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Chemsex drugs on the rise: a longitudinal analysis of the Swiss HIV Cohort Study from 2007 to 2017
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so much for that ART recommendation to start immediately & starting ART immediately, which usually does NOT happen, will prevent the aging & HIV crisis & the dent on Ending Aids. Jules. Plus in the USA viral suppression rates are only around 50% & 73% in WIHS cohorts & 80%+ when PLWH are engaged in care.
In conclusion, our study identified a significant increase in the use of chemsex drugs, in particular methamphetamine and GHB/GBL, among MSM diagnosed with HIV infection in Switzerland and a strong association of this use with coinfections and depression. In light of these findings, more studies in this field are needed to better understand the relationship between sexual behaviour, drug consumption and depression in order to inform successful harm reduction strategies. This further understanding will not only help our patients and potentially decrease numbers of other STIs, including viral hepatitis C, but will also be crucial to our understanding of the current drivers in the ongoing HIV epidemic.
When MSM and non‐MSM were analysed separately, we found a large disparity in recreational drug use over time between the two groups: for MSM, there was a significant increase in overall drug consumption, whereas for non‐MSM there was a decrease. This increase remained significant when less harmful illicit drugs were excluded. The most relevant finding is the 12‐fold increase in methamphetamine use and the > 3‐fold increase in GHB/GBL use. Unfortunately, the SHCS questionnaire does not ask about the setting in which a substance is consumed. However, we observed a significant association between the consumption of these recreational drugs and indicators for risky sexual behaviour, namely condomless anal sex with occasional partners and a high prevalence of HCV infection and syphilis. These findings indicate that the chemsex trend has reached Switzerland, and is most prevalent in the region of Zurich. Our study shows a strong association between depression and the use of all analysed substances. It is well known that depression can lead to a greater tendency to take more sexual risks 21.
Many of the drug classes considered were predominately taken by MSM, such as XTC/MDMA, GHB/GBL, ketamine and methamphetamine (Fig. 1). Data on reported drug use from 5657 MSM for the years 2007-2017 show that 2510 (44.4%) reported drug use at least once during the study period and, if we exclude cannabis, amyl nitrite, benzodiazepines and other prescription drugs, the number remains high at 1468 or 25.9% of all MSM in the study. Analysis of the time trend for chemsex drugs and other potentially sex‐enhancing drugs revealed an increase in the use of all these substances (Fig. 2b). In particular, when comparing the years 2007 and 2017, we observed an increase in the use of GHB/GBL (from 1.0 to 3.4%; P for trend < 0.001), methamphetamine (from 0.2 to 2.4%; P for trend < 0.001), ketamine (from 0.1 to 0.7%; P for trend = 0.016), mephedrone (from 0.0 to 0.2%; P for trend = 0.006), cocaine (from 6.2 to 9.9%; P for trend < 0.001), XTC/MDMA (from 3.2 to 5.3%; P for trend = 0.0014) and amphetamine (from 0.4 to 1.0%; P for trend < 0.001).
Most participants reporting drug use were from the study centre in Zurich (Fig. 3). The total number of participants reporting drug use in the seven SHCS centres as well as patient characteristics can be found in Table 1. A significant association between drug intake and condomless sex with occasional partners was found for the five substances of interest, namely methamphetamine, GHB, cocaine, XTC/MDMA and amphetamine, compared to those MSM not using sex‐enhancing drugs (Table 1; Fig. 4). All subgroups of drug classes had a significantly higher prevalence of depression. Moreover, adherence to ART was significantly lower for users of GHB/GBL, cocaine and amphetamine compared to the control group. HCV infection and syphilis were more frequent among drug users for all five drug classes considered (Table 1).
As our study is the first to provide longitudinal data on recreational drug use among MSM living with HIV, our results are difficult to compare with those of other studies in the field. However, the study suggests that the use of chemsex drugs among MSM living with HIV seems to be lower in Switzerland than in the UK 5.
Chemsex drugs on the rise: a longitudinal analysis of the Swiss HIV Cohort Study from 2007 to 2017
18 December 2019

Chemsex refers to the use of sex‐enhancing drugs among men who have sex with men (MSM) in combination with specific sexual and social behaviours. Longitudinal data on this development and the associated health risks are scarce.
Data on all recreational drugs reported in the Swiss HIV Cohort Study (SHCS) from 2007 to 2017 were collected. Drug use was analysed longitudinally for all drug classes. In addition, potential associations between patient characteristics and the consumption of methamphetamine, γ‐hydroxybutric acid/γ‐butyrolactone (GHB/GBL), 3,4‐methylenedioxymethamphetamine (MDMA/XTC), cocaine and amphetamine were analysed.
