Pathways to hiv risk and vulnerability among lesbian, gay, bisexual, and transgendered methamphetamine users: a multi-cohort gender-based analysis

Marshall et al. BMC Public Health 2011, 11:20 Pathways to HIV risk and vulnerability amonglesbian, gay, bisexual, and transgenderedmethamphetamine users: a multi-cohortgender-based analysis Brandon DL Marshall1,2, Evan Wood1,3, Jean A Shoveller2, Thomas L Patterson4, Julio SG Montaner1,3,Thomas Kerr1,3* Background: Methamphetamine (MA) use continues to be a major public health concern in many urban settings.
We sought to assess potential relationships between MA use and individual, social, and structural HIV vulnerabilitiesamong sexual minority (lesbian, gay, bisexual or transgendered) drug users.
Methods: Beginning in 2005 and ending in 2008, 2109 drug users were enroled into one of three cohort studiesin Vancouver, Canada. We analysed longitudinal data from all self-identified sexual minority participants (n = 248).
Logistic regression using generalized estimating equations (GEE) was used to examine the independent correlatesof MA use over time. All analyses were stratified by biological sex at birth.
Results: At baseline, 104 (7.5%) males and 144 (20.4%) females reported sexual minority status, among whom 64(62.1%) and 58 (40.3%) reported MA use in the past six months, respectively. Compared to heterosexualparticipants, sexual minority males (odds ratio [OR] = 3.74, p < 0.001) and females (OR = 1.80, p = 0.003) weremore likely to report recent MA use. In multivariate analysis, MA use among sexual minority males was associatedwith younger age (adjusted odds ratio [AOR] = 0.93 per year older, p = 0.011), Aboriginal ancestry (AOR = 2.59, p= 0.019), injection drug use (AOR = 3.98, p < 0.001), having a legal order or area restriction (i.e., “no-go zone”)impact access to services or influence where drugs are used or purchased (AOR = 4.18, p = 0.008), unprotectedintercourse (AOR = 1.62, p = 0.048), and increased depressive symptoms (AOR = 1.67, p = 0.044). Among females,MA use was associated with injection drug use (AOR = 2.49, p = 0.002), Downtown South residency (i.e., an areaknown for drug use) (AOR = 1.60, p = 0.047), and unprotected intercourse with sex trade clients (AOR = 2.62,p = 0.027).
Conclusions: Methamphetamine use was more prevalent among sexual minority males and females and wasassociated with different sets of HIV risks and vulnerabilities. Our findings suggest that interventions addressingMA-related harms may need to be informed by more nuanced understandings of the intersection between druguse patterns, social and structural HIV vulnerabilities, and gender/sexual identities. In particular, MA-focusedprevention and treatment programs tailored to disenfranchised male and female sexual minority youth arerecommended.
* Correspondence: [email protected] Columbia Centre for Excellence in HIV/AIDS, St. Paul’s Hospital, 608-1081 Burrard Street, Vancouver, BC, V6Z 1Y6, CanadaFull list of author information is available at the end of the article 2011 Marshall et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (, which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.
Marshall et al. BMC Public Health 2011, 11:20 assessed the relationships between MA use and a range Like many other marginalised groups, lesbian, gay, of individual, social, and structural HIV-related vulner- bisexual, and transgendered (LGBT) populations experi- abilities with the aim of indentifying through which ence a range of health inequities and vulnerabilities pathways MA use may exacerbate exposure to HIV risk.
compared to the general population [1]. In addition tothe multiple health conditions that disproportionately affect LGBT populations, sexual minorities also experi- ence significant barriers to accessing appropriate care The At Risk Youth Study (ARYS), Vancouver Injection and prevention services [2,3]. Due in part to the histori- Drug Users Study (VIDUS) and AIDS Care Cohort to cal invisibility of LGBT persons and a reluctance among Evaluate Access to Survival Services (ACCESS) are open some communities to consider sexual minorities as a prospective cohorts of drug users in Vancouver, Canada.
