Objectives: The influence of partner type and risk status on the unprotected sexual behavior of young men living with HIV (YMLH) who have sex with men is examined.
Methods: Sexual behavior and sexual partner characteristics of 217 YMLH recruited from adolescent care clinics in 4 AIDS epicenters (Los Angeles, San Francisco, New York, and Miami) were assessed. YMLH were categorized by sexual behavior pattern, and sexual partners were classified by type and risk status. Generalized linear modeling employing overdispersed Poisson distribution was used to analyze the effect of partner type and partner risk status on unprotected sex acts.
Results: Most YMLH (62%) reported multiple partners, 26% reported 1 sexual partner, and 12% reported abstinence in the past 3 months. Approximately 34% of polygamous and 28% of monogamous youth engaged in unprotected sex. Monogamous youth were most likely to have unprotected sex with HIV-positive partners. Polygamous youth were most likely to have unprotected sex with HIV-positive partners, irrespective of whether the partner was regular or casual. For polygamous YMLH, unprotected sex did not differ among single-time/new partners with different risk levels.
Conclusions: Partner characteristics influence the condom use behavior of YMLH. YMLH make decisions regarding condom use based on perception of their partner's risk. Preventive interventions must include skills for acquiring accurate information about partner risk status and education regarding the health risks of unprotected sex with HIV seroconcordant partners.
From the *Center for HIV Identification, Prevention, and Treatment Services, AIDS Institute, Department of Psychiatry, University of California, Los Angeles, Los Angeles, CA; and †Faculty of Social Work, University of Toronto, Toronto, Ontario, Canada.
Received for publication April 15, 2004; accepted June 11, 2004.
Supported by grant R01 DA-07903 from the National Institute on Drug Abuse.
Reprints: Marguerita Lightfoot, 10920 Wilshire Boulevard, Suite 350, Los Angeles, CA 90024 (e-mail: firstname.lastname@example.org).
Young people are the fastest growing group of persons living with HIV (PLH) in the United States, with half of new HIV infections occurring among young people less than 25 years of age.1 By 2001, 31,000 cases of AIDS and an additional 23,000 HIV infections among 13- to 24-year-olds were reported.1 The actual number of youth living with HIV in the United States is likely to be much larger because of variable reporting procedures and limited early detection; estimates range between 110,000 and 250,000.2,3 Young men who have sex with men (MSM) are at high risk for HIV infection, particularly African Americans and Latinos. In a study of young MSM in 7 cities, more than 10% were infected with HIV, with rates of 15% among Latinos and 30% among African Americans.4
Recent increases in sexually transmitted diseases (STDs) among MSM5-10 may presage rising HIV seroincidence among young MSM. Because an increasing number of young MSM are HIV-positive and PLH are living longer because of highly active antiretroviral therapy (HAART),11 it is vital to examine the factors influencing sexual risk behaviors among young men living with HIV (YMLH) who have sex with men if we are to regulate the health of this population effectively and mitigate the further spread of HIV. Two factors that influence the sexual risk behavior of MSM have emerged from the literature: partner type and partner risk status. This article examines the relation of partner type and perceived risk status on the sexual behavior of YMLH.
A growing literature suggests that partner type influences the sexual risk behaviors of MSM.12-18 HIV-seronegative MSM tend to engage in higher levels of unprotected sex with their regular or primary partners as compared with casual or single-time partners.13,16,17,19 Among the relatively few investigations of the effects of partner type on the sexual behaviors of HIV-seropositive MSM, results are mixed. Semple et al20 suggest that HIV-seropositive MSM engage in more unprotected sex with steady and single-time partners than casual partners, whereas other researchers have found no differences in sexual behaviors by partner type among HIV-seropositive MSM.21-24
Increasing evidence indicates the importance of a partner's risk status, particularly HIV serostatus, in understanding sexual risk behaviors among HIV-positive MSM.14,19,25,26 It is possible that the apparent lack of effect of partner type on unprotected sex among HIV-positive MSM may be explained by the partner's risk status. Several studies suggest that HIV-positive MSM are more likely to engage in unprotected sex with partners reported to be HIV-positive than with uninfected partners regardless of partner type,14,22,25,27-31 but 2 studies found no difference in unprotected sex by partner HIV serostatus.21,22 A few studies focusing on YMLH have suggested trends in greater unprotected sex with partners with nonprimary HIV-negative or unknown serostatus as opposed to primary partners, but the results failed to achieve significance.20,22,32
Despite growing evidence on the influence of partner type and partner serostatus, few investigations have assessed the effects of interactions between partner type and partner HIV serostatus on sexual risk behaviors among MSM living with HIV. A recent meta-analysis of investigations of sexual risk behaviors of PLH revealed that 75% of the 61 studies (largely among MSM) did not specify the HIV serostatus of sex partners,33 thus making it impossible to assess the interaction of partner type and serostatus. Furthermore, there has been little investigation of the partner's other risk behaviors (eg, injection drug use, survival sex) in the sexual decision making of MSM. Thus, the effect of partner serostatus and partner risk, including partner type, on the sexual behaviors of HIV-positive MSM remains unclear.
