Research Findings - Epidemiology and Etiology Research
Pathways from Cannabis Availability and Initiation to Abuse
Although previous twin studies have modeled the association between drug initiation and abuse, none has included the obvious risk factor of drug availability. The aim of this study is to determine whether the genetic and environmental risk factors for cannabis availability also generate variation in cannabis initiation and/or progression to DSM-IV symptoms of abuse. The authors used multi-stage modeling, also known as causal-common-contingent (CCC) analysis, to partition the genetic and environmental factors into common and stage-specific components. This report is based on data collected from 1772 adult males ages 24-62 from the Mid Atlantic Twin Registry. The twins participated in two structured interviews which included clinical and non-clinical measures of cannabis abuse as well as retrospective assessments of perceived cannabis availability between ages 8 and 25 years. Cannabis availability explained almost all the shared environmental risks in cannabis initiation and abuse. The influence of availability on the symptoms of abuse was indirect and mediated entirely by cannabis initiation. These findings have begun to elucidate the causal processes underlying the liability to drug use and abuse in terms of putative risk factors. Specifically, they show that the latent shared environmental factors in cannabis initiation and abuse can be explained by measured aspects of the shared environment--those responsible for variation in cannabis availability. Gillespie N, Neale M, Kendler K. Pathways to cannabis abuse: a multi-stage model from cannabis availability, cannabis initiation and progression to abuse. Addiction. 2009;104(3):430-8.
Drug Exposure Opportunities and Use Patterns among College Students: Results of a Longitudinal Prospective Cohort Study
Underage drinking and drug use among college students are major public health concerns, yet few studies have examined these behaviors and their associated risk factors and consequences prospectively. This paper describes the sampling and recruitment methods of a longitudinal study of 1253 college students at a large, mid-Atlantic university. Incoming first-year students were screened during the unique window between high school and college in order to oversample drug users for longitudinal follow-up. Intensive recruitment strategies yielded a 95% cumulative response rate in annual interviews and semiannual surveys. The authors report preliminary results on exposure opportunity, lifetime prevalence, initiation, continuation, and cessation of substance use for alcohol, tobacco, and 10 illicit and prescription drugs during the first 2 years of college. Findings suggest that although some substance use represents a continuation of patterns initiated in high school, exposure opportunity and initiation of substance use frequently occur in college. Implications for prevention and early intervention are discussed. Arria A, Caldeira K, O 'Grady K, Vincent K, Fitzelle D, Johnson E, Wish E. Drug exposure opportunities and use patterns among college students: results of a longitudinal prospective cohort study. Subst Abuse. 2008;29(4):19-38.
Some Moms Quit Cigarettes, Marijuana, & Alcohol during Pregnancy, but Dads Don't
With the possible exception of cigarette smoking, little attention is paid to substance abuse among men whose partner is pregnant. An understanding of men's patterns of substance use during their partner's pregnancy is necessary to identify critical periods for intervention to reduce children's exposure to paternal substance use. This study examined the relationship between pregnancy or partner's pregnancy and patterns of binge drinking, cigarette use, and marijuana use, desistance, and return to use over a 3-year period from age 21 to 24 years. Data were drawn from the Seattle Social Development Project, a longitudinal study of prosocial and antisocial behavior. 808 (412 male, 396 female) students entering 5th grade in participating schools in the fall of 1985 that consented to participate constitute the sample. Interviews were conducted yearly from ages 10 to 16, at ages 18, 21, and 24. The data used in this study were obtained from age 24 data. Event history calendars were administered at age 24 and were retrospective to 21 years. To provide temporal context, a series of questions about live events, work, and school history were asked. Reports of events were probed to identify the month and year in which they occurred, and repeated events were probed to identify the month and year of each occurrence. Pregnancy was deduced based on the birth date of the child. Men were as likely to binge drink during their partner's pregnancy as they were when their partner was not pregnant. In contrast, women were significantly less likely to binge drink during pregnancy compared with before or after pregnancy. Men were less likely to smoke when their partner was pregnant than they were when their partner was not pregnant. Similarly, women were less likely to smoke during pregnancy than they were before or after pregnancy. Men were as likely to use marijuana during their partner's pregnancy as they were when their partner was not pregnant. Women were less likely to use marijuana when they were pregnant than when they were not pregnant. Because of a return to cigarette smoking among men and to all three forms of substance use among women occurs so soon after birth, the first few months postpartum may provide a critical opportunity for intervention. Men's binge drinking and marijuana use were unaffected by their partner's pregnancy or by the birth of their child suggesting the importance of reaching new fathers-to-be with messages about the importance of stopping substance use during their partner's pregnancy. Reductions in substance use among fathers both during pregnancy and after the birth of their child would likely increase the probability that mothers will desist from substance use during pregnancy, decrease the probability that mothers will relapse to use postpartum, and reduce children's exposure to harmful substance use in the home environment. The first few months postpartum also represent an opportunity for health care practitioners to educate new fathers about the potential effects of their substance-use behavior on their child's development and on the substance-use behavior of their partner. Bailey JA, Hill KG, Hawkins JD, Catalano RF, Abbott RD. Men's and women's patterns of substance use around pregnancy. Birth. 2008;35(1):50-9.
