Club drug use and associated high-risk sexual behaviour in six provinces in China

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1 bs_bs_banner RESEARCH REPORT doi: /add Club drug use and associated high-risk sexual behaviour in six provinces in China Yan-Ping Bao 1, Zhi-Min Liu 1, Jian-Hua Li 2, Rui-Min Zhang 2, Wei Hao 3, Min Zhao 4, Jie Shi 1, Jennifer M. McGoogan 5 & Lin Lu 1 National Institute on Drug Dependence, Peking University, Beijing, China, 1 Yunnan Institute for Drug Abuse, Xi Hua Yuan, Kunming, Yunnan, China, 2 Mental Health Institute, The Second Xiangya Hospital, Central South University, Hunan, China, 3 Shanghai Mental Health Center, Shanghai JiaoTong University School of Medicine, Shanghai, China 4 and National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China 5 ABSTRACT Aim To investigate the characteristics of the different club drugs and associated high-risk sexual behaviours in China. Design Multicentre cross-sectional study. Setting Drug Detoxification and Rehabilitation Centres in six provinces, China. Participants A total of 1434 eligible club drug users were included. Measurements Participants were investigated by trained interviewers using a self-designed structured questionnaire to collect information on club drug use and associated behaviours. Findings Methamphetamine was the most commonly abused drug in participants (73.92%), who used it in their or their friends homes by non-injection for the purpose of feeling euphoria. Among participants with sexual behaviours after club drug use, 75.21% reported having engaged in sex with multiple partners after club drug use during the past year and 79.84% had unprotected sex after using club drug during the past year. A two-level logistic model showed that male gender [adjusted odds ratio (AOR) = 7.14; 95% confidence interval (CI) = ], unmarried (AOR = 1.71, 95% CI = ), long duration of club drug use during their lifetime (AOR = 1.76, 95% CI = ) and severe acute intoxication after using club drugs during the past year (AOR = 2.11, 95% CI = ) were independent risk factors of multiple sex partners during the past year. Another two-level model showed that the club drug users who were female (AOR = 1.79, 95% CI = ) and had polydrug use during their lifetime (AOR = 1.55, 95% CI = ) had more risk for unprotected sex during the past year than without these characteristics. Conclusion High-risk sexual behaviours are common among club drug users in China. The prevention and intervention of club drug use could decrease the risk of sexual behaviours which further prevent HIV transmission and other sexually transmitted infections in China. Keywords China, club drug use, methamphetamine, risk factor, sexual behaviour, unprotected sex, sexually transmitted infections. Correspondence to: Yan-Ping Bao or Zhi-Min Liu, National Institute on Drug Dependence, Peking University, 38, XueYuan Road, Hai Dian District, Beijing , China. baoypstat@163.com or zhiminliu@bjmu.edu.cn Submitted 14 Sept 2012; initial review completed 19 Nov 2012; final version accepted 15 March 2013 INTRODUCTION The re-emergence of drug use in the late 1980s in China, particularly heroin injecting drug use, is known to be the initiator and early driver of China s HIV/AIDS epidemic. However, as the closely intertwined drug use and HIV/ AIDS epidemics have evolved and matured over time in China, they now have very different qualities. For example, as of 2007, the main driver of the HIV epidemic in China was no longer injection drug use, but rather sexual contact. Moreover, as of the end of 2011, an estimated 63.9% of new HIV infections were ascribed to sexual transmission events, while only 28.4% were accounted for by injection drug use [1]. Similarly, the main drivers of the drug use epidemic in China have also changed, as there is a broader spectrum of illicit drugs of abuse available to users. In particular, ketamine and an array of synthetic amphetamine-type stimulant (ATS) drugs including methamphetamine (MA), 3,4-methylenedioxy-Nmethylamphetamine (MDMA, also known as ecstasy ) and so-called Magu pills (which are typically capsules containing a mixture of MA and other drugs such as caffeine), have emerged recently in China and have