“legitimate” marginalised group, this population con- These studies comprise a larger program of research tinues to be underrepresented in public health research focused on the study of the initiation and natural history of injection drug use, and are administered by one A number of studies have demonstrated a high preva- research centre (i.e., the British Columbia Centre for lence of substance use and dependence among sexual Excellence in HIV/AIDS). The risk environment frame- minority groups [5,6]. For example, methamphetamine work is utilized as the theoretical foundation from (MA) use has been well studied among gay, bisexual, which to examine how a variety of factors within social, and other men who have sex with men (MSM), particu- physical, and political space interact to (re)-produce larly in relation to increased sexual risk behaviour and HIV and drug-related harm [19]. Recruitment proce- HIV transmission [7-9]. Although much less research dures for the three studies are similar, with the primary has been conducted among sexual minority women, sev- modes of enrolment being self-referral, word of mouth, eral cross sectional studies have demonstrated that les- and street outreach. Participants of all studies must have bian and bisexual-identified females report significantly resided in the greater Vancouver region and provided higher rates of MA use [10,11]. MA use among women informed consent to be eligible. Each study also had who inject drugs (IDU) has also been associated with specific eligibility criteria that are detailed briefly here.
sexual- and injection-related HIV risk behaviour [12].
ARYS consists of drug-using street-involved youth; thus, These studies and other research imply important gen- eligibility criteria included being between the age of 14 der differences in the typologies of and adverse health and 26 and the use of illicit drugs other than or in addi- outcomes associated with MA use [13]; therefore, gen- tion to marijuana in the past 30 days. VIDUS is a study der-based analyses involving sexual minority populations of HIV-negative IDU in which all participants must are needed to better inform effective public health have injected an illicit drug in the past 6 months to be eligible for inclusion. ACCESS is a cohort of HIV-posi- Although the individual and psychosocial factors that tive individuals, who, similar to those in ARYS, must drive HIV risk within the context of MA use are rela- have recently used an illicit drug other than or in addi- tively well understood [14-16], research has only begun tion to marijuana. Detailed sampling and recruitment to elucidate how environmental and structural determi- procedures for these three cohorts have been described nants link MA use with increased HIV vulnerability elsewhere [20-22]. In this analysis, we combined data [17]. In order to most effectively reduce MA-related from all three studies to achieve a sample size with suf- exposure to HIV risks, several authors have called for ficient power to examine MA use among the sub-sample the investigation of personal, social, environmental, and of participants who identified as a sexual minority.
structural correlates of MA use and harms [17,18]. The While combining data from studies with different inclu- “risk environment” framework, which posits that factors sion criteria may present some challenges, we note that exogenous to the individual intersect to (re)-produce all studies rely on harmonized recruitment and data col- HIV risk and other drug-related harms [19], provides lection tools. Furthermore, combining the datasets per- one such conceptual model to guide investigation of the mitted an examination of MA use patterns across a associations between MA use and HIV vulnerabilities diverse spectrum of drug users (e.g., street-involved operating at various levels of influence.
Using data collected from three large ongoing pro- At baseline and semi-annually, participants completed spective cohort studies of drug users in Vancouver, a lengthy interviewer-administered questionnaire. Socio- Canada, we sought to determine the prevalence of MA demographic data, as well as information pertaining to use among sexual minority males and females. Further- drug use patterns, risk behaviours, and health care utili- more, relying on a risk environment approach, we sation are collected. The survey for each study consists Marshall et al. BMC Public Health 2011, 11:20 of a uniform set of questions, which permits the aggre- non-injection MA use in the past 6 months, respec- gation and analysis of data from all enrolled participants.
tively. All variables examined in this study, including Nurses collected blood specimens for HIV and hepatitis the outcomes and independent variables of interest, C serology and also provided basic medical care and were assessed consistently and equivalently across all referrals to appropriate health care services. Participants received $20 for each study visit. All studies have been Based on prior literature examining MA use among approved by the University of British Columbia/Provi- marginalised populations [12,26-29], we assessed as dence Health Care Research Ethics Board.
explanatory variables a broad set of sociodemographiccharacteristics, drug use variables, sexual activities, mar- kers of violence and depression, and contextual factors.
