San Francisco Department of Public Health, San Francisco, CA, USA.
Received: 7 February 2002; accepted: 13 February 2002.
The potential role of sildenafil (Viagra) in the risk of HIV and sexually transmitted disease (STD) transmission was evaluated among gay or bisexual men seeking public STD services in San Francisco. Viagra users reported greater numbers of recent sex partners, higher levels of unprotected anal sex with an HIV-positive partner, and higher rates of prevalent STD than non-users. Moreover, mixing Viagra with illicit drugs was commonly reported. Further studies are needed to determine whether a causal role exists.
Sildenafil (Viagra), an oral treatment for erectile dysfunction in men, may be associated with unsafe drug use and sexual risk behavior [1–3]. The potential role of Viagra in the resurgence of new sexually transmitted disease (STD) and HIV transmission in San Francisco was investigated among men seeking public STD services in San Francisco from December 2000 to February 2001. A one-page confidential survey on Viagra use and related risk behavior was distributed to a convenience sample of 844 male patients at clinic registration. Survey data were linked to a computerized clinic database using a unique medical record number.
The majority of participants were heterosexual (57%) (480/844); however, (42%) (352/844) were gay or bisexual. The median age of participants was 32 years (range 17–71). Participants were more likely to be white (60%) rather than black (19%), Latino (12%), or other races (9%).
Overall, 17% (143/844) of study participants reported using Viagra in the past year. Gay or bisexual men (31%) (108/352) were significantly more likely to use Viagra compared with heterosexual men (7%) (35/480) (P < 0.01). Because Viagra use occurred primarily among gay or bisexual men, further analysis focused on this sub-population (n = 352). Among those gay or bisexual men who used Viagra (n = 108), over half received the drug from a friend (56%) rather than a healthcare provider (42%) or other sources such as the Internet (2%). The use of Viagra in combination with illicit drugs such as ecstasy (43%), methamphetamines (28%), amyl nitrate (poppers) (15%) and ketamine (8%) was common.
HIV-positive gay or bisexual men were slightly more likely to have used Viagra in the past year (39%) (26/67) compared with HIV-negative men (29%) (66/226) (P = 0.1) (Table 1). The prevalence of STD (gonorrhea, chlamydia or syphilis infection) at the survey visit was somewhat greater in Viagra users than non-users (32 versus 23%, P = 0.09). HIV-positive Viagra users had significantly higher proportions of current STD infection compared with HIV-positive non-users (50 versus 26%, P = 0.05).
Viagra users had a higher number of sex partners (anal and oral sex) in the past 2 months compared with non-users (mean 5.4 versus 3.5, P < 0.01). Among HIV-negative men who reported having anal sex partners in the past 2 months, a greater percentage of Viagra users reported recent unprotected serodiscordant anal sex (sex with a partner of opposite or unknown HIV serostatus) compared with non-users (30 versus 15%, P = 0.03).
A subanalysis conducted on gay or bisexual men who mixed Viagra with other drugs (n = 52) found that ‘mixers’ were significantly more likely to be less than 35 years old (69 versus 25%, P < 0.01), to have received Viagra from a friend (73 versus 39%, P < 0.01), and believed that combining Viagra with other drugs enhanced the sexual experience (73 versus 25%, P < 0.01). Viagra mixers reported a greater number of sex partners in the past 2 months than those who did not mix Viagra with other drugs (mean 5.5 versus 2.8, P < 0.01). HIV-negative Viagra mixers (n = 31) were significantly more likely to report unprotected anal sex with a serodiscordant partner (44 versus 16%, P = 0.03) compared with HIV-negative men who used Viagra alone (n = 35).
One in three gay male STD clinic patients in San Francisco had used Viagra in the past year. Although Viagra is a drug that should only be taken under the direct supervision of a healthcare provider, over half of the men received the drug from a friend. Significantly higher levels of risk for STD and HIV transmission were observed among Viagra users, including a higher prevalence of STD, an increased number of sex partners, and among HIV-negative men more recent unprotected serodiscordant anal sex. Moreover, a substantial proportion of Viagra users had combined Viagra with other drugs, including 15% of Viagra users who had also concomitantly used amyl nitrate (`poppers'), which is a life-threatening contraindication.
As a result of the cross-sectional nature of the study, direct causal inference about the risk of HIV and STD transmission secondary to Viagra use cannot be made. Using logistic regression, Viagra use was found to be independently associated with an increased number of partners and was also associated with having a prevalent STD after controlling for the number of partners. Whether these associations were found because Viagra enabled men to have more partners, increased the duration of sexual exposure to infected partners, or was a marker for higher risk sexual networks cannot be determined from the data. In addition, we did not ascertain the direction of unprotected serodiscordant anal sex (i.e. insertive or receptive) to determine the risk of HIV transmission. Finally, considering the high-risk behaviors common in our study sample, our estimates are likely to be elevated compared with other gay or bisexual men.
Despite these limitations, our data highlight a significant relationship between Viagra use and sexual risk behaviors, drug use, and new STD among a sample of gay or bisexual men in San Francisco. These findings are consistent with other studies of STD, HIV, and drug-related risk behaviors among gay men using Viagra [2,4], and provide compelling information on the potential role that Viagra may play in the transmission of new HIV infections and STD among gay or bisexual men in San Francisco . It is incumbent on the manufacturer of Viagra and prevention health educators to inform gay or bisexual men of the risks of Viagra use taken outside of medical supervision, and to work with medical providers to ensure risk-reduction counselling along with the safe and proper use of this valuable drug.
Andrea A. Kim
Charlotte K. Kent
Jeffrey D. Klausner
The authors would like to acknowledge Ms Toni Butler and the clinic registration staff at the San Francisco municipal sexually transmitted disease clinic for their invaluable efforts with the implementation of this survey. They would also like to thank personally all the participants of this survey who contributed their time and personal experiences to further the knowledge of Viagra use among men in San Francisco.
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