Peer Group Deviance and Cannabis Use: Modeling the Association
Peer group deviance (PGD) is linked strongly to liability to drug use, including cannabis. The aim was to model the genetic and environmental association, including direction of causation, between PGD and cannabis use (CU). Results were based on 1736 to 1765 adult males from the Mid-Atlantic Twin Registry with complete CU and PGD data measured retrospectively from 1994-2004, at three time-intervals between 15 and 25 years using a life-history calendar. At all ages, multivariate modeling showed that familial aggregation in PGD was explained by a combination of additive genetic and shared environmental effects. Moreover, the significant PGD-CU association was best explained by a CU-->PGD causal model in which large portions of the additive genetic (50-78%) and shared environmental variance (25-73%) in PGD were explained by CU. These findings question the assumption that PGD was an environmental, upstream risk factor for CU. Rather, they suggest that the liability to affiliate with deviant peers is explained more clearly by a combination of genetic and environmental factors that are indexed by CU which sits as a ''risk indicator '' in the causal pathway between genetic and environmental risks and the expression of PGD. This is consistent with a process of social selection by which the genetic and environmental risks in CU largely drive the propensity to affiliate with deviant peers. Gillespie N, Neale M, Jacobson K, Kendler K. Modeling the genetic and environmental association between peer group deviance and cannabis use in male twins. Addiction. 2009;104(3):420-9.
Needle Exchange and Sexual Risk Behaviors among a Cohort of Injection Drug Users in Chicago, Illinois
Researchers examined the impact of a needle exchange program (NEP) on sexual risk behaviors of injecting drug users (IDUs). Between 1997 and 2000, 889 IDUs in Chicago were recruited from NEPs and an area with no NEP into a cohort study. They were interviewed and tested for HIV at baseline and 3 annual follow-up visits. Random-effect logistic models were used to compare NEP users and nonusers regarding the number of sex partners, number of unprotected sex acts, and frequency of condom use. Compared to NEP nonusers, NEP users had a similar number of sex partners over time, but had 49% higher odds of using condoms with their main partners (p = 0.047). At baseline, there was no difference between NEP users and nonusers in episodes of vaginal intercourse, but over time the odds of having a higher number of unprotected instances of vaginal intercourse were reduced by 26% per year for NEP users but only 10% per year for nonusers (p = 0.02). These findings suggest that NEP participation may help to reduce the absolute risk of HIV sexual transmission. Huo D, Ouellet L. Needle exchange and sexual risk behaviors among a cohort of injection drug users in Chicago, Illinois. Sex Transm Dis. 2009;36(1):35-40.
Methamphetamine Use Trends among Street-Recruited Gay and Bisexual Males, from 1999 to 2007
Street outreach encounters were used to collect data of reported alcohol and other drug use among gay and bisexual males (N = 11,375) in Hollywood and West Hollywood, California over a 9-year period from January 1999 to December 2007. Analyses were conducted to assess demographic data, self-reported HIV status, and frequency of alcohol and other drug use. Participants averaged 32.3 (SD = 7.7) years, slightly over half were Caucasian/white (53%), and most were identified as gay (85.8%). Self-reported HIV seroprevalence was 20.7%. Observations began January to June 1999, with 46.0% reporting recent methamphetamine use, and ended July to December 2007, with 24.8% reporting recent use of methamphetamine. Percent reporting methamphetamine use peaked in the first half of 2002 at 53% and dipped to a low of 11.1% in the second half of 2006. Findings demonstrate the common use of methamphetamine over the observation period in this high-risk group even in the face of a recent decline in reported use. These data also indicate the need for ongoing methamphetamine abuse and HIV-prevention interventions in this particular high-risk population. Reback C, Shoptaw S, Grella C. Methamphetamine use trends among street-recruited gay and bisexual males, from 1999 to 2007. J Urban Health. 2008;85(6):874-9.