Data from each cohort used in this analysis was col- These variables were also chosen to represent both lected during the same time frame; thus, all individuals “micro”- (i.e., the immediate social environment of drug were observed over the same follow-up period. All parti- use) and “macro"- (i.e., the societal, economic, and legal cipants who completed a baseline survey between Sep- context that structure drug use and harm) levels articu- tember 2005 and May 2008 were eligible for inclusion.
lated by the risk environment framework [19]. Sociode- At baseline, participants were asked to identify their bio- mographic characteristics examined included age (per logical sex at birth and their current sexual orientation.
year older), Aboriginal ancestry (yes versus no), current “Sexual minority status” was defined as answering affir- relationship status (single/dating versus married/regular matively to one of: gay, lesbian, bisexual, transsexual, partner), and baseline HIV status (positive versus nega- transgendered, or other. Participants who refused to tive). All other variables (unless otherwise indicated) report their sex at birth or current sexual and gender referred to behaviours or activities in the past 6 months identity were excluded from this analysis.
since the date of the interview. Drug use variablesassessed included other stimulant use (i.e., non-injection cocaine use and crack use, respectively), any injection The primary hypothesis guiding this analysis was based drug use, experiencing a non-fatal overdose, and binge on the risk environment framework and a careful assess- drug use. As defined previously [30], the latter was oper- ment of prior literature investigating the relationship ationalised as the self-reported use of drugs more often between MA use and HIV risk behaviour. We hypothe- than usual. We also examined the following sexual sized that MA use among sexual minority drug users activities: number of casual or regular partners exclud- would be associated with differing exposure to indivi- ing those in the context of sex work (>1 versus ≤1); any dual, social, and structural HIV vulnerabilities. In an vaginal or anal unprotected intercourse with casual or effort to build on previous studies [16,23,24], we sought regular partners (yes versus no); and sex trade work, not only to examine individual-level HIV risk behaviour defined as a categorical variable with “no” as the refer- but also contextual factors including homelessness, ence level and consistent condom use with all clients neighbourhood of residence, the consumption of drugs and any unprotected intercourse with clients as the sec- in public, and the regulation of these spaces by law ond and third levels, respectively. We ascertained invol- enforcement personnel. We also considered the relation- vement in (i.e., committing) and exposure to (i.e., ship between MA use and physical violence and depres- experiencing) physical violence (yes versus no). We also sion, which have been identified as independent risk used the Center for Epidemiologic Studies Depression factors for HIV infection [9,25]. Finally, we hypothesized Scale (CES-D) with a cut-off of ≥16 to measure the level that the relationship between MA use and these factors of depressive symptomatology among participants [31].
would differ significantly between sexual minority males Finally, contextual factors examined included: residency in the Downtown South (DTS), an area known as amixed business and entertainment district that is also inhabited by a large street youth population [32]; home- The primary outcome of interest was ascertained by lessness (yes versus no); having a warrant or area examining responses to the questions, “In the last six restriction (i.e., “no go zone”) impact access to services months, did you use non-injection crystal methampheta- or influence where drugs are consumed or purchased mine?” and “In the last six months, did you inject crystal (yes versus no); and using drugs in public spaces (>75% methamphetamine?” Participants who responded “yes” of the time versus ≤75% of the time). Warrants and area to either or both questions were defined as crystal restrictions are legal orders to restrict access to certain methamphetamine (MA) users in all subsequent ana- areas of the city, and are commonly issued by law enfor- lyses. We also determined the proportion of partici- cement personnel in an attempt to disrupt crime and pants reporting daily or greater use of injection or Marshall et al. BMC Public Health 2011, 11:20 (n = 43, 2.1%), lesbian (n = 9, 0.4%), and transsexual, As a preliminary analysis, we compared the baseline transgendered, or other (n = 28, 1.3%). Among those sociodemographic characteristics and MA use patterns who reported their biological sex at birth as female, 144 between heterosexual and sexual minority participants, (20.4%) identified as a sexual minority compared to only stratified by biological sex at birth. The Pearson chi- square test was used to compare categorical variablesand the Wilcoxon rank sum test was used for continu- ous variables. We then identified the longitudinal corre- Sociodemographic characteristics and methamphetamine lates of MA use by using generalized estimating use patterns for males and females stratified by sexual equations (GEE) with a logit link for binary outcomes.