Sexual risk behaviors of YMLH are even less well understood than those of adults, because the majority of investigations of seropositive MSM have focused on adults. Given the disproportionate HIV incidence and prevalence among young MSM and high levels of unprotected sex among young MSM,19,34,35 particularly with their primary partners,23 it is crucial to assess the influence of partner type and risk status on the unprotected sexual behaviors of YMLH. Therefore, we examined the sexual behavior patterns and influence of partner type and partner serostatus on the unprotected sexual behaviors of YMLH.
Participants were recruited from 9 adolescent clinical care sites in 4 AIDS epicenters (Los Angeles, San Francisco, New York, and Miami). The adolescent clinical care sites were similar across cities, comprehensively providing medical care and social services. Over a 21-month period from 1994 to 1996, 393 youth living with HIV were approached for recruitment. Of those 393, 25 (6.4%) refused and 17 (4.3%) were too ill to participate. One participant was excluded from the analysis because he turned 25 years old between the time of recruitment and baseline assessment. Consequently, the total sample included 350 participants. Among the eligible 350 participants, 253 (72.3%) were male and 219 (87%) identified as gay or bisexual. Two participants did not complete most scales in the assessment and were excluded from the current analysis (final n = 217). The institutional review boards at each university approved all procedures. Parental consent was obtained for youth younger than 18 years of age who were not emancipated. Each youth received $25 for completing a 2.5-hour assessment.
Data were collected by a trained and diverse interview team. Interviewers were trained in a variety of areas, including psychosexual and substance use assessments, sexual abuse reporting, research ethics, and emergency procedures. Interviews were conducted using computerized assessment personal interviews. All interviews were audiotaped, and quality assurance ratings were conducted on a random sample of tapes; 91% met criteria on ratings of completeness, positive tone, and crisis referrals.
Participants reported their sexual behavior in the previous 3 months and reported detailed information for up to 5 specific partners. A sexual partner was defined as a male or female partner with whom the participant engaged in vaginal or anal sex. The number of sexual encounters, condom use, and alcohol and drug use during sex with each partner was measured. Information about each partner's gender, age, and type and perceived knowledge about the partner's risk behaviors were also collected.
Sexual Behavior Pattern
Youth were classified as abstinent, monogamous, or polygamous based on their sexual behavior in the past 3 months. Youth were classified as abstinent if they reported no sex; monogamous if they reported only 1 regular sexual partner; or polygamous if they reported having casual, new, single-time, or multiple sexual partners.
Type of sexual partner was classified into three categories: (1) a regular partner, someone the youth had sex with on an ongoing basis; (2) a casual partner, someone the youth knew and had sex with occasionally; and (3) a new or single-time partner, someone the youth had sex with for the first time during the past 3 months and planned to have sex with again or someone they had sex with once and did not plan to have sex with again.
Partner's Perceived Risk
The self-reported perception of partner's risk was classified into 3 categories: (1) HIV-positive, partner is believed to be HIV-positive; (2) high risk, partner is not HIV-positive and has used intravenous drugs, engaged in survival/commercial sex, or had an STD in the past 3 months; and (3) low risk, partner has none of the above.