2 12 Yan-Ping Bao et al. quickly become popular. Originally, these synthetic drugs were abused among club-goers, hence the collective name club drugs. According to data from the China National Narcotic Control Commission (NNCC), approximately people (6.7% of all registered drug users in China) began to use or abuse MA, MDMA, ketamine or Magu pills in By the end of 2011, however, this number had swelled to an estimated 0.59 million people (32.7% of the 1.79 million registered drug users) [2]. Depending on their form, club drugs are taken by injection, snorting, smoking or swallowing. They act very quickly on the nervous system to accelerate neural transmission and give users feelings of confidence, energy and euphoria. Club drugs are also known for their strong influence on sexual behaviour, as they tend to enhance sexual desire, prolong sexual pleasure, lengthen sexual episodes, suppress inhibitions and generally increase high-risk sexual behaviours associated with HIV transmission, including having multiple partners, inconsistently using condoms, engaging in sexual marathons and/or in homosexual sex [3 6]. During the past decade, the vast majority of epidemiological research efforts and public health interventions related to drug use and HIV co-epidemics in China have been focused upon the high-risk behaviour of heroininjecting drug users. However, there is accumulating evidence from other countries that club drugs are increasingly important drivers of a broad range of sexually transmitted infections (STIs), including HIV, as a result of their influence on high-risk sexual behaviour [3,4,7 9]. Moreover, the use of club drugs may be particularly important for HIV transmission, as a few studies have suggested an association between club drug use and reduced antiretroviral treatment (ART) adherence among HIV-infected individuals as well as potential direct interactions between club drugs and ART medicines themselves [9]. While ART has been shown to reduce sexual transmission of HIV by 96% in a recent clinical trial [10], failure to adhere to ART regimens can result in seroconversions by sexual transmission, probably as a result of inadequate suppression of HIV viral load in plasma, semen and cervicovaginal fluids [10,11]. In terms of the direct effects of club drugs, one study actually suggests that amphetamine use can result in transmitted drug resistance rendering some ART medicines ineffective in these individuals [12], and yet another study indicates that amphetamines can directly stimulate HIV viral replication [13]. The combination of exaggerated high-risk sexual behaviour among club drug users and the potentially higher transmission efficiency of HIVinfected club drug users highlights the urgent need for a better understanding of this problem, so that effective interventions can be implemented quickly. Although a few studies of the relationship between club drug use and high-risk sexual behaviours associated with HIV transmission have been conducted in Thailand [14,15], and more recently in Cambodia [16,17], there is generally a dearth of data on this issue from developing Asian countries, many of which have very serious drug use and HIV epidemics. To the authors knowledge at the time this paper was submitted, only few reports on club drug use and HIV risk from China currently exist in the literature [18 20]. Our previous survey about HIV and human hepatitis C virus (HCV) prevalence among ATS use in six provinces in China indicated that ATS use may be a new driver of the HIV epidemic in China [20]. Therefore, it is in this context that we conducted the data analysis of club drug use and associated high-risk sexual behaviour in six different study sites across mainland China. The primary aim of our study was to investigate the use of the various club drugs and examine their associations with various drug use-related behaviours, including multiple sex partners and unprotected sex. METHODS Study design and participants A multicentre cross-sectional study of club drug use and associated behaviours was conducted at the Drug Detoxification and Rehabilitation Centers in Beijing and Shanghai municipalities and in Guangdong, Hunan, Hubei and Yunnan provinces from September 2009 to December The eligibility criteria included: (i) being at least 18 years of age, (ii) having a positive urine test for at least one club drug (MA, MDMA, ketamine or Magu pills) at the time of detoxification centre entry, (iii) meeting the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, Arlington, VA, USA) criteria for ATS or ketamine abuse or dependence and (iv) signed informed consent. The participants were excluded if they had serious physical illnesses such as an acute stage of cardiovascular disease, cerebrovascular disease or neurodegenerative diseases. Among 1496 enrolled drug users, 40 were excluded because their mainly abused drug was not one of MA, MDMA, ketamine or Magu pills; 22 drug users were excluded because fewer were aged less than 18 years (three) and missing values regarding sex (19). Finally, 1434 subjects (95.86%) were included in this analysis. Face-to-face interviews with each participant were conducted individually in a private room by trained interviewers using a self-designed structured questionnaire which was developed for the purposes of this study, in order to collect data on demographic characteristics, drug use history, drug use behaviours, drug use-related sexual behaviours and knowledge and attitudes about club drugs and HIV/AIDS.