Intranasal Transmission of Hepatitis C Virus: Virological and Clinical Evidence
Intranasal transmission of hepatitis C virus (HCV) via contaminated drug-sniffing implements is a potential but unconfirmed source of viral infection. Researchers were able to demonstrate the virological plausibility of intranasal transmission by confirming that blood and HCV RNA are present in the nasal secretions and drug-sniffing implements of HCV-infected intranasal drug users recruited from a community health clinic in New York City. They conducted an interdisciplinary mixed methods cross-section study involving 86 subjects. Based on 20 qualitative interviews, a quantitative HCV risk survey was then developed and administered to 60 HCV infected drug sniffers. Nasal swabs and drug sniffing implements were collected and tested for the presence of occult blood and HCV RNA. A clinical nasal examination and assessment were also administered. Occult blood was detected in 74% of nasal swabs and 8% of sniffing implements. HCV RNA was detected in 13% of nasal swabs and 5% of sniffing implements. Nasal pathology among chronic drug sniffers was moderate to high, and included epistaxis, rhinitis, rhinorrhea, mucosal lesions, and nasal septal perforations. These findings suggest that intranasal transmission of HCV through contaminated drug-sniffing implements, such as straws or spoons shared by intranasal drug users, may account for the estimated 20% of HCV cases that are otherwise not explained by known primary routes of transmission (ie, injection drug use). Aaron S, McMahon J, Milano D, Torres L, Clatts M, Tortu S, Mildvan D, Simm M. Intranasal transmission of hepatitis C virus: virological and clinical evidence. Clin Infect Dis. 2008;47(7):931-4.
National Comorbidity Survey Replication Adolescent Supplement: I. Background and Measures
This article presents an overview of the background and measures used in the National Comorbidity Survey Replication Adolescent Supplement (NCS-R Adol Supplement). The NCS-R Adol Supplement is a national psychiatric epidemiological survey of adolescents aged 13 to 17 years. The NCS-R Adol Supplement was designed to provide the first nationally representative estimates of the prevalence, correlates, and patterns of service use for DSM-IV mental disorders among U.S. adolescents and to lay the groundwork for follow-up studies of risk and protective factors, consequences, and early expressions of adult mental disorders. The core NCS-R Adol Supplement diagnostic interview, the World Health Organization Composite International Diagnostic Interview, is a fully structured research diagnostic interview designed for use by trained lay interviewers. A multiconstruct, multimethod, and multi-informant battery was also included to assess risk and protective factors and barriers to service use. Design limitations due to the NCS-R Adol Supplement evolving as a supplement to an ongoing survey of mental disorders of U.S. adults include restricted age range of youths, cross-sectional assessment, and lack of full parental/surrogate informant reports on youth mental disorders and correlates. Despite these limitations, the NCS-R Adol Supplement contains unparalleled information that can be used to generate national estimates of prevalence and correlates of adolescent mental disorders, risk and protective factors, patterns of service use, and barriers to receiving treatment for these disorders. The retrospective NCS-R Adol Supplement data on the development of psychopathology can additionally complement data from longitudinal studies based on more geographically restricted samples and serve as a useful baseline for future prospective studies of the onset and progression of mental disorders in adulthood. Merikangas KR, Avenevoli S, Costello EJ, Koretz D, Kessler RC. Journal of the American Academy of Child and Adolescent Psychiatry. 2009; Feb 25. [Epub ahead of print].
National Comorbidity Survey Replication Adolescent Supplement: II. Overview and Design
This article presents an overview of the design and field procedures of the National Comorbidity Survey Replication Adolescent Supplement (NCS-R Adol Supplement). The NCS-R Adol Supplement is a nationally representative face-to-face household survey of the prevalence and correlates of DSM-IV mental disorders among U.S. adolescents (aged 13-17 years) that was performed between February 2001 and January 2004 by the Survey Research Center of the Institute for Social Research at the University of Michigan. The sample was based on a dual-frame design that included 904 adolescent residents of the households that participated in the National Comorbidity Survey Replication (response rate 85.9%) and 9,244 adolescent students selected from a representative sample of 320 schools in the same nationally representative sample of counties as the National Comorbidity Survey Replication (response rate 74.7%). Comparisons of sample and population distributions on census sociodemographic variables and, in the school sample, school characteristics documented only minor differences that were corrected with poststratification weighting. Comparisons of DSM-IV disorder prevalence estimates among household versus school sample respondents in counties that differed in the use of replacement schools for originally selected schools that refused to participate showed that the use of replacement schools did not introduce bias into prevalence estimates. In brief, the NCS-R Adol Supplement is a rich nationally representative dataset that will substantially increase understanding of the mental health and well-being of adolescents in the United States. Kessler RC, Avenevoli S, Costello EJ, Green JG, Gruber MJ, Heeringa S, Merikangas KR, Pennell BE, Sampson NA, Zaslavsky AM. Journal of the American Academy of Child and Adolescent Psychiatry. 2009; Feb 25. [Epub ahead of print].