Substance Use During Sex
For each sexual act, YMLH reported whether drugs or alcohol had been used. The use of alcohol or drugs during sex was classified as a dichotomous variable: (0) did not use or (1) used at least once.
The YMLH reported 4 indicators of physical health: (1) self-report of HIV diagnostic status (HIV symptomatic, HIV asymptomatic, or AIDS); (2) T-cell count; (3) physical health symptoms, calculated as a summary count of 23 physical symptoms (= 0.88); and (4) physical health distress, calculated as the mean of distress across all symptoms ( not at all distressed to  extremely distressed).
The Brief Symptom Inventory (BSI)36 was administered to assess emotional distress. The BSI provides a global estimate of emotional distress (α = 0.97). The BSI also provides normative data to determine a clinical cutoff level that approximates having a diagnosable psychiatric disorder.
Problem behavior was measured using a 27-item delinquency scale based on the Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., revised (DSM III-R) conduct disorder criteria. Youth indicated whether they had committed any of the delinquent acts. The number of positive endorsements was summed to compute a score of problem behaviors.
Comparisons of baseline characteristics of 217 YMLH between the 3 behavior groups (abstinent, monogamous, and polygamous) were calculated with ANOVA for the continuous variables and with the χ2 test for the categoric variables. Sexual behaviors with each partner were compared with a generalized linear model using overdispersed Poisson distribution for the counts and overdispersed binomial distribution for the percentages, with consideration of multiple partners.
For the 57 monogamous participants, a generalized linear model using overdispersed Poisson distribution was chosen to compare the number of unprotected sexual acts among participants with 3 different types of perceived risk about the partner. Because of the small sample sizes in the categories of perceived knowledge, other covariates were not considered in the model.
For the 134 polygamous participants, the analysis was conducted to investigate the effect of partner type and the partner's perceived risk on unprotected sexual behaviors. Because the sexual behavior outcome (number of unprotected sexual acts) was measured as counts and participants reported more than 1 partner, the generalized linear model for the overdispersed Poisson distribution was applied using generalized estimating equations (GEEs).37 Key independent variables were the type of partner, perceived partner's risk, and interactions between them. Age, problem behavior score, BSI score, and substance use during sex were included as covariates. Ethnicity, the number of partners, the number of physical health symptoms, and the physical health distress score were not significant and were removed in the final model.
As illustrated in Table 1, 62% of YMLH reported multiple partners. About a fourth of youth (26%) reported 1 sexual partner, and 12% reported abstinence in the past 3 months. The mean age of youth was 21.4 years old (range: 15-24 years). Most youth were Latino (45%) or African American (18%). Youth were not recruited evenly across the 4 cities. In part, this reflects the different epidemics in Los Angeles and Miami; most HIV-positive youths recruited in Miami were young women (63.3%), and only MSM were included in this analysis.
Compared with youth who reported abstinence, distress with one's physical health symptoms was significantly higher among those demonstrating a polygamous pattern (1-way ANOVA; Tukey test, P = 0.009) and those demonstrating a monogamous pattern (1-way ANOVA; Tukey test, P = 0.086). HIV diagnostic status, T-cell count, and the number of physical health symptoms were unrelated to the behavioral pattern, however.
Reports of problem behavior were significantly higher among youth reporting a polygamous pattern (1-way ANOVA; Tukey test, P = 0.0325) in comparison to those reporting a monogamous pattern.
For all groups, levels of emotional distress were not significantly different from each other or the normative data.38
Sexual Behavior Pattern
Approximately 34% of polygamous and 28% of monogamous youth engaged in unprotected sex. Table 2 shows that the lifetime median number of partners was significantly higher among youth who reported polygamy or abstinence in contrast to monogamous youth (1-way ANOVA applied to ranks; Tukey test, P <0.001).
The estimated mean number of unprotected sex acts was 2 times higher in the monogamous group compared with the polygamous group (GEE, 95% confidence interval: 1.07-5.53; P = 0.033). Over a third (35%) of all sex involved substance use. For polygamous youth, the number of unprotected sex acts was 3.5 times higher when alcohol or drugs were used during sex (GEE, 95% CI: 1.48-8.50; P = 0.005) and tended to be higher for youth who reported more delinquent acts (GEE, 95% CI: 0.92-3.90; P = 0.084; scores log-transformed to accommodate for skewed distribution).