orientation are displayed in Table 1. At baseline, sexual GEE were appropriate for this analysis since the factors minority males were more likely to be younger (median associated with recent MA use over the baseline and = 33 versus 39, p = 0.001), HIV positive (40.4% versus four follow-up periods were serial (i.e., time-dependent) 21.2%, p < 0.001), and of Aboriginal ancestry (40.4% ver- variables. GEE account for the correlation between sus 23.7%, p < 0.001). In contrast, sexual minority repeated measures for each subject; thus, valid estimates females were less likely to be of Aboriginal ancestry of association and standard errors are obtained [34].
(33.3% versus 43.9%, p = 0.023). Among both males and Since GEE models incorporate periods during which females, sexual minority participants were significantly participants report engaging and not engaging in the more likely to report injection and non-injection MA outcome, data from all baseline and follow-up interviews use in the past 6 months (Table 1). Notably, over half (62.1%) of sexual minority males reported recently using Since a primary objective of this study was to deter- MA, and a significant proportion (16.7%) reported mine whether the correlates of MA use differed between injecting MA at least daily. Approximately half (n = 142, males and females, we stratified the analyses by biologi- 57.3%) of sexual minority participants reported having cal sex at birth and constructed two multivariate mod- used MA for at least a year since the date of the base- els. We applied a modified backward stepwise procedure to select covariates based on two criteria: the Akaikeinformation criterion (AIC) and type-III p-values [35].
Longitudinal Correlates of Methamphetamine Use Lower AIC values indicate a better overall fit and lower In Table 2, we report the results of the longitudinal ana- p-values indicate higher variable significance. Starting lysis examining the factors associated with MA use with a full model containing all variables that were sig- among sexual minority males. Bivariate analyses indi- nificant in bivariate analyses at p < 0.10, covariates were cated that male MA users were more likely to experi- removed sequentially in order of decreasing p-values. To ence a variety of sexual HIV risks and vulnerabilities, compensate for potential variations in recruitment and including for example multiple recent sex partners selection procedures between studies, we also adjusted (odds ratio [OR] = 1.91, p = 0.002), unprotected inter- each model for cohort of enrolment. At each step, the course (OR = 1.86, p = 0.004), and unprotected inter- p-values of each variable and the overall AIC were course in the context of sex work (OR = 3.25, p = recorded, with the final model having the lowest AIC.