National Comorbidity Survey Replication Adolescent Supplement: III. Concordance of DSM-IV/CIDI Diagnoses With Clinical Reassessments
This article reports results of the clinical reappraisal study of lifetime DSM-IV diagnoses based on the fully structured lay-administered World Health Organization Composite International Diagnostic Interview (CIDI) Version 3.0 in the U.S. National Comorbidity Survey Replication Adolescent Supplement (NCS-R Adol Supplement). Blinded clinical reappraisal interviews with a probability subsample of 347 NCS-R Adol Supplement respondents were administered using the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS) as the gold standard. The DSM-IV/CIDI cases were oversampled, and the clinical reappraisal sample was weighted to adjust for this oversampling. The results show good aggregate consistency was found between CIDI and K-SADS prevalence estimates, although CIDI estimates were meaningfully higher than K-SADS estimates for specific phobia (51.2%) and oppositional defiant disorder (38.7%). Estimated prevalence of any disorder, in comparison, was only slightly higher in the CIDI than K-SADS (8.3%). Strong individual-level CIDI versus K-SADS concordance was found for most diagnoses. Area under the receiver operating characteristic curve, a measure of classification accuracy not influenced by prevalence, was 0.88 for any anxiety disorder, 0.89 for any mood disorder, 0.84 for any disruptive behavior disorder, 0.94 for any substance disorder, and 0.87 for any disorder. Although area under the receiver operating characteristic curve was unacceptably low for alcohol dependence and bipolar I and II disorders, these problems were resolved by aggregation with alcohol abuse and bipolar I disorder, respectively. Logistic regression analysis documented that consideration of CIDI symptom-level data significantly improved prediction of some K-SADS diagnoses. In conclusion, these results document that the diagnoses made in the NCS-R Adol Supplement based on the CIDI have generally good concordance with blinded clinical diagnoses. Kessler RC, Avenevoli S, Green J, Gruber MJ, Guyer M, He Y, Jin R, Kaufman J, Sampson NA, Zaslavsky AM, Merikangas KR. Journal of the American Academy of Child and Adolescent Psychiatry. 2009;48(4):386-39.
Validity of Self-Reported Adherence among Injection Drug Users
In Vancouver, the availability of prescription refill data for all HIV-infected individuals plus a prospective cohort of injection drug users (IDUs participating in the Vancouver Injection Drug Use Study or VIDUS) permitted an examination of the validity of self-reported HAART adherence among IDUs. Self-reported HAART adherence among VIDUS participants was compared with pharmacy refill rates from the British Columbia Drug Treatment Program database. Pearson's correlation coefficient and Pearson's chi(2) test were used to assess associations between adherence as measured by self-report and pharmacy refill data. Among 88 HIV-infected IDUs, 48 (55%) had an adherence rate of >/=75% as measured by pharmacy refill adherence, whereas 81 (92%) had an adherence rate of >/=75% as measured by self-report. Self-reported adherence was not statistically associated with pharmacy refill adherence (P >.1). These findings suggest that the validity of self-report HAART adherence measures may be limited when applied to community-recruited IDUs. Kerr T, Hogg R, Yip B, Tyndall M, Montaner J, Wood E. Validity of Self-Reported Adherence among Injection Drug Users. J Int Assoc Physicians AIDS Care (Chic Ill). 2008;7(4):157-9.
Hallucinogen Use Disorders among Adult Users of MDMA and Other Hallucinogens
The authors investigated the prevalence, patterns, and correlates of past-year DSM-IV hallucinogen use disorders (HUDs) among past-year users of MDMA and other hallucinogens utilizing data from 37,227 subjects age 18 and older who participated in the 2005 National Survey on Drug Use and Health. Users were categorized as MDMA users and other hallucinogen users. Overall, one in five (20%) MDMA users and about one in six (16%) other hallucinogen users reported at least one clinical feature of HUDs. Among MDMA users, prevalence of hallucinogen abuse, subthreshold dependence, and dependence was 4.9%, 11.9%, and 3.6%, respectively. The majority with hallucinogen abuse displayed subthreshold dependence. Most with hallucinogen dependence exhibited abuse. These findings suggest that subthreshold hallucinogen dependence is relatively prevalent and represents a clinically important subgroup that warrants future research and consideration in a major diagnostic classification system. Wu L, Ringwalt C, Mannelli P, Patkar A. Hallucinogen Use Disorders among adult users of MDMA and other hallucinogens. Am J Addict. 2008;17(5):354-63.
Group Sex Events and HIV/STI Risk in an Urban Network
This study sought to describe: (a) the prevalence and individual and network characteristics of "group sex events" (GSEs) and GSE attendees; and (b) HIV/sexually transmitted infection (STI) discordance among respondents who report they went to a GSE together. In a sociometric network study of risk partners (defined as sexual partners, persons with whom respondents attended a GSE, or drug injection partners) in Brooklyn, NY, researchers recruited a high-risk sample of 465 adults. Respondents reported on GSE attendance, the characteristics of GSEs, and their own and others' behaviors at GSEs. Sera and urines were collected, and STI prevalence was assayed. Of the 465 participants, 36% had attended a GSE in the last year, 26% had sex during the most recent of these GSEs, and 13% had unprotected sex there. Certain subgroups (hard drug users, MSM, women who have sex with women, and sex workers) were more likely to attend and more likely to engage in risk behaviors at these events. Among 90 GSE dyads in which at least 1 partner named the other as someone with whom they attended a GSE in the previous 3 months, STI/HIV discordance was common [herpes simplex virus (HSV-2): 45% of dyads, HIV: 12% of dyads, and chlamydia: 21% of dyads]. Many GSEs had 10 or more participants, and multiple partnerships at GSEs were common. High attendance rates at GSEs among members of large networks may increase community vulnerability to STI/HIV, particularly because network data show that almost all members of a large sociometric risk network either had sex with a GSE attendee or had sex with someone who had sex with a GSE attendee. Self-reported GSE attendance and participation were common among this high-risk sample. STI/HIV discordance among GSE attendees was also high, underscoring the potential transmission risk associated with GSEs. Research on sexual behaviors should routinely incorporate measures of GSE behaviors to improve the standard research protocol. Effective interventions are needed to reduce risks and avert transmission of STI/HIV at GSEs. Friedman S, Bolyard M, Khan M, Maslow C, Sandoval M, Mateu-Gelabert P, Krauss B, Aral S. Group Events and HIV/STI Risk in an Urban Network. J Acquir Immune Defic Syndr. 2008;49(4):440-6.