For monogamous YMLH (n = 57), almost half of sex acts (42%) were with partners perceived to be at low risk and youth used a condom with most of those partners (mean unprotected sex acts = 1.25, SD = 3.42; Fig. 1). In contrast, the mean number of unprotected sex acts was 7.3 (SD = 12.92) with HIV-positive partners. The estimated number of unprotected sex acts was 6 times higher among partners perceived as HIV-positive compared with partners perceived as low risk (Poisson model; χ2 (1) = 5.40, P = 0.020) and 11 times higher when compared with partners perceived as high risk (Poisson model; χ2 (1) = 5.21, P = 0.022). The estimated number of unprotected sex acts was similar when monogamous youth perceived partners as high or low risk. Monogamous youth were most likely to have unprotected sex with HIV-positive partners.
Among the 398 partners of the 134 polygamous youth, the relation between type of partner, perceived risk of partner, and condom use was more complex and is summarized in Figures 2 and 3.
Partner Type and Partner Risk
Although youth perceived their regular partners as equally likely to be seropositive, high risk, or low risk, casual partners were twice as likely to be perceived as high risk (65%) and only 10% were perceived as low risk (see Fig. 2). New or single-time partners were also twice as likely to be perceived as high risk (59%), although they were least likely to be perceived as being HIV-positive. The more casual the sexual relationship, the greater was the likelihood that polygamous youth perceived their partner to be at risk.
Unprotected Sex and Partner Type
The estimated number of unprotected sex acts for polygamous youth with regular partners was 5 times higher than with casual partners (GEE, 95% CI: 2.08-12.19; P < 0.001) and 12 times higher than with single-time or new partners (GEE, 95% CI: 5.86-26.05; P <0.001). The estimated number of unprotected sex acts with casual partners was 2.5 times higher than with single-time or new partners (GEE, 95% CI: 0.85-7.06; P = 0.096). Examining only partner type, youth are most likely to have unprotected sex with a regular partner.
Unprotected Sex and Partner Risk
The estimated number of unprotected sex acts with partners perceived as HIV-positive was 7 times higher when compared with partners perceived as being high risk (GEE, 95% CI: 3.36-12.78; P < 0.001) and 5 times higher compared with partners perceived as being low risk (GEE, 95% CI: 1.74-16.21; P = 0.003). The estimated number of unprotected sex acts for casual and single-time/new partners was similar for partners perceived as being high or low risk. Considering partner risk only, youth are most likely to have unprotected sex with an HIV-positive partner.
Unprotected Sex, Partner Type, and Partner Risk
As illustrated in Figure 3, the estimated number of unprotected sex acts with partners perceived as HIV-positive was 32 times higher than with partners perceived as high risk (χ2  = 37.1, P < 0.001). The estimated number of unprotected sex acts with partners perceived as low risk was 11 times higher than with partners perceived as high risk (χ2  = 8.76; P = 0.003). The estimated number of unprotected sex acts with partners perceived as HIV-positive was not significantly different from that with partners perceived as low risk. Youth are most likely to have unprotected sex with regular partners who are HIV-positive or perceived as low risk.
The estimated number of unprotected sex acts with partners perceived as HIV-positive was almost 8 times higher than with partners perceived as high risk (χ2  = 10.39, P = 0.001) and 18 times higher than with partners perceived as low risk (χ2  = 5.95; P = 0.015). The estimated number of unprotected sex acts with partners perceived as high risk was not significantly different from that with partners perceived as low risk. Youth are most likely to have unprotected sex with casual partners they believe to be HIV-seropositive.
Single-Time and New Partners
For single-time and new partners, the estimated number of unprotected sex acts was not significantly different among partners with different levels of perceived risk.
Most (62%) YMLH reported a polygamous sexual pattern in the past 3 months. YMLH reporting a polygamous sexual pattern also reported a significantly higher median number of lifetime sexual partners, and a third of polygamous youth reported 5 or more sexual partners in the previous 3 months. These data suggest that the young men's recent sexual pattern reflects a probable lifetime pattern of sexual behavior.