0.005). MA using men were also more likely to report Statistical analysis was conducted using SAS version injection drug use (OR = 2.31, p = 0.004), experience 9.1.3 (SAS Institute Inc., Cary, North Carolina, USA) physical violence (OR = 1.76, p = 0.004), commit physi- cal violence (OR = 1.90, p = 0.025) and exhibit depres-sive symptoms (OR = 1.79, p = 0.010). In multivariate analysis, independent correlates of MA use among sex- ual minority males included: younger age (adjusted odds Between September 2005 and May 2008, 2109 unique ratio [AOR] = 0.93, p = 0.011), Aboriginal ancestry individuals were enrolled into the ARYS, VIDUS or (AOR = 2.59, p = 0.019), injection drug use (adjusted ACCESS cohorts. A total of 14 (0.7%) refused to report odds ratio [AOR] = 3.98, p < 0.001), unprotected sexual their sex at birth or current sexual/gender identity and intercourse (AOR = 1.62, p = 0.048), increased depres- were thus excluded for the analysis. Of the 2095 eligible sive symptoms (AOR = 1.67, p = 0.044), and having an participants, 1389 (66.3%) were male and 706 (33.7%) area restriction impact access to services or influence were female. Among all participants, the median age at where drugs are used or purchased (AOR = 4.18, p = baseline was 37.0 (IQR: 24.7 - 45.4) and 641 (30.6%) were of Aboriginal ancestry. The majority identified Increased sexual HIV vulnerabilities were also their sexual or gender identity as heterosexual (n = observed among MA-using sexual minority females 1847, 88.2%), followed by bisexual (n = 168, 8.0%), gay (Table 3). For example, females reporting recent MA Marshall et al. BMC Public Health 2011, 11:20 Table 1 Baseline sociodemographic characteristics and methamphetamine use patterns among ARYS, VIDUS, andACCESS participants, stratified by biological sex at birth and self-identified sexual orientation (n, % unless otherwiseindicated) Notes: * “sexual minority” refers to lesbian, gay, bisexual, transgendered, transsexual, or other orientation; † refers to activities in the past 6 months.
use were more likely to have multiple regular or casual In a multivariate analysis, several unique correlates of sex partners (OR = 1.55, p = 0.029). Several associations MA use emerged among sexual minority females. In that were observed among MA-using males were also contrast to males, MA-using females were more likely significant among females. For example, female MA to reside in the Downtown South neighbourhood (AOR users were younger (OR = 0.95, p = 0.005), more likely = 1.60, p = 0.047). Furthermore, MA use among sexual to inject drugs (OR = 1.68, p = 0.011), and reported ele- minority females was independently associated with vated rates of unprotected intercourse in the context of unprotected intercourse with sex trade clients (AOR = sex work (OR = 3.27, p = 0.001). In contrast, MA-using 2.62, p = 0.027). Similar to males, MA-using females females were less likely to be of Aboriginal ancestry (OR were more likely to report injection drug use (AOR = Marshall et al. BMC Public Health 2011, 11:20 Table 2 Longitudinal analysis of factors associated with crystal methamphetamine use† among sexual minority* males(n = 104) Relationship status (single/dating vs. married/partner) Non-injection cocaine use† (yes vs. no) Number of sex partners† (>1 vs. ≤1) Sex trade work† (ref = no sex trade work) Consistent condom use with clients† (yes vs. ref) Any unprotected sex with clients† (yes vs. ref) Experience physical violence† (yes vs. no) Clinical depression (CES-D‡ ≥16 vs. <16) Area restrictions influence drug use (yes vs. no) Use drugs in public† (>75% vs. ≤75% of the time) Notes: model adjusted for cohort of recruitment; * “sexual minority” refers to lesbian, gay, bisexual, transgendered, transsexual, or other orientation; † refers toactivities in the past 6 months; ‡ CES-D refers to the Center for Epidemiologic Studies Depression Scale.
to the fact that sexual minority males reported heavier In the current study, we observed a high prevalence of MA use patterns compared to females, and thus may be MA use among sexual minority males and females in more likely to experience individual (i.e., depressive comparison to heterosexual participants. We also found symptoms) and contextual (i.e., exposure to law enforce- that, consistent with the risk environment framework, ment) MA-related sequelae. Finally, Aboriginal ancestry MA use was associated with an array of individual, was positively associated with MA use among males but social, and contextual HIV-related risks and vulnerabil- inversely associated with MA use among females.
ities among sexual minority drug users.
Consistent with other studies [7,8,36], MA use was Although some correlates of MA use (e.g., younger linked with unprotected intercourse among sexual min- age and injection drug use) were significant for both ority men. Although we were unable to ascertain the sexes, several important differences were observed. For context in which instances of unprotected intercourse example, unprotected intercourse involving regular or occurred, we point to other research indicating that casual partners was more common among males who homeless sexual minority males frequently experience reported using methamphetamine, while unprotected sexual victimization and abuse from partners [37].
intercourse in the context of sex work was associated Although more research is required to fully elucidate with MA use among females. Furthermore, only MA- casual mechanisms, we hypothesize that the relationship using males were more likely to experience depressive between sexual risk and MA use observed among this symptoms and report having area restrictions (i.e., “no sample of street-involved sexual minority men is less a go” zones) impact access to services of influence where function of desire to enhance sex but is in fact a marker drugs are used or purchased. These findings may be due of increased vulnerability within sexual relationships.