3 Club drug use and sexual risk behaviour in China 13 Statistical analysis All data were double-entered, and the consistency of both databases was compared using Epi data software (Epi Data Association, Odense, Denmark). The characteristics of drug users and history of drug use among male and female subjects were described. Not everyone had engaged in sexual behaviour after using club drugs; 718 subjects who answered the question about the number of sex partners ever engaged with after using club drugs in the past year were included in the analysis of exploring the associated factor of multiple sex partners, and 754 subjects who answered the question of condom use after club drug use in the past year were included in the analysis of exploring the risk factor of unprotected sex. After missing values were excluded, the two-level logistic regression model was used to explore the associated factors using the PROC GLIMMIX procedure in SAS. The study sites were specified at level 2, and as a random-effect parameter, subjects individual characteristics were specified at level 1 to obtain adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) for all possible associated variables. All statistical analyses were performed using SAS software version 9.2 (SAS Institute, Cary, NC, USA). All CIs reported are 95%, all P-values are two-sided, and P < 0.05 was considered to be statistically significant. Ethical approval The Institutional Review Board of Peking University Health Center reviewed and approved the research protocol and study questionnaire. Signed informed consent was obtained from all participants. RESULTS Demographic characteristics A total of 1434 eligible study participants were included in this analysis; participants were typical of club drug users in China, with a predominance of male, single, lower education level, unemployed, young people. The mean age of the participants was years, and 884 participants (61.65%) were young people aged less than 35 years. The majority (95.34%) belonged to the Han ethnic group, 935 (65.20%) were male, 917 (64.68%) completed primary school or junior high school, 803 (57.15%) were unemployed and 693 (48.87%) were unmarried. The characteristics among male and female drug users were summarized in Table 1. The mean age of female participants was years [standard deviation (SD) ± 8.14 years], which was significantly younger than male participants (34.30 ± 8.66). Compared with male participants, female drug users had a lower education level (23.08% senior high school or more versus 28.68%), were more likely to be unemployed (70.06 versus 48.63%) and unmarried (54.77 versus 45.73%); the difference was statistically significant (P < 0.05). History of club drug use As summarized in Table 1, MA was the most commonly ever used drug during the lifetime; 77.20% participants ever used MA, with 74.87% males and 81.56% females; 75.66% of participants reported that they had used it during the past month, 73.92% reported the use of mainly MA during their lifetime. Males were more likely to have a longer duration of club drug use in their lifetime (56.10% for 12 months or more versus 38.43%), a large proportion of polydrug use during their lifetime (44.71 versus 37.88%) and severe acute intoxication after club drug use in the past year (17.83 versus 10.62%) than females. Table 2 summarizes the characteristics of drug use behaviour according to the club drug used within the past month. While the primary place of drug use was home for 35.21% of MA users (34.80% male and 35.91% female), there were 28.48% subjects (30.85% male and 24.44% female) who used MA in dance halls or discos, the main sites of drug use for MDMA, ketamine and Magu pill users. Moreover, 73.81% MDMA users (76.36% male and 68.97% female), 76.81% ketamine users (79.78% male and 71.43% female) and 58.65% of Magu pill users (61.25% male and 44.23% female) used drugs in dance halls or discos. Pursuit of euphoria was identified as the main purpose for 45.53% MA users (48.25% male and 40.90% female), 52.38% MDMA users (56.36% male and 44.83% female), 51.81% ketamine users (51.69% male and 52.04% female) and 46.33% Magu pill users (47.75% male and 38.46% female) used drugs for the pursuit of euphoria. Magu pills were used for increasing energy (41.35%) and improving mood (42.52%) far more than other drugs, and more male MA, ketamine and Magu pill users used them for increasing energy than female users. Smoking was the main method of administration for MA users and Magu pill users, while the oral route was the administration method most commonly used by MDMA users and snorting was most common for ketamine users. Approximately 1% or fewer of these club drug users reported injecting drugs. In terms of frequency of drug use, 59.24% MA users (53.88% male and 68.85% female), 69.44% MDMA users (73.91% male and 61.54% female) and 46.03% ketamine users (38.92% male and 60.0% female) reported using these drugs fewer than five times per month. However, 58.70% Magu pill users (61.09% male and 44.68% female) used drugs between five and 19 times per month.