Long-term Effectiveness of Diagnosing and Treating Latent Tuberculosis Infection in a Cohort of HIV-infected and At-Risk Injection Drug Users
Between 1990 and 1998, tuberculin skin tests (TST) and isoniazid preventive therapy (IPT) were provided to injection drug users participating in the AIDS Linked to the Intravenous Experiences (ALIVE) cohort. A registry match was conducted with the ALIVE cohort database and the Maryland State Department of Health and Mental Hygiene tuberculosis registry. Of 2010 participants, 1753 (74%) had a TST placed and read; 536 (31%) were positive. TST positivity was 16% in HIV positives; 39% in HIV negatives (P<0.01). Overall, 299 (56%) TST reactors started IPT; 165 (55%) completed 6 months. Three tuberculosis (TB) cases were diagnosed among HIV negatives (incidence rate=0.16/1000 person-years); 19 among HIV positives (1.94/1000 person-years; incidence rate ratio=12.3 (3.61-64.70). Within the entire cohort, TB rates were 0.81 per 1000 person-years for those not receiving IPT, 0.48 per 1000 person-years for those receiving any IPT, 0.29 per 1000 person-years for those completing at least 30 days, and 0 per 1000 person-years for completers. Ten cases of TB occurred in HIV-infected individuals with negative TSTs. IPT was associated with protection against TB, but uptake was modest. Although it is likely that TB incidence would have increased, especially in HIV-positive subjects, if the IPT program had not occurred, more significant declines in TB incidence in this population will require improved methods for ensuring uptake and completion of IPT and preventing disease in TST-negative individuals. Golub J, Astemborski J, Ahmed M, Cronin W, Mehta S, Kirk G, Vlahov D, Chaisson R. Long-term effectiveness of diagnosing and treating latent tuberculosis infection in a cohort of HIV-infected and at-risk injection drug users. J Acquir Immune Defic Syndr. 2008;49(5):532-7.
Heavy Drinking and Polydrug Use among College Students
Excessive alcohol consumption is a serious problem on college campuses but may not be adequately captured by traditional methods of defining binge drinking. This study examined a new approach to categorizing alcohol use and its relationship with illicit drug use. A survey was administered to 484 college students ages 18 to 25. Drinkers were divided into three groups based on the number of typical drinks consumed per day: "light"-1 to 4 (n=182); "moderate"-5 to 9 (n=173); and "heavy"-10+ (n=56). Heavy drinkers could be differentiated from moderate and light drinkers on age of onset of alcohol use, illicit drug use, and frequency of illicit drug use. A binary categorization of "binge" vs. "nonbinge" drinking may obscure important differences within binge drinkers. These findings have implications for prevention, as well as clinical risk assessment of college student drinkers for adverse consequences of concomitant alcohol and illicit drug consumption. O'Grady KE, Arria AM, Fitzelle DM, Wish ED. Heavy drinking and polydrug use among college students. J Drug Issues. 2008;38(2):445-66.
Disorders Among Inhalant Users
This study examined the prevalence, correlates, and age of onset of DSM-IV substance use disorders (SUDs) among adult inhalant users. Analyses were based on structured psychiatric interviews of a nationally representative sample of 43,093 US adults. The lifetime prevalence of SUDs among adult inhalant users was 96%. Alcohol (87%), marijuana (68%), nicotine (58%), cocaine (35%), hallucinogen (31%), and stimulant (28%) use disorders were more prevalent than inhalant use disorders (19%). An estimated 62% of inhalant users met criteria for a past-year SUD. Less education, residence in non-metropolitan areas, early onset of inhalant use, and a history of substance abuse treatment were associated with increased odds of having an inhalant use disorder. Inhalant users who were under age 30 or who were members of families with low incomes had increased odds of having nicotine dependence and an alcohol or drug use disorder in the past year. Compared with substance users without a history of inhalant use, inhalant users, on average, initiated use of cigarettes, alcohol, and almost all other drugs at younger ages, and had a higher lifetime prevalence of nicotine, alcohol, and any drug use disorder. These findings demonstrate that lifetime and past-year SUDs are prevalent among adults with a history of inhalant use. Wu L, Howard M, Pilowsky D. Substance use disorders among inhalant users: results from the National Epidemiologic Survey on Alcohol and Related Conditions. Addict Behav. 2008;33(7):968-73.