Unprotected sex was highest among monogamous youth. The number of unprotected sex acts was 2 times higher in the monogamous group compared with the polygamous group. Although the literature is mixed regarding the effect of partner type on the sexual behaviors of HIV-seropositive MSM,33 these findings are consistent with reports in the literature indicating elevated rates of unprotected sex with primary partners for the general MSM population.12,25 In addition, although the greatest number of sex acts for monogamous youth occurs with low-risk partners, YMLH have the most unprotected sex with HIV-seropositive partners. Youth are having protected sex with partners they perceive as HIV-seronegative, regardless of whether the partner is perceived as low or high risk. These findings suggest that the monogamous youths' primary motivation is to protect their partner and they make decisions about protected sex that reflect efforts to reduce transmission risk. Similarly, YMLH are selectively choosing to have unprotected sex with other HIV-positive men, where transmission of HIV may be perceived as less of a concern. These young men are placing themselves at risk for contracting other STDs, however, which could accelerate HIV disease progression.39,40
For polygamous youth, the more casual the sexual relationship, the more likely it was that the partner was viewed as risky. Polygamous youth seemed to recognize that they may not accurately discern the risk status of casual sexual partners. Consequently, with casual partners, youth are conservative and assume the partner is risky. This assumption seems to be important when examining the relationship between partner type, partner risk, and unprotected sex.
The pattern for polygamous youth is the same as for monogamous youth for protected sex with regular and casual partners. For regular partners, the amount of unprotected sex was similar for HIV-seropositive and low-risk partners. Similarly, for casual partners, youth engaged in unprotected sex with casual partners who they believed to be HIV-seropositive at a rate much higher than with either high- or low-risk partners. For youth with multiple sexual partners, transmission risk remains an important factor in their decision regarding unprotected sex. With HIV-seropositive partners, where risk of transmission of HIV is not a concern, youth are engaging in unprotected sex. In general, where transmission is a concern, with HIV-seronegative partners, youth are using condoms. Interestingly, unlike monogamous youth, polygamous youth reported higher levels of unprotected sex with regular partners at low risk. Additional research is needed to explore the sexual decision making of polygamous youth further, particularly with regular partners.
Partner type does not affect decisions regarding protected sex when the partner is a single-time or new partner. For single-time or new partners, the number of unprotected sex acts was similar regardless of the partner's risk status. For partners without an established sexual relationship with the YMLH, the YMLH do not rely on their perception of risk or HIV status. Consequently, unprotected sex does not increase with HIV-seropositive partners. Again, YMLH seem motivated to protect their sexual partners and themselves.
In comparison to polygamous YMLH, more monogamous participants indicated that their sexual partners were HIV-seropositive (46% vs. 24%). In further examining disclosure of HIV status to sexual partners, we found that for monogamous participants, if they believed their partner was HIV-seropositive, they disclosed their own HIV status all the time. This compares with disclosing HIV status to 80% of sex partners when the partner is at high or low risk. For polygamous youth, the disclosure pattern was similar across partner types. Whether the partner was regular, casual, or single-time/new, YMLH disclosed their own HIV status at a much higher rate to HIV-seropositive partners than to partners perceived as high or low risk. These data suggest that disclosure of HIV status is more likely to occur when YMLH perceive their partner to also be HIV-seropositive. It is unclear from these data when disclosure occurred, however, whether it was before or after the sexual encounter. Nevertheless, these data suggest that YMLH are not disclosing their HIV serostatus to sexual partners with an unknown HIV serostatus. Although YMLH are practicing safer sex with partners of unknown status, unprotected sex with these partners still occurs. This has implications for the spread of HIV into the uninfected MSM population and the need for interventions targeted at YMLH to reduce sexual risk behaviors.
The limitations of this study should be recognized. For the analysis with monogamous partners, covariates could not be included in the analysis because of the small sample size. Therefore, other variables, such as age or substance use, were not accounted for in the statistical modeling for monogamous youth. For polygamous youth, a number of sociodemographic variables, such as age, depression, and substance use, were included as covariates in the model. We did not examine how these variables may act as moderators between the variables of interest, however. Also, we did not collect data regarding the knowledge and attitudes that may affect the youths' sexual decision making. For example, we did not collect data on knowledge about STDs and their impact on HIV disease progression or HIV superinfection, both of which may play a role in the sexual decision making of these young men.