4 14 Yan-Ping Bao et al. Table 1 Demographic and history of club drug use characteristics of study participants. Characteristics Male Female Subjects n = 935 (%) n = 499 (%) n = 1434 (%) Study site # Beijing 93 (9.95) 49 (9.82) 142 (9.90) Shanghai 219 (23.42) 117 (23.45) 336 (23.43) Guangdong 112 (11.98) 160 (32.06) 272 (18.97) Hunan 103 (11.02) 23 (4.61) 126 (8.79) Hubei 226 (24.17) 34 (6.81) 260 (18.13) Yunnan 182 (19.47) 116 (23.25) 298 (20.78) Demographic characteristics Age (years) # (18.07) 187 (37.47) 356 (24.83) (37.75) 175 (35.07) 528 (36.82) (32.94) 115 (23.05) 423 (29.50) (11.23) 22 (4.41) 127 (8.85) Mean ± SD # ± ± ± 8.74 Ethnicity** Han 888 (95.69) 463 (94.68) 1351 (95.34) Minorities 40 (4.31) 26 (5.32) 66 (4.66) Education** # Illiterate or primary school 135 (14.61) 49 (9.92) 184 (12.99) Junior high school 460 (49.78) 273 (55.26) 733 (51.69) Secondary technical school 64 (6.93) 58 (11.74) 122 (8.60) Senior high school or more 265 (28.68) 114 (23.08) 379 (30.08) Employment** # Unemployed 445 (48.63) 358 (70.06) 803 (57.15) Employed 470 (51.37) 132 (26.94) 602 (42.85) Marital status** # Unmarried 423 (45.73) 270 (54.77) 693 (48.87) Married or cohabitating with a partner 369 (39.89) 142 (28.80) 511 (36.04) Divorced, separated, or widowed 133 (14.38) 81 (16.43) 214 (15.09) Club drug use characteristics Club drugs ever used during their lifetime* Methamphetamine 700 (74.87) 407 (81.56) 1107 (77.20) MDMA (ecstasy) 174 (18.61) 103 (20.64) 277 (19.32) Ketamine 329 (35.19) 173 (34.67) 502 (35.01) Magu pills 361 (38.61) 97 (19.44) 458 (31.94) Club drugs mainly used during their lifetime* Methamphetamine 668 (71.44) 392 (78.56) 1060 (73.92) MDMA (ecstasy) 25 (2.67) 19 (3.81) 44 (3.07) Magu pills 273 (29.20) 54 (10.82) 327 (22.80) Ketamine 148 (15.83) 91 (18.24) 239 (16.67) Club drugs used during the past month* Methamphetamine 684 (73.16) 401 (80.36) 1085 (75.66) MDMA (ecstasy) 55 (5.88) 29 (5.81) 84 (5.86) Ketamine 178 (19.04) 98 (19.64) 276 (19.25) Magu pills 289 (30.91) 52 (10.42) 341 (23.78) Polydrug use during their lifetime # No 517 (55.29) 310 (62.12) 827 (57.67) Yes 418 (44.71) 189 (37.88) 607 (42.33) Other substances ever used during their lifetime* Alcohol 279 (38.11) 129 (32.25) 408 (36.04) Heroin 196 (26.74) 122 (30.50) 318 (28.07) Duration of club drugs use (months) during their lifetime** # (43.89) 298 (61.57) 697 (50.04) (46.75) 164 (33.88) 589 (42.28) (9.35) 22 (4.55) 107 (7.68) Severe acute intoxication after club drug use during the past year** # Yes 161 (17.83) 41 (10.62) 202 (15.67) No 742 (82.17) 345 (89.38) 1087 (84.33) *Poly response; # P < 0.05; **With missing value. MDMA = 3,4-methylenedioxy-N-methylamphetamine; SD = standard deviation.

