% were female, 59% were white, and median age was 24. The prevalence of suicidal ideation was 27%. IDUs were more likely to report suicidal ideation than NIDUs (31% vs. 14%, p = 0.003). Adjusting for age, gender, and race, IDUs were 2.4 times more likely than NIDUs to report suicidal ideation [95% Confidence Interval (CI): 1.1-5.2]. However, on further adjustment for homelessness, depressive symptoms, and gay/lesbian/bisexual identity, IDU status was no longer independently associated with suicidal ideation. These results suggest that factors associated with injection drug users' lifestyles and mental health status may account for the higher prevalence of suicidal ideation in IDUs vs. NIDUs. Further study into these associations is warranted in identifying avenues for suicide prevention among these populations.     

The association between cigarette smoking and drug abuse in the United States

Cigarette smoking has been identified as an independent risk factor for many human diseases. However, the association between cigarette smoking and illegal drug use has not been thoroughly investigated. We have analyzed the 1994 National Household Survey on Drug Abuse to clarify whether cigarette smoking has any effect on the initiation of illegal drug use. Data from 17,809 respondents completing the 1994 "new" (1994-B) questionnaire were analyzed. Logistic regression analyses were performed with the use of statistical package SUDAAN, taking into consideration the multistage sampling design. The results show that those who had smoked cigarettes were far more likely to use cocaine (OR = 7.5; 95% CI: 5.7-9.9), heroin (OR = 16.0; 95% CI: 6.8-37.9), crack (OR = 13.9; 95% CI: 7.9-24.5) and marijuana (OR = 7.3; 95% CI: 6.2-8.7). The associations are consistent across age-strata and remain after adjusting for race and gender. This study suggests that cigarette smoking may be a gateway drug to illegal drug use.