Table 1.

Characteristics of Observational Studies (N=24)

Author	Year	Platform	Study Sample	Key Findings
Fernández et al.	2005	HMSM-oriented chatroom	171 Hispanic MSM	48.5% had used club drugs in the past 6 months (15.8% cocaine, 11.7% crystal methamphetamines, 31.6% amyl nitrites, 14% ecstasy, 3.5% gamma-hydroxybutyrate, 3.5% ketamine, and 19.3% Viagra)
Rhodes et al.	2007	Geographically defined Internet chat room and offline	1189 MSM	6% reported using methamphetamines during the past 30 days, and methamphetamine use was associated with inconsistent condom use, prior STD, HIV serostatus, and other drug use in the past 30 days.
Chiasson et al	2007	Online banner ads on 14 gay-oriented websites	1683 MSM	24.0% had used drug before sex, 4.3% had used crystal methamphetamine before sex, 7.2% used sildenafil before sex, and 7.1% used nitrite inhalants before sex.
Klein	2009	MSM-oriented website	1316 MSM seeking bareback sex	Those who identified to seek for bareback sex were more likely to indicate a desire for having sex while high.
Jenness et al.	2010	Offline recruitment	781 MSM	25% had engaged in frequent binge drinking and 33% used hard drugs. Substance use was associated with meeting partners offline.
Lea et al.	2011	Facebook, online forums, email referrals, and offline methods	572 Same-sex attracted youth (18-25)	4% reported having ever used mephedrone.
Klein	2011	Telephone survey on 16 different websites (e.g. bareback.com, rawloads.com, men4sexnow.com, and squirt.org)	332 MSM who use the internet to seek men for unprotected sex	Online participants had much higher percentage of drug use in comparison to average US population. Percent of participants who reported drug use in lifetime and in the last 30 days: cocaine (51.4, 4.5), crack (20.2, 2.4), heroin (12.4, 0.9), hallucinogens (37.5, 0), Ecstasy (36.3, 2.4), any illegal drug use other than marijuana (68.3, 23.0).
Wei et al.	2012	Gay-oriented website (www.fridae.com)	10861 MSM	16.7% reported recreational drug use in the past 6 months. Ecstasy (8.1%) and Viagra (7.9%) was the most prevalent drugs used. HIV positive MSM reported higher levels of drug use compared to HIV negative/unknown MSM.
Clark et al.	2012	Internet in general	657 HIV-positive individuals	35% of homosexual, 26% of heterosexual, and 11% of female participants have reported methamphetamine use in the past year. 29% reported using the Internet to seek sex partners. Internet-users reported having more sexual partners in the past 6 months (4 vs. 1) and higher rates of methamphetamine use (48% vs. 24%) compared to non-Internet users.
Ko et al.	2012	gay-oriented website (www.fridae.com)	1645 MSM	16.0% had used recreational drugs in the previous 6 months. Frequency of drug use was associated with the number of online sexual partners.
Wei et al.	2012	Gay-oriented website (www.fridae.com)	416 HIV-positive MSM	Non-disclosure was significantly associated with drug use before sex on a weekly basis. 40.1% have used drug before sex. 40.9% had used alcohol before sex.
Whiteley et al.	2012	Offline recruitment	1045 African American adolescents	6% met sex partners online. Online sex partner seeking was associated with drug use at last sex and cocaine use. 17.7% used alcohol at last sex, 33.9% used other drugs at last sex, 11.3% reported lifetime cocaine use.
Grov	2012	Craigslist.org	601 MSM	Men recruited from Craigslist reported the least condom use. Men from Craigslist did not show higher levels of substance use in comparison to participants recruited from bathhouses or bars/clubs. Men from Craigslist reported lifetime use of cocaine (40.1%), methamphetamine (13.1%), MDMA (27.5%), GHB (8.9%), ketamine (9.4%), and Viagra (33.2%). 39.6% reported drinking alcohol 2 or more times per week in the last 3 months.
Horvath et al.	2013	HIV-related websites, Facebook ads, online search and partnership with other organization, email to former research participants	276 HIV-positive MSM	Stimulant use is much higher in those who missed HIV medical appointments, and stimulant users also deemed HIV medical appointment to be less important (non-engagement in HIV medical care).
Young and Shoptaw	2013	Facebook	118 MSM	High rates of cocaine (17%) and methamphetamine (15.3%) usage (both over 15% in the past year), past 3 months coke (9.8%) and methamphetamine (8.9%).
White et al.	2013	Offline recruitment	197 MSM	Using internet to meet sexual partners was associated with increased odds of using powdered cocaine in the past 12 months. 24%, 17%, 14%, 6%, and 5% reported powdered cocaine, crack cocaine, poppers, crystal methamphetamine, and heroin.
Parsons et al.	2013	1) Dating sites for MSM, 2) MSM chat rooms, 3) Craigslist.org, 4) Facebook page, and 5) Facebook ads	694 MSM	Men recruited online were more likely to have tried a variety of drugs, such as methamphetamine (22.4%), cocaine (32.6%), ecstasy (16.3%), ketamine (6.6%), GHB (11.4%), poppers (42.9%), and at least one club drug (65.3%)
Grov et al.	2013	Sexual networking site	1815 MSM	Individuals surveyed online who practices group sexual encounter are more likely to use stimulants (cocaine, methamphetamine, crack), consumed alcohol (5+), spontaneous group sex.
Wilkerson et al.	2013	1) Nine mobile websites or apps used primarily by MSM to meet other men, 2) Browser friendly, 3)Email snowball, 4)Facebook page and Twitter page	343 Methamphetamine-using MSM	Social media strategy was the most effective one with no cost.
Margolis et al.	2014	Adult MSM-oriented sexual networking websites	1319 HIV-positive MSM	32% of men engaged in anal intercourse without condoms with at-risk partners, and substance use in conjunction with sex is associated with both insertive and receptive anal sex. Intercourse, any drug (71.6%), methamphetamine (28.7%), cocaine/crack (29.8%), heroin (1.7%), club/party drug (26.5%), poppers (54.9%), PDE5 inhibitors (46.2%), inject drugs (16.8%) in the past 60 days.
Montoya et al.	2014	Within-Study Recruitment	20 HIV-positive methamphetamine users	This qualitative study demonstrates the feasibility of using focus groups to derive patient-centered intervention content to address the health challenge at hand in targeted populations.
Young et al.	2014	Twitter	550+ Million General Public Twitter Users	Geolocated tweets were extracted and used to create a map displaying the geographical location of HIV-related tweets. There was a significant positive relationship (p<.01) between HIV-related tweets and HIV cases.
Mitchell	2015	Facebook-recruitment	172 HIV-positive and HIV-discordant MSM	Other than alcohol most did not use substance with sex (76.7%). At least one partner in the couple (if not both) used amyl nitrate (29.1%) and party drugs (24.4%).
Holloway	2015	MSM app-based recruitment	295 MSM	High rates of recent binge drinking (59 %), marijuana use (37 %), and illicit substance use (27 %) were observed among participants. GSN app use greater than 1 year and showing naked chest or abs in a profile picture were positively associated with recent illicit substance use.