5 Club drug use and sexual risk behaviour in China 15 Table 2 Profiles of the club drugs used during past month by study participants. Methamphetamine (%) MDMA (ecstasy) (%) Ketamine (%) Magu pills (%) Characteristics Male Female Total Male Female Total Male Female Total Male Female Total n = 684 n = 401 n = 1085 n = 55 n = 29 n = 84 n = 178 n = 98 n = 276 n = 289 n = 52 n = 341 Place of drug use* Own home Friend s home Hotel Dance hall or disco Others Purpose of drug use* Pursuit of euphoria Increase energy Improve mood Ease socializing Avoid discomfort Others Administration of drug use* Smoking Oral Injecting Snorting Others Frequency of drug use (times/month)** *Poly response; **with missing value. MDMA = 3,4-methylenedioxy-N-methylamphetamine.

6 16 Yan-Ping Bao et al. Table 3 Sexual experiences and behaviour after club drug use among study participants. Characteristics Male / n(%) Female / n(%) Total / n(%) Sexual behaviour after club drug use ever in their lifetime* Yes 597 (63.92) 155 (31.25) 752 (52.59) No 337 (36.08) 341 (68.75) 678 (47.41) Relative frequency of sex after club drug use compared with time without drug use Increase 269 (52.13) 69 (52.67) 53 (8.19) No change 200 (38.76) 56 (42.75) 256 (39.57) Decrease 47 (9.11) 6 (4.53) 338 (52.24) Relative duration sexual episodes after club drug use compared with time without drug use* Increase 469 (78.30) 122 (74.85) 591 (77.56) No change 39 (6.51) 5 (3.07) 44 (5.77) Decrease 91 (15.19) 36 (22.09) 127 (16.67) Number of sexual partners ever engaged in sex after club drug use during the last year* 1 92 (16.34) 86 (55.48) 178 (24.79) (83.66) 69 (44.52) 540 (75.21) Condom use after club drug use during the last year* Use each time 130 (21.92) 22 (13.66) 152 (20.16) Occasionally use 347 (58.52) 116 (72.05) 463 (61.40) Never use 116 (19.56) 23 (14.29) 139 (18.44) *P < Associated sexual experiences and behaviours About half (52.59%) of drug users reported having sex after using club drugs; however, the proportion in females (31.25%) was significantly lower than that in male subjects (63.92%) (Table 3). Among the participants who reported having sex after using club drugs, 75.21% had engaged in sex with two or more different partners during the past year, and 79.84% had unprotected sex during the past year. Further analysis showed that 44.52% female subjects reported multiple sex partners during the past year, which is lower than that in male (83.66%). However, female drug users had more risk for unprotected sex; the percentage of never or occasional condom use after using club drugs among female drug users was 86.34%, which was significantly higher than that in male subjects (78.08%). Correlates of multiple sex partners and unprotected sex Among the 718 participants who reported the number of sex partners engaged with after using club drugs during the past year, the participants were categorized as positive for multiple sex partners if they reported ever engaging in sex with multiple partners during the past year. The twolevel logistic regression model was used to explore the associated factors. Among the 754 participants who answered the question of condom use after club drug use during the past year, participants were categorized as positive for unprotected sex if they reported never or occasional condom use during the past year. The data were further examined by the two-level logistic regression model to explore the risk factors of unprotected sex. The variables and code included in the two-level logistic model are listed in the Supporting information, Table S1; study sites were specified at level 2 as a random effect in the model and individual variables were specified at level 1 in the PROC GLIMMIX procedure in SAS version 9.2. As summarized in Table 4, the two-level logistic model showed that being male [adjusted odds ratio (AOR) = 7.14; 95% (CI) = ), unmarried (AOR = 1.71; 95% CI = ), with a long history of club drug use during their lifetime (AOR = 1.76, 95% CI = ) and history of severe acute intoxication after using club drugs during the past year (AOR = 2.11, 95% CI = ) were associated independently with multiple sex partners after using drugs during the past year. Another two-level model showed that female club drug users (AOR = 1.79, 95% CI ) and polydrug users during their lifetime (AOR = 1.55, 95% CI = ) had a greater risk for unprotected sex during the past year than the drug users without these characteristics. DISCUSSION This was a nationwide systematic multicentre survey of the characteristics of drug use behaviours in club drug users and associated high-risk sexual behaviour in China.