We analysed 166 167 follow‐up entries for 12 527 SHCS participants, including 7101 free text field entries containing information about recreational drugs other than cannabis, cocaine and heroin. Overall, we observed a stable percentage (9.0%) of recreational drug use (excluding cannabis, amyl nitrite and prescription drugs). For MSM, however, there was an increase in overall drug use from 8.8% in 2007 to 13.8% in 2017, with particularly large increases for methamphetamine (from 0.2 to 2.4%; P < 0.001) and GHB/GBL (from 1.0 to 3.4%; P < 0.001). The use of each of the potentially sex‐enhancing drugs methamphetamine, GHB/GBL, cocaine, XTC/MDMA and amphetamine was significantly associated with condomless sex with nonsteady partners, and higher prevalences of depression, syphilis and hepatitis C.
The significant increase in the use of chemsex drugs among MSM in the SHCS and the strong association with coinfections and depression highlights the need for harm reduction programmes tailored to MSM. According to our results, improving knowledge about recreational drugs is important for all health care professionals working with people living with HIV.
Study population and overall drug use in the SHCS

During the study period 2007-2017, information on cocaine, cannabis and heroin use was available for 12 527 SHCS participants, of whom 5657 (45.2%) were MSM and 6870 (54.8%) were non‐MSM (female or heterosexual male). Almost half of all MSM were registered in Zurich (47.2%). Information from 166 167 total visits was available, and, of those, only 2086 (1.3%) visit entries did not contain any information about drug use. Overall, 1840 (14.7%) of the participants reported substance use in the free text field. In detail, we could identify 7101 substances reported at 5840 follow‐up visits from these 1840 participants. In total, we identified 408 different spellings of substances reported (see Appendix 1). Overall, 4686 (37.4%) of all SHCS participants reported the intake of any kind of recreational drug at least once during the study period. Excluding cannabis, amyl nitrite, benzodiazepines and other prescription drugs, 2560 (20.4%) of the SHCS participants reported having taken recreational drugs in this period. See Fig. 1 for a summary of the drug classes considered.
To elucidate the changes in drug use over time, we analysed the typical chemsex drugs GHB/GBL, methamphetamine, ketamine and mephedrone, but also other potentially sex‐enhancing drugs used in the SHCS, namely cocaine, XTC/MDMA and amphetamine. We looked at the percentage of SHCS participants using the drugs at least once in each year (Fig. 2a). In addition, we looked at the time trend of the proportion of participants reporting drug use, again excluding cannabis, amyl nitrite, benzodiazepines and other prescription drugs. This proportion remained stable, with 9.0% of participants reporting drug use (range 8.6, 9.5%; P for trend = 0.57). However, in contrast to the whole SHCS population, there was a significant increase (P for trend < 0.001) towards more drug use among MSM: the report of drug use increased from 8.8% to 13.8% from 2007 to 2017 (Fig. 2b). For non‐MSM, we observed the opposite trend (P for trend < 0.001), namely 9.8% reporting drug use in 2007 and 5.7% reporting drug use in 2017 (Fig. 2c).
A growing number of reports across multiple countries show a new trend of sex‐enhancing drug use among men who have sex with men (MSM), often referred to as chemsex 1-3. Chemsex defines a syndemic of specific social and sexual behaviours associated with specific recreational drugs (‘chems’) among MSM before or during sex, wide use of geosocial networking applications (apps) and sex with a high number of partners in a mostly private setting 1, 2. Drugs often referred to as chemsex drugs typically include N‐methylamphetamine (methamphetamine), 4‐methyl methcathinone (mephedrone), γ‐hydroxybutyric acid/γ‐butyrolactone (GHB/GBL) and sometimes ketamine 1, 2. For Switzerland, in 2010 the European MSM Survey (EMIS) showed that all of these drugs were already in use by MSM and that 7% of MSM in Zurich reported use of GHB/GBL, ketamine, methamphetamine or mephedrone in the previous 4 weeks 3. Despite this, the Swiss Federal Office of Public Health (FOPH) in 2015 concluded that there was no significant methamphetamine usage in Switzerland 4; however, their analysis did not focus on the HIV‐positive population or MSM.
In addition to the direct risk of bloodstream transmission of HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) infection through needle sharing associated with recreational drug use (RDU), RDU itself has been well studied as a risk factor for sexually transmitted infections (STIs) as a consequence of the associated increase in risky sexual behaviours such as condomless sex and having a high number of sexual partners 5-8. The availability of new substances and the change in sexual behaviour resulting from the use of geosocial networking apps come with new challenges for health care professionals, such as prevention and treatment of infectious and psychiatric diseases 9-11. This change in sexual behaviour might also be one reason for the growing number of STIs among MSM 12, 13. The extent of this new development has, to date, not been well studied longitudinally.
The aim of this study was to analyse the trend in the consumption of all recreational drugs over the last 11 years among all participants in the Swiss HIV Cohort Study (SHCS), with a particular focus on the use of chemsex drugs and other potentially sex‐enhancing drugs among MSM. In addition, we compared characteristics of participants who reported using recreational drugs (excluding cannabis, amyl nitrite and prescription drugs) at least once during the study period to those of participants who did not report RDU at any follow‐up visit.
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