Marshall et al. BMC Public Health 2011, 11:20 Table 3 Longitudinal analysis of factors associated with crystal methamphetamine use† among sexual minority*females (n = 144) Relationship (single/dating vs. married/partner) Non-injection cocaine use† (yes vs. no) Number of sex partners† (>1 vs. ≤1) Sex trade work† (ref = no sex trade work) Consistent condom use with clients† (yes vs. ref) Any unprotected sex with clients† (yes vs. ref) Experience physical violence† (yes vs. no) Clinical depression (CES-D‡ ≥16 vs. <16) Area restrictions influence drug use (yes vs. no) Use drugs in public† (>75% vs. ≤75% of the time) Notes: model adjusted for cohort of recruitment; * “sexual minority” refers to lesbian, gay, bisexual, transgendered, transsexual, or other orientation; † refers toactivities in the past 6 months; ‡ CES-D refers to the Center for Epidemiologic Studies Depression Scale.
A similar pathway may also explain the marginal asso- the production of HIV risk among sexual minority ciation between MA use and experiencing physical vio- women involved in survival sex work.
lence observed among males in this study.
The strongest correlate of MA use among sexual min- In multivariate analysis, among the subsample of ority men was reporting that a warrant or area restric- females engaging in sex work, MA use was associated tion impacted access to services or influenced where with unprotected intercourse with clients. This finding drugs are consumed or purchased. The socio-legal regu- can be situated within a growing literature demonstrat- lation of public space and its negative impact on the ing how social and structural inequities hinder the indi- health of homeless people and street-level drug users vidual agency of drug-using survival sex workers to has been described previously [41]. Recent work also practice HIV prevention and harm reduction with cli- suggests that the displacement of street-involved young ents [38]. In a recent study of female sex workers (FSW) people using warrants or area restrictions exacerbates in Vancouver, Canada, Shannon et al. [39] demonstrated stigma and increases sexual vulnerability and HIV risk that MA use is associated with living and working in [42]. Our findings suggest that having one’s movements marginalised public spaces (e.g., industrial areas). These restricted may also encourage transitions in drug use areas have been shown in previous research to be set- (including initiation of MA use), due perhaps to the tings of increased risk of violence and pressure from cli- forced removal of drug users from normative environ- ents to engage in unprotected sex [40]. Our results ments and social networks. It is also possible that MA support this work and indicate that MA use may aug- users are at an increased risk of incarceration and other ment the adverse impact of social-structural factors in interactions with the legal system, and are thus more Marshall et al. BMC Public Health 2011, 11:20 likely to be affected by punitive policies such as warrants true associations, particularly after adjustment for con- and area restrictions. This form of marginalisation (pro- founding. Furthermore, data from three studies with dif- duced by policies and practices meant to reduce expo- ferent inclusion criteria were combined and analysed, sure to street-level drug use and violence) is one which may have resulted in cohort or selection effects.
example of a population-level intervention that may To mitigate the potential impact of these biases, all sam- exacerbate inequity and worsen the health of vulnerable pling and data collection procedures were harmonized, and all multivariate models were adjusted for cohort of These findings also support the urgent need for recruitment. We note that all behaviours ascertained in increased resources and programming directed towards this study were self-reported, and we were unable to LGBT people who use methamphetamine. In order to confirm MA use with urine samples or other measures.