7 Club drug use and sexual risk behaviour in China 17 Table 4 Two-level logistic model for risk factors of multiple sex partners and unprotected sex after using club drugs among club drug users who endorsed these behaviours. Reporting multiple sex partners (n = 540) Reporting unprotected sex (n = 602) Characteristics Adjusted OR 95% CI Adjusted OR 95% CI Age group Gender (female versus male) * * Ethnicity (minority versus Han) Education Employment (unemployed versus employed) Marital status Unmarried versus married * Divorced or widowed versus married Polydrug use during their lifetime (yes versus no) * Duration of club drug use during their lifetime (months) * Severe acute intoxication after club drug use during the past year (yes versus no) * *P < OR = odds ratio; CI = confidence interval. The survey showed that MA was the most primarily used drug among the participants; the main locations of drug use were the home for MA and dance halls or discos for MDMA, ketamine and Magu pills. The pursuit of euphoria was the main reason for drug use. The majority of the participants used drugs by a non-injection route of administration. Sexual risk behaviours were common among club drug users. The factors of polydrug use during the past year, long history of club drug use in their lifetime and severe acute intoxication after drug use during the past year were associated with sexual risk behaviours among this population. The survey showed the typical characteristics of club drug users in China, with a predominance of single unemployed and young people, and the significant gender differences of characteristics and drug use history among club drug users. The findings indicated that unemployed, unmarried, low education-level and younger females were a newly appearing high-risk population of club drug use. However, male subjects were more likely to have severe drug use history, including polydrug use, during their lifetime, longer duration and severe acute intoxication during the past year after drug use, which was associated with high-dose drug use. This finding further indicated that comprehensive intervention should be given to the possible high-risk population with single, unemployed, low education-level and young people to prevent club drug use. Consistent with earlier epidemiology studies from Asia, MA was the primary drug used among club drugs users in China. The pursuit of euphoria was the main reason for drug use, which differed from the purpose of increasing energy for work in other countries in Southeast Asia [21]. The majority of the participants used drugs by a non-injection administration route, which was similar to the previous study [22]. The finding that high-risk sexual behaviours are common among club drug users was supported by a nationwide study [7,14]. The sexual stimulation effect of club drugs has been supported by animal studies [5,23]. Further evidence suggested that the drug-induced enhancement of sexual desire may be a contributory factor in HIV transmission [5]. One study from this survey showed that the HIV and HCV prevalence was 4.5 and 43.5%, respectively, among ATS users, indicating that the use of club drugs may have contributed to the rapid increase in the sexual transmission of HIV in China [20]. These findings have been supported by other studies which showed that the increased vulnerability to HIV spread and transmission is associated with a high prevalence of having multiple sex partners and unprotected sex after club drug use [15,16]. The present findings suggest that multiple sex partners after using club drug use was associated with male gender, being unmarried, a long duration of club drug use during the lifetime and severe acute toxic syndrome during the past year, and unprotected sex was associated with female polydrug use during the lifetime. The finding that males had more sex partners was similar to the results from a Thailand study, which showed that men reported a greater number of sex partners than women [15]. However, this study showed that females had a greater risk of unprotected sex and was not consistent with the Thailand study, which showed that condom use at last sex in males was infrequent, and further study is needed to verify this result. Our findings found that club