Childhood Maltreatment and the Development of Relational and Physical Aggression: The Importance of a Gender-informed Approach
The researchers examined the associations between maltreatment and aggression using a gender-informed approach among a cohort of inner-city youth attending a summer day camp. Peer ratings, peer nominations, and counselor reports of aggression were collected on 211 maltreated and 199 nonmaltreated youth (median age = 9.9 years). Maltreatment was associated with aggressive conduct; however, these effects were qualified by gender, maltreatment subtype, and the form of aggression under investigation. Findings revealed that maltreatment was associated with physical aggression for boys and relational aggression for girls. Physical abuse was associated with physically aggressive behaviors, but sexual abuse predicted relational aggression for girls only. These findings suggest that investigating the interaction between familial risk and gender is important in understanding aggressive behaviors of boys and girls. Cullerton-Sen C, Cassidy A, Murray-Close D, Cicchetti D, Crick N, Rogosch F. Childhood maltreatment and the development of relational and physical aggression: the importance of a gender-informed approach. Child Dev. 2008;79(6):1736-51.
A Meta-Analysis of the Hepatitis C Virus Distribution in Diverse Racial/Ethnic Drug Injector Groups
Hepatitis C virus (HCV) is mostly transmitted through blood-to-blood contact during injection drug use via shared contaminated syringes/needles or injection paraphernalia. This paper used meta-analytic methods to assess whether HCV prevalence and incidence varied across different racial/ethnic groups of injection drug users (IDUs) sampled internationally. The 29 prevalence and 11 incidence studies identified as part of the HCV Synthesis Project were categorized into subgroups based on similar racial/ethnic comparisons. The effect estimate used was the odds or risk ratio comparing HCV prevalence or incidence rates in racial/ethnic minority groups versus those of majority status. For prevalence studies, the clearest disparity in HCV status was observed in the Canadian and Australian Aboriginal versus White comparison, followed by the US non-White versus White categories. Overall, Hispanic IDUs had greater HCV prevalence, and HCV prevalence in African-Americans was not significantly greater than that of Whites in the US. Aboriginal groups showed higher HCV seroconversion rates when compared to others, and African-Americans had lower seroconversion rates compared to other IDUs in the US. The findings suggest that certain minority groups have elevated HCV rates in comparison to other IDUs, which may be a consequence of stigma, discrimination, different risk behaviors or decreased access to health care, services and preventive education. Future research should seek to explicitly explore and explain racial/ethnic variations in HCV prevalence and incidence, and define the groups more precisely to allow for more accurate detection of possible racial/ethnic differences in HCV rates. Lelutiu-Weinberger C, Pouget E, Des Jarlais D, Cooper H, Scheinmann R, Stern R, Strauss S, Hagan H. A meta-analysis of the hepatitis C virus distribution in diverse racial/ethnic drug injector groups. Soc Sci Med. 2009;68(3):579-90.
Nonadherence Increases the Risk of Hospitalization among HIV-infected Antiretroviral Naive Patients Started on HAART
Since the advent of highly active antiretroviral therapy (HAART), AIDS-related hospitalizations have decreased. The objective of this study was to assess the impact of adherence on hospitalization among antiretroviral-na•ve HIV-infected persons initiating HAART. Analysis was based on a cohort of individuals initiating HAART between 1996 and 2001. The primary outcome was hospitalization for one or more days. Survival methods were used to assess the impact of adherence on hospitalization. Of 1605 eligible participants, 672 (42%) were hospitalized for one or more days after initiating HAART. Median adherence levels were 92 (IQR: 58, 100) and 100 (IQR: 83, 100) among those ever and never hospitalized, respectively. After controlling for confounders, those with <95% adherence had 1.88 times (95% CI: 1.60, 2.21) higher risk for hospitalization. These findings indicate that suboptimal adherence among HIV-infected patients taking HAART predicts hospitalization. Identifying and addressing the factors that contribute to poor adherence early in treatment could improve patient care and lower hospitalization costs. Fielden S, Rusch M, Yip B, Wood E, Shannon K, Levy A, Montaner J, Hogg R. Nonadherence increases the risk of hospitalization among HIV-infected antiretroviral naive patients started on HAART. J Int Assoc Physicians AIDS Care (Chic Ill). 2009;7(5):238-44.