Despite these limitations, this study has important implications. Our findings suggest that partner characteristics influence the condom use behavior of YMLH. These young men are practicing safer sex with partners who they do not want to infect and not using condoms with partners with whom transmission risk is less concerning. This is troublesome, because it is questionable whether the youth can truly know a partner's risk or HIV status or rely on a regular partner to be monogamous. Furthermore, these young men are putting themselves at significant risk for infection with an STD, which could have detrimental effects on their own disease progression.
Interventions that target YMLH must address the complex issues in making decisions regarding condom use. Interventions would need to focus on techniques for acquiring information from sexual partners to make a more informed decision. Interventions should also reinforce the altruism that YMLH feel toward protecting their partners. Consequently, there is a need to develop prevention strategies that involve couple-oriented and social network models, and recent efforts have been promising.41,42 YMLH are engaging in unprotected sex with other seropositive partners. Thus, interventions for YMLH must include education about transmission risk for STDs and the detrimental impact of other STDs on their own disease progression. In summary, although these young men continue to have unprotected sex, they are making important decisions to protect themselves and others. Prevention programs must focus on promoting good decisions.
1. Centers for Disease Control and Prevention. HIV/AIDS Surveillance Report.
Atlanta: Centers for Disease Control and Prevention; 2001.
2. Rotheram-Borus MJ, O'Keefe Z, Kracker R, et al. Prevention of HIV among adolescents. Prev Sci.
3. D'Angelo LJ, Brown R, English A, et al. HIV infection and AIDS in adolescents. J Adolesc Health.
4. Valleroy L, Secura G, Mackellar D, et al. High HIV and risk behavior prevalence among 23-29 year old men who have sex with men in 7 US cities [abstract 211]. Presented at the 8th Conference on Retroviruses and Opportunistic Infections, Chicago, February 2001.
5. Centers for Disease Control and Prevention. Resurgent bacterial sexually transmitted disease among men who have sex with men-King Country, Washington, 1997-1999. MMWR.
6. Centers for Disease Control and Prevention. Need for sustained HIV prevention among men who have sex with men. Fact sheet; 2002. Available at: http://www.cdc.gov/hiv/pubs/facts/msm.pdf
. Accessed December 1, 2002.
7. Centers for Disease Control and Prevention. Increase in unsafe sex and rectal gonorrhea among men who have sex with men-San Francisco, California, 1994-1997. MMWR.
8. Centers for Disease Control and Prevention. Outbreak of syphilis among men who have sex with men-Southern California, 2001. MMWR.
9. Chen JL, Callahan DB, Kerndt PR. Syphilis control among incarcerated men who have sex with men: public health response to an outbreak. Am J Public Health.
10. Do AN, Hanson DL, Dworkin MS, et al. Risk factors for and trends in gonorrhea incidence among persons infected with HIV in the United States. AIDS.
11. Vittinghoff E, Douglas J, Judson F, et al. Per-contact risk of human immunodeficiency virus transmission between male sexual partners. Am J Epidemiol.
12. Bosga MB, de Wit JB, de Vroome EM, et al. Differences in perception of risk for HIV infection with steady and non-steady partners among homosexual men. AIDS Educ Prev.
13. Dawson JM, Fitzpatrick RM, Reeves G, et al. Awareness of sexual partners' HIV status as an influence upon high-risk sexual behavior among gay men. AIDS.
14. Hoff CC, Stall R, Paul J, et al. Differences in sexual behavior among HIV discordant and concordant gay men in primary relationships. J Acquir Immune Defic Syndr Hum Retrovirol.
15. Kippax S, Crawford J, Davis M, et al. Sustaining safe sex: a longitudinal study of a sample of homosexual men. AIDS.
16. Moreau-Gruet F, Jeannin A, Dubois-Arber F, et al. Management of the risk of HIV infection in male homosexual couples. AIDS.
17. Myers T, Allman D, Calzavara L, et al. Gay and bisexual men's sexual partnerships and variations in risk behaviour. Can J Hum Sex.