inform more effective interventions to reduce the harms We also recognize that our primary analysis was associated with MA, researchers must clearly articulate restricted to individuals who self-identified as a sexual how social/structural processes impact the health of sex- minority; therefore, heterosexual-identified individuals ual minorities. Once clearly identified, these factors can who engaged in same-sex activity were excluded. We then be the target of broad sets of evidence-based inter- chose not to rely on behavioural eligibility criteria (e.g., ventions to reduce health inequities and improve overall MSM), as we feel, as do others [50], that ignoring sexual health. For example, changes in government policy identity in HIV prevention efforts obscures the social along with community mobilization and solidarity pro- dimensions of sexuality that are critical for the develop- grams have been shown to be highly successful at redu- ment of effective and culturally relevant public health cing HIV risk among survival sex workers [44].
interventions. However, we note that public health Programs that support capacity-building in marginalised efforts should be made to provide appropriate services communities have also been shown to reduce health for non-LGBT identifying MSM/WSW, including pro- inequity and improve health outcomes [45]. Although grams that explicitly acknowledge and accept diverse further research is required to elucidate the potential sexual experiences and identities [51]. We were unable impact of specific enforcement practices (e.g., area to ascertain motivations for MA use, which if examined restrictions) on MA use and related harms, improved may have accounted some of the observed differences in coordination between policing and public health initia- the characteristics and consequences of MA use tives may represent another opportunity to prevent the between male and female participants in this study.
(un)-intended consequences of public policies meant to Finally, although our data are longitudinal, we do not reduce crime and street disorder [46]. Finally, additional wish to imply that this analysis provides thorough research is required to identify specific programmatic insight into the causal pathways linking MA use and needs of subpopulations within sexual minority commu- HIV risk with broader social and structural inequities.
nities, including for example transgendered youth.
To complement structural interventions, some beha- vioural approaches (e.g., cognitive behavioural therapy) We have demonstrated in a longitudinal data set a high offer promise [47]. For example, LGBT-specific sub- prevalence of MA use among a cohort of street-involved stance abuse treatment programs have been found to sexual minority drug users. To our knowledge, this is reduce engagement in high-risk sex among drug-using the first study to extend the risk environment approach gay men [48]. Harm reduction programs, particularly as a theoretical foundation from which to understand those offering tailored services for MA users, are effec- the contexts of risk associated with MA use among tive and well received by clients [49]. Finally, given the LGBT populations. Consistent with the risk environ- associations between Aboriginal ancestry, sexual orienta- ment framework, MA use was associated with distinct tion, and MA use observed in this study, methampheta- sets of individual, social, and structural HIV risks and mine-specific programming should carefully identify the vulnerabilities among women and men, respectively; manner in which cultural and sexual identities shape therefore, comprehensive interventions that involve sec- drug use and HIV risk within specific contexts and tors outside of health (e.g., housing, law enforcement), in addition to drug-specific approaches tailored to This study has a number of limitations that should be LGBT populations, are required to reduce HIV vulner- noted. The ARYS, VIDUS, and ACCESS cohorts are not ability and MA-related harms. Finally, researchers and random samples of the eligible population; thus, findings public health practitioners must identify multi-sector may not necessarily be generalizable to other urban population-level interventions that do not exacerbate areas in which MA use is prevalent. The small sample inequity but successfully mitigate health inequities sizes may have resulted in insufficient power to detect Marshall et al. BMC Public Health 2011, 11:20 Frosch D, Shoptaw S, Huber A, Rawson RA, Ling W: Sexual HIV risk among The authors thank the study participants for their contribution to the gay and bisexual male methamphetamine abusers. J Subst Abuse Treat research, as well as current and past investigators and staff. We would specifically like to thank Deborah Graham, Peter Vann, Caitlin Johnston, Koblin BA, Husnik MJ, Colfax G, Huang Y, Madison M, Mayer K, Barresi PJ, Steve Kain, and Calvin Lai for their research and administrative assistance.