8 18 Yan-Ping Bao et al. drug users with a history of polydrug use during their lifetime had a greater risk of unprotected sex during the past year. Many epidemiological studies obtained a similar result; a study showed that heavy polydrug users had significantly more HIV-negative and unknownserostatus sex partners and more unprotected sex with these partners [24]. The club drug users with a long duration of drug use had a greater risk of exposure to multiple sex partners. These findings provide important information for developing sexual risk reduction interventions for club drug users. Although the risk of HIV infection and spread was high in club drug users [20], the knowledge and attitudes about club drugs and HIV transmission were not good. The Chinese government has made efforts to popularize intervention programmes for opiate drug users, especially injection drug users [25,26], and prevention programmes to reduce the sexual transmission of HIV have been scaled up in China [27]. However, prevention and intervention of HIV/AIDS concerning the high-risk behaviour of club drug users have not received enough attention. Another ongoing study showed that the majority (approximately 80%) of club drug users do not participate in intervention programmes including peer education or condom distribution. Appropriate responses and sexual risk reduction interventions are needed urgently for this population to prevent club drug use and the spread of HIV in China. The present study has several limitations. First, our sample population was recruited from detoxification centres and therefore should not be considered representative of club drug users. Secondly, the cross-sectional nature of this study prevented the determination of causal associations between the variables of interest. Thirdly, the self-reported nature of sexual behaviour data results in some bias due to the sensitivity of this topic in Chinese culture; moreover, the questionnaire was selfmade and developed for the purpose of this study; there were no reliability and validity data regarding the instrument. Therefore, the sexual risk data may be underestimated due to the instrument and social desirability bias. Fourthly, the limited geographic coverage of our study may not reflect accurately sexual risk behaviours and associated risk factors. Researchers planning future studies should consider collecting longitudinal data to investigate behaviours associated with HIV infection among this population. Despite these limitations, the findings of the present study provide valuable information regarding the use of the various club drugs and risk factors associated with multiple sex partners and unprotected sex after club drug use. The findings indicate that health education, employment training and assistance for the young, low-educated and unemployed high-risk population would perhaps be helpful in preventing club drug use. It is necessary to develop and implement comprehensive intervention strategies such as health education and condom distribution, etc. for club drug users to decrease the risk of sexual behaviours which further prevent HIV and other STI transmission in China. Declaration of interests None. Acknowledgements This work was supported by the Twelfth Five-Year Program of the Chinese Ministry of Science and Technology (grant no. 2008ZX and 2012ZX ), the National Basic Research Program of China (grant no. 2009CB522007), and the National Natural Science Foundation of China (grant no ). The funding organizations had no role in the development of study design or collection, analysis and interpretation of data. The authors wish to thank all the interviewers and participants for their cooperation. References 1. Ministry of Health of the People s Republic of China. Estimates for the HIV/AIDS Epidemic in China, Beijing, China: Joint United Nations Program on HIV/AIDS and World Health Organization; Archived at pdf on January 30, National Narcotics Control Commission. Annual Report on Drug Control in China (2012). Beijing, China: The Ministry of Public Security of People s Republic of China; Corsi K. F., Booth R. E. HIV sex risk behaviors among heterosexual methamphetamine users: literature review from 2000 to present. Curr Drug Abuse Rev 2008; 1: Urbina A., Jones K. Crystal methamphetamine, its analogues, and HIV infection: medical and psychiatric aspects of a new epidemic. Clin Infect Dis 2004; 38: Volkow N. D., Wang G. J., Fowler J. S., Telang F., Jayne M., Wong C. Stimulant-induced enhanced sexual desire as a potential contributing factor in HIV transmission. Am J Psychiatry 2007; 