Incidence and Determinants of Initiation into Cocaine Injection and Correlates of Frequent Cocaine Injectors
Researchers investigated the incidence and correlates of cocaine injection initiation and the impacts of daily cocaine injection among a cohort of injection drug users. Among 1603 participants, from May 1996 to December 2005, risk factors for initiation of cocaine injection among baseline heroin users were determined by Cox proportional hazards regression and correlates of daily cocaine injection by generalized estimating equations. Of the 238 individuals who had never injected cocaine, 200 (84%) had at least one follow-up visit and 121 (61%) consequently initiated into cocaine injection, yielding an incidence density of initiation into cocaine injection of 21.9% (95% confidence interval (CI): 17.9-25.8) per 100 person-years. In a multivariate model, Downtown Eastside (DTES) residence (adjusted hazard ratio (AHR)=2.46, 95% CI: 1.68-3.60), incarceration (AHR=1.50, 95% CI: 1.01-2.24), requiring help injecting (AHR=1.57, 95% CI: 0.99-2.49), and binge drug use (AHR=1.82, 95% CI: 1.22-2.73) remained associated with initiation into cocaine injection. DTES residence (adjusted odds ratio (AOR)=1.99, 95% CI: 1.62-2.46), unstable housing (AOR=1.28, 95% CI: 1.04-1.53), incarceration (AOR=1.29, 95% CI: 1.04-1.60), sex trade involvement (AOR=1.46, 95% CI: 1.15-1.85), requiring help injecting (AOR=2.11, 95% CI: 1.73-2.58)), borrowing syringes (AOR=1.81, 95% CI: 1.35-2.43) and binge drug use (AOR=2.16, 95% CI: 1.81-2.58) were independently associated with daily cocaine injection. These findings show that the baseline prevalence and subsequent incidence of initiation into cocaine injection was high in this population. Daily cocaine injection was independently associated with a number of health and social harms, including elevated HIV risk behavior. Lloyd-Smith E, Wood E, Li K, Montaner J, Kerr T. Incidence and determinants of initiation into cocaine injection and correlates of frequent cocaine injectors. Drug Alcohol Depend. 2009;99(1-3):176-82.
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 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 (N=297), Miami (N=186) and Sydney, Australia (N=156). 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. Scheier L, Ben Abdallah A, Inciardi J, Copeland J, Cottler L. Tri-city study of ecstasy use problems: a latent class analysis. Drug Alcohol Depend. 2008;98(3):249-63.
High Dead-Space Syringes and the Risk of HIV and HCV Infection among Injecting Drug Users
This study examines the association between using and sharing high dead-space syringes (HDSSs)-which retain over 1000 times more blood after rinsing than low dead-space syringes (LDSSs)-and prevalent HIV and hepatitis C virus (HCV) infections among injecting drug users (IDUs). A sample of 851 out-of-treatment IDUs was recruited in Raleigh-Durham, North Carolina, between 2003 and 2005. Participants were tested for HIV and HCV antibodies. Demographic, drug use, and injection practice data were collected via interviews. Data were analyzed using multiple logistic regression analysis. Participants had a mean age of 40 years and 74% are male, 63% are African American, 29% are non-Hispanic white, and 8% are of other race/ethnicity. Overall, 42% of participants had ever used an HDSS and 12% had shared one. HIV prevalence was 5% among IDUs who had never used an HDSS compared with 16% among IDUs who had shared one. The HIV model used a propensity score approach to adjust for differences between IDUs who had used an HDSS and those who had never used one. The HCV models included all potential confounders as covariates. A history of sharing HDSSs was associated with prevalent HIV (odds ratio=2.50; 95% confidence interval=1.01, 6.15). Use and sharing of HDSSs were also associated with increased odds of HCV infection. However, prospective studies are needed to determine the extent to which sharing HDSSs is associated with increased HIV and HCV incidence among IDUs. Zule W, Bobashev G. High Dead-Space Syringes and the risk of HIV and HCV infection among injecting drug users. Drug Alcohol Depend. 2009;100(3):204-13.
Incarceration and Drug Use Patterns among a Cohort of Injection Drug Users
Drug law enforcement remains the dominant response to drug-related harm. However, the impact of incarceration on deterring drug use remains under-evaluated. Researchers explored the relationship between incarceration and patterns of drug use among people who inject drugs (IDU). Using generalized estimating equations (GEE), they examined the prevalence and correlates of injection cessation among participants in the Vancouver Injection Drug User Study followed over 9 years. In subanalyses, they used McNemar's tests and linear growth curve analyses to assess changes in drug use patterns before and after a period of incarceration among participants reporting incarceration and those not incarcerated. Among 1603 IDU, 842 (53%) reported injection cessation for at least 6 months at some point during follow-up. In multivariate GEE analyses, recent incarceration was associated negatively with injection cessation [adjusted odds ratio (AOR) = 0.43, 95% confidence interval (CI) 0.37-0.50], whereas the use of methadone was associated positively with cessation (AOR = 1.38, 95% CI 1.22-1.56). In subanalyses assessing longitudinal patterns of drug use among incarcerated individuals and those not incarcerated over the study period, linear growth curve analyses indicated that there were no statistically significant differences in patterns of drug use between the two groups (all P > 0.05). These observational data suggest that incarceration does not reduce drug use among IDU, and in fact incarceration may inhibit access to mechanisms that promote injection cessation among IDU. By contrast, the results indicate that methadone use is associated positively with injection cessation, independent of previous frequency of drug use. DeBeck K, Kerr T, Li K, Milloy M, Montaner J, Wood E. Incarceration and drug use patterns among a cohort of injection drug users. Addiction. 2009;104(1):69-76.