Coates TJ, Chesney MA, Buchbinder S: Risk factors for HIV infection The ARYS study was supported by the US National Institutes of Health (NIH) among men who have sex with men. AIDS 2006, 20:731-739.
grant R01-DA028532 as well as the Canadian Institutes of Health Research Parsons JT, Kelly BC, Wells BE: Differences in club drug use between (CIHR) grant MOP-102742. The VIDUS study was supported by NIH (R01- heterosexual and lesbian/bisexual females. Addict Behav 2006, DA011591). The ACCESS study was supported by NIH (R01-DA021525) and CIHR (MOP-79297). All studies are supported by a CIHR team grant RAA- Lampinen TM, McGhee D, Martin I: Increased risk of “club” drug use 79918. TK is supported by the Michael Smith Foundation for Health Research among gay and bisexual high school students in British Columbia. J (MSFHR) and the CIHR. BDLM is supported by senior graduate trainee Lorvick J, Martinez A, Gee L, Kral AH: Sexual and injection risk amongwomen who inject methamphetamine in San Francisco. J Urban Health 1British Columbia Centre for Excellence in HIV/AIDS, St. Paul’s Hospital, 608- Dluzen DE, Liu B: Gender differences in methamphetamine use and 1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada. 2School of Population responses: A review. Gend Med 2008, 5:24-35.
and Public Health, University of British Columbia, 2206 East Mall, Vancouver, Semple SJ, Patterson TL, Grant I: Motivations associated with BC, V6T 1Z3, Canada. 3Department of Medicine, University of British methamphetamine use among HIV+ men who have sex with men. J Columbia, St. Paul’s Hospital, 608-1081 Burrard Street, Vancouver, BC, V6Z 1Y6, Canada. 4Department of Psychiatry, University of California, 9500 Gilman Halkitis PN, Shrem MT: Psychological differences between binge and Drive, La Jolla, California, 92093-0680, USA.
chronic methamphetamine using gay and bisexual men. Addict Behav2006, 31:549-552.
Garofalo R, Mustanski BS, McKirnan DJ, Herrick A, Donenberg GR: TK had full access to all of the data and takes responsibility for the integrity Methamphetamine and young men who have sex with men: of the results and the accuracy of the statistical analysis. BM, TK, and JS understanding patterns and correlates of use and the association with conceived the study concept and design, and BM was responsible for the HIV-related sexual risk. Arch Pediatr Adolesc Med 2007, 161:591-596.
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JM, and TK. The manuscript was edited and revised by BM, EW, JS, TP, JM, Semple SJ, Strathdee SA, Zians J, Patterson TL: Factors associated with sex and TK. All authors read and approved the final version of the manuscript.
in the context of methamphetamine use in different sexual venuesamong HIV-positive men who have sex with men. BMC Public Health Dr Montaner reported receiving educational grants from and serving as an Rhodes T: The ‘risk environment’: a framework for understanding and ad hoc advisor to or speaking at various events sponsored by Abbott reducing drug-related harm. Int J Drug Policy 2002, 13:85-94.
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declare that they have no competing interests.
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Shoptaw S, Reback CJ, Peck JA, Yang X, Rotheram-Fuller E, Larkins S,Veniegas RC, Freese TE, Hucks-Ortiz C: Behavioral treatment approaches Submit your next manuscript to BioMed Central
for methamphetamine dependence and HIV-related sexual risk and take full advantage of:
behaviors among urban gay and bisexual men. Drug Alcohol Depend2005, 78:125-134.
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Reback CJ, Larkins S, Shoptaw S: Changes in the meaning of sexual riskbehaviors among gay and bisexual male methamphetamine abusers • Thorough peer review
before and after drug treatment. AIDS Behav 2004, 8:87-98.
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Cns drugs 2011;

ª 2011 Adis Data Information BV. All rights reserved. Role of Cannabinoids in Multiple SclerosisJohn P. Zajicek1 and Vicentiu I. Apostu21 Clinical Neurology Research Group, Peninsula College of Medicine and Dentistry, Plymouth, UK2 Clinical Neurology Research Group, Peninsula Medical School, Plymouth, UKAbstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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