164: Semple S. J., Patterson T. L., Grant I. The context of sexual risk behavior among heterosexual methamphetamine users. Addict Behav 2004; 29: Degenhardt L., Mathers B., Guarinieri M., Panda S., Phillips B., Strathdee S. A. et al. Meth/amphetamine use and associated HIV: implications for global policy and public health. Int J Drug Policy 2010; 21: Drumright L. N., Patterson T. L., Strathdee S. A. Club drugs as causal risk factors for HIV acquisition among men who have sex with men: a review. Subst Use Misuse 2006; 41: Colfax G., Guzman R. Club drugs and HIV infection: a review. Clin Infect Dis 2006; 42: Cohen M. S., Chen Y. Q., McCauley M., Gamble T., Hosseinipour M. C., Kumarasamy N. et al. Prevention of HIV-1 infection with early antiretroviral therapy. N Engl J Med 2011; 365:

9 Club drug use and sexual risk behaviour in China Montaner J., Hogg R. Implications of the Henan Province report on the treatment as prevention debate. J Acquir Immune Defic Syndr 2011; 56: e101; author reply e Cachay E. R., Moini N., Kosakovsky Pond S. L., Pesano R., Lie Y. S., Aiem H. et al. Active methamphetamine use is associated with transmitted drug resistance to non-nucleoside reverse transcriptase inhibitors in individuals with HIV infection of unknown duration. Open AIDS J 2007; 1: Toussi S. S., Joseph A., Zheng J. H., Dutta M., Santambrogio L., Goldstein H. Short communication: methamphetamine treatment increases in vitro and in vivo HIV replication. AIDS Res Hum Retroviruses 2009; 25: Sutcliffe C. G., Aramrattana A., Sherman S. G., Sirirojn B., German D., Wongworapat K. et al. Incidence of HIV and sexually transmitted infections and risk factors for acquisition among young methamphetamine users in northern Thailand. Sex Transm Dis 2009; 36: Celentano D. D., Sirirojn B., Sutcliffe C. G., Quan V. M., Thomson N., Keawvichit R. et al. Sexually transmitted infections and sexual and substance use correlates among young adults in Chiang Mai, Thailand. Sex Transm Dis 2008; 35: Couture M. C., Sansothy N., Sapphon V., Phal S., Sichan K., Stein E. et al. Young women engaged in sex work in Phnom Penh, Cambodia, have high incidence of HIV and sexually transmitted infections, and amphetamine-type stimulant use: new challenges to HIV prevention and risk. Sex Transm Dis 2011; 38: Maher L., Phlong P., Mooney-Somers J., Keo S., Stein E., Couture M. C. et al. Amphetamine-type stimulant use and HIV/STI risk behaviour among young female sex workers in Phnom Penh, Cambodia. Int J Drug Policy 2011; 22: Jia Z., Wang W., Dye C., Bao Y., Liu Z., Lu L. Exploratory analysis of the association between new-type drug use and sexual transmission of HIV in China. Am J Drug Alcohol Abuse 2010; 36: Yang X., Xia G. Causes and consequences of increasing club drug use in China: a descriptive assessment. Subst Use Misuse 2010; 45: Bao Y. P., Liu Z. M., Lian Z., Li J. H., Zhang R. M., Zhang C. B. et al. Prevalence and correlates of HIV and HCV infection among amphetamine-type stimulant users in six provinces in China. J Acquir Immune Defic Syndr 2012; 60: McKetin R., Kozel N., Douglas J., Ali R., Vicknasingam B., Lund J. et al. The rise of methamphetamine in Southeast and East Asia. Drug Alcohol Rev 2008; 27: Wang Y. F., Zhang Y. Z., Lian Z., Sun G., Bao Y. P., Liu Z. M. Epidemiological characteristics of three new drugs abuse in Beijing. Chin J Drug Depend 2008; 17: Frohmader K. S., Lehman M. N., Laviolette S. R., Coolen L. M. Concurrent exposure to methamphetamine and sexual behavior enhances subsequent drug reward and causes compulsive sexual behavior in male rats. J Neurosci 2011; 31: Patterson T. L., Semple S. J., Zians J. K., Strathdee S. A. Methamphetamine-using HIV-positive men who have sex with men: correlates of polydrug use. J Urban Health 2005; 82: i Yin W., Hao Y., Sun X., Gong X., Li F., Li J. et al. Scaling up the national methadone maintenance treatment program in China: achievements and challenges. Int J Epidemiol 2010; 39: ii Wu Z., Wang Y., Detels R., Rotheram-Borus M. J. China AIDS policy implementation: reversing the HIV/AIDS epidemic by Int J Epidemiol 2010; 39: ii Rou K., Sullivan S. G., Liu P., Wu Z. Scaling up prevention programmes to reduce the sexual transmission of HIV in China. Int J Epidemiol 2010; 39: ii Supporting information Additional Supporting information may be found in the online version of this article at the publisher s web-site: Table S1 Variable and code for two-level logistic model.