Predictors and Comparisons of Polydrug and Non-polydrug Cocaine Use in Club Subcultures
Club drug users have been shown to tend towards patterns of polydrug use, which has been linked to adverse health outcomes, such as impaired mental health, overdose, dependence, infectious disease exposure, and decreased cognitive functioning. This study analyzed data from the Club Drugs and Health Project, a study designed to examine the patterns and contexts of club drug use among young adults. Four-hundred recent club drug users were recruited through time-space sampling. Among recent cocaine users (n = 361), 61.2% were polydrug users. Male gender was predictive of polydrug cocaine use (OR = 1.66). Gay, lesbian, and bisexual (GLB) sexual orientation, White race, and Non-Latino ethnicity were not. No differences in mental health factors were found between cocaine polydrug users and users of only cocaine. However, polydrug users were significantly more likely to score high on drug-related sensation seeking as well as to use drugs to deal with unpleasant emotions and to have pleasant times with others. In light of these findings, the authors stress that prevention and intervention efforts should consider contextual and motivational factors in attempting to reduce polydrug use and its negative effects. Kelly B, Parsons J. Predictors and comparisons of polydrug and non-polydrug cocaine use in club subcultures. Am J Drug Alcohol Abuse. 2008;34(6):774-81.
Pathways from Adolescent Marijuana Use in the Familial and Non-Familial Environments to Marijuana Use in the Fourth Decade of Life
This research examined the extent to which marijuana use by parents, siblings, peers, and others from adolescence (mean age 14) through early adulthood (mean age 27), predicts one's own marijuana use in the fourth decade of life (assessed at mean ages of 32 and 37). Understanding the longitudinal interpersonal influences on, and stability of, marijuana use is an important part of expanding efforts to prevent marijuana use by adolescents. 586 participants from a longitudinal sample interviewed since 1983 and who completed marijuana study measures in the two most recent study waves (2002, 2007) participated. Participants were predominantly White (92%) and female (57%). The research team analyzed the data using the LISREL VIII structural equation program. Maximum likelihood methods were used to estimate the models and the LISREL goodness of fit index (GFI) and the root mean square error of approximation (RMSEA) were used to assess the fit of the models. The research team obtained the following indices of fit: GFI=.99 and RMSEA=.03, indicating a satisfactory model of fit. Findings indicated the influence of earlier parental marijuana use on their offspring's later marijuana use as an adult was mediated through sibling marijuana use, which in turn was related to peer and significant other marijuana use. In addition, aspects of the familial environment (sibling marijuana use) and the non-familial environment (peer and significant other marijuana use) had direct effects on the participants' marijuana use in the fourth decade of life. Results emphasize the importance of the impact of the peer network in young adulthood on the individual''s marijuana use over time and support prevention efforts that target social networks of young adults as a locus through which long-lasting marijuana habits are formed. Brook JS, Zhang C, Koppel J, Brook DW. Pathways from earlier marijuana use in the familial and non-familial environments to self-marijuana use in the fourth decade of life. Am J Addict. 2008:497-503.
Poverty, Bridging between Injecting Drug Users and the General Population, and "Interiorization" may Explain the Spread of HIV in Southern Brazil
This analysis examined structural determinants and the role of injecting drug use as bridges to the general population affected the AIDS subepidemic in southern Brazil during 1986-2000. Data from 288 southernmost Brazilian municipalities were analyzed. Using hierarchical modeling and inputs from a Geographic Information System, a multilevel model was constructed. The dependent variable was the logged AIDS standardized incidence rate (among the heterosexual population aged 15-69-years-old); independent variables included indicators for education, water provision, sewage, and garbage collection, per capita income, Gini coefficient (on income), Human Development Index, indicators of accessibility, and AIDS rate among IDUs. Significant predictors included AIDS rate among IDUs, distance from/to highways/railways, the Human Development Index and the ratio of residents who have access to sanitary installations. Poverty (as measured by socioeconomic indicators) and bridging from IDUs were found to contribute to the spread of HIV/AIDS in Brazilian southern municipalities. Hacker M, Leite I, Friedman S, Carrijo R, Bastos F. Poverty, bridging between injecting drug users and the general population, and "interiorization" may explain the spread of HIV in southern Brazil. Health Place. 2009;15(2):514-9.