18. Wagner GJ, Remien RH, Carballo-Dieguez A. Extramarital sex: is there an increased risk for HIV transmission? A study of male couples of mixed HIV status. AIDS Educ Prev.
19. Hays RB, Paul J, Ekstrand M, et al. Actual versus perceived HIV status, sexual behaviors and predictors of unprotected sex among young gay and bisexual men who identify as HIV-negative, HIV-positive and untested. AIDS.
20. Semple SJ, Patterson TL, Grant I. Partner type and sexual risk behavior among HIV positive gay and bisexual men: social cognitive correlates. AIDS Educ Prev.
21. de Vroome EMM, de Wit JBF, Stroebe W, et al. Sexual behavior and depression among HIV-positive gay men. AIDS Behav.
22. Grulich AE, Prestage GP, Kippax SC, et al. HIV serostatus of sexual partners of HIV-positive and HIV-negative homosexual men in Sydney. AIDS.
23. Hays RB, Kegeles SM, Coates TJ. Unprotected sex and risk taking among young gay men within boyfriend relationships. AIDS Educ Prev.
24. Marks G, Bingman CR, Duvas TS. Negative affect and unsafe sex in HIV-positive men. AIDS Behav.
25. Crepaz N, Marks G, Mansergh G, et al. Age-related risk for HIV infection in men who have sex with men: examination of behavioral, relationship, and serostatus variables. AIDS Educ Prev.
26. Crawford JM, Rodden P, Kippax S, et al. Negotiated safety and other agreements between men in relationships: risk practice defined. Int J STD AIDS.
27. Kippax S, Noble J, Prestage G, et al. Sexual negotiation in the AIDS era: negotiated safety revisited. AIDS.
28. Kalichman SC, Roffman RA, Picciano JF, et al. Sexual relationships, sexual behavior, and HIV infection: HIV-seropositive gay and bisexual men seeking prevention services. Prof Psychol Res Pr.
29. Mansergh G, Marks G, Colfax GN, et al. "Barebacking" in a diverse sample of men who have sex with men. AIDS.
30. Marks G, Ruiz MS, Richardson JL, et al. Anal intercourse and disclosure of HIV infection among seropositive gay and bisexual men. J Acquir Immune Defic Syndr Hum Retrovirol.
31. Sacco WP, Rickman RL. AIDS-relevant condom use by gay and bisexual men: the role of person variables and the interpersonal situation. AIDS Educ Prev.
32. Darrow WW, Webster RD, Kurtz SP, et al. Impact of HIV counseling and testing on HIV-infected men who have sex with men: the South Beach Health Survey. AIDS Behav.
33. Crepaz N, Marks G. Towards an understanding of sexual risk behavior in people living with HIV: a review of social, psychological, and medical findings. AIDS.
34. Vincke J, Bolton R, Miller M. Younger versus older gay men: risks, pleasures and dangers of anal sex. AIDS Care.
35. Waldo CR, Coates TJ. Multiple levels of analysis and intervention in HIV prevention science: exemplars and directions for new research. AIDS.
36. Derogatis LR. Brief Symptom Inventory: Administration, Scoring and Procedures Manual.
Minneapolis: National Computer Systems; 1993.
37. Liang KY, Zeger SL. Longitudinal data analysis using generalized linear models. Biometrics.
38. Derogatis LR, Melisaratos N. The Brief Symptom Inventory: an introductory report. Psychol Med.
39. Blazquez MV, Madueno JA, Jurado R, et al. Human herpesvirus-6 and the course of HIV infection. J Acquir Immune Defic Syndr Hum Retrovirol.
40. Fleming DT, Wasserheit JN. From epidemiological synergy to public health policy and practice: the contribution of other sexually transmitted diseases to sexual transmission of HIV infection. Sex Transm Infect.
41. Allen S, Tice J, Van de Peere P, et al. Effect of serotesting with counseling on condom use and seroconversion among HIV discordant couples in Africa. BMJ.
42. Padian NS, O'Brien TR, Chang YC, et al. Prevention of heterosexual transmission of HIV through couple counseling. J Acquir Immune Defic Syndr Hum Retrovirol.
Keywords:© 2005 Lippincott Williams & Wilkins, Inc.
homosexual men; sexual behaviors; risk factors; condoms; HIV