Abstract
Background:
International travel poses potential challenges to HIV prevention. A number of studies have observed an association between travel and behavioral disinhibition. In the present study, we assessed differences in sexual behavior while traveling internationally and within the United States compared to being in the home environment.
Methods:
A probability-based sample of men who have sex with men (MSM) from the San Francisco Bay Area who had traveled internationally in the previous 12 months was recruited through an adapted respondent-driven sampling methodology (N=501). Participants completed interviewer-administered, computer-assisted surveys.
Results:
Detailed partner-by-partner behavioral data by destination type were collected on 2,925 sexual partnerships: 1,028 while traveling internationally, 665 while traveling within the United States and 1,232 while staying in the San Francisco Bay Area. The proportion of partnerships during international travel that involved unprotected anal intercourse (UAI) was lower compared to during domestic travel and staying locally. International travel was associated with decreased odds of receptive UAI (AOR=0.65, p=0.02) compared to staying locally and there was a trend towards decreased odds of insertive UAI (AOR=0.70, p=0.07).
Conclusions:
MSM engaged in proportionately fewer sexual activities which present a high HIV transmission risk when traveling internationally, namely unprotected receptive and insertive anal intercourse and particularly with HIV serodiscordant partners. The lower sexual risk-taking during international travel was robust to controlling for many factors, including self-reported HIV serostatus, age, relationship status and type of partnership. These findings suggest that when traveling internationally, MSM may experience behavioral disinhibition to a lesser extent than had been described previously.
INTRODUCTION
International travel poses potential challenges to HIV prevention. Documentation of the contribution of travel to the spread of HIV has been based upon global tracking of HIV strains.[1-5] Sexual networks that extend across international borders are commonplace as geographic boundaries become less restrictive with the increasing ease of intercontinental travel.[6]
A number of studies have observed an association between travel and behavioral disinhibition in a number of different populations, including young adults and men who have sex with men (MSM).[7-13] Behavioral disinhibition, manifesting as increases in risk behavior, may stem from the fact that travel provides a respite from the daily routines of work and home life and potentially removes the social constraints for practicing safer sex. International travel also presents a change in environment that may lead some MSM to engage in sexual behaviors that have a high risk for HIV transmission.[10-13] Taken together, these factors may create situations that may result in increased HIV transmission risk when traveling.
Gay and bisexual men who reside in the Greater San Francisco Area frequently travel internationally. More than a quarter of respondents of a recent National HIV Behavioral Surveillance survey conducted in the San Francisco Bay Area reported international travel in the previous year.[14] Among a cohort of MSM with newly-diagnosed HIV infection, 55% of participants had lived or traveled outside of the United States during the time period when they may have acquired and potentially further transmitted their infection.[15]
In the present study, “International Travel Research to Inform Prevention” (I-TRIP), we explored differences in sexual risk behavior while traveling internationally and to destinations within the United States compared to being in the home environment among a population-based sample of MSM.
METHODS
MSM from the San Francisco Bay Area were recruited using respondent-driven sampling (RDS) from April 2009 through June 2011. MSM were eligible for participation in the study if they were 18 years or older, residents of ten San Francisco Bay Area counties, self-identified as male and had traveled internationally in the previous 12 months. RDS is a methodology used for the recruitment of hard-to-reach populations that uses long-chain referral whereby members of the target population recruit other members.[16-18]
For this study, we developed innovative adaptations to conventional RDS for the recruitment of participants. The methodological innovations included offering participants a choice between electronic and paper coupons for recruitment referrals and modifying the secondary incentives structure from small cash amounts to raffle entries for periodic large cash prize raffle drawings. The I-TRIP study participant recruitment process and RDS adaptations have been described in detail in a prior publication.[19]
Participants completed interviewer-administered, computer-assisted surveys. Demographic characteristics collected included age, race/ethnicity, highest education level, employment status, sexual orientation and relationship status. Classification of participants’ HIV serostatus for this analysis was based on self-report as it represented their perception of their serostatus when recalling past risk behaviors. Participants were offered HIV testing upon completion of the survey following the standard testing procedures of the San Francisco Department of Public Health. The study received approval from the Institutional Review Board at the University of California, San Francisco.
Sexual activity in the previous 12 months was evaluated in two ways. First, aggregate information was obtained on the total numbers of partners and sexual behaviors that took place within the previous 12 months while traveling internationally, traveling domestically and staying locally. In order to capture more refined contextual information, a detailed assessment of a select number of partnerships was conducted. Partnership-level data were collected for up to three of the most recent sexual partnerships per international country, for up to two of the most recently visited countries, i.e., a maximum of six international sexual partnerships; up to three of the most recent sexual partnerships during domestic travel; and up to three of the most recent sexual partnerships while staying locally. For analysis purposes, a partnership refers to a unique individual in each geographic location. Data collected include the number, gender and HIV serostatus of sexual partners, partnership type (main, casual or anonymous) and types of sexual behavior. The primary outcomes of interest within the partnerships were insertive and receptive unprotected anal intercourse (UAI). Main partnerships were defined as those with individuals whom the participant had a commitment, e.g., spouse, domestic partner or boyfriend. Casual partnerships were defined as those involving individuals with whom the participant did not have a commitment or whom the participant did not know well. Anonymous partnerships were with individuals with whom the participant had sex once and did not know how to contact again. Partnerships were classified as HIV serodiscordant in cases where the participants and their sexual partner were of the opposite serostatus and where the participants’ HIV serostatus or that of their partner was unknown.[20]
Frequency distributions were calculated for categorical variables; mean and standard deviation (SD), and median and inter-quartile range (IQR) were calculated for continuous variables. Generalized estimating equations (GEE) with the binomial model and logistic link were used to estimate bivariate and multivariate odds ratios for the sexual behavior outcomes of interest and all chi-square tests involving sexual behaviors reported in the results. GEE models were clustered at the participant level. Use of GEE produced population-averaged models that fit generalized linear models while also adjusting the estimated standard errors for the effects of clustering as a result of multiple observations per participant. Covariates at the participant-, partnership- and trip-level hypothesized a priori to be associated with the main outcomes of interest (insertive UAI, receptive UAI) were included in the multivariate models. RDS weights were created using RDSAT based on participant age and race to account for the sampling design. Univariate estimates and multivariate GEE models were RDS-weighted.
RESULTS
A total of 501 participants were enrolled in the I-TRIP study. Seventy seeds were recruited, of which 41 provided at least one successfully enrolled referral. Recruitment chains ranged from 2 generations (seed and one wave of referrals) up to 13 generations (seed and 12 waves of referrals), with a median of four wave generations. Equilibrium was reached by the 5th wave generation for all demographic characteristics, including age, race/ethnicity, sexual orientation and education level. Homophily was assessed on a scale of -1 (participant recruited only from outside his group) to 1 (participant recruited only from inside his group). Values at either extreme of the homophily scale were rarely observed among the variables of age, race, sexual identity, education level, county of residence and HIV status.
Participants’ demographic characteristics and sexual behaviors are summarized in Table 1. The median age was 40 years old (IQR 31-48). The majority were white, self-identified as homosexual or gay, had a college degree or higher, were employed full- or part-time, single and HIV-negative. Self-reported HIV status was highly correlated with laboratory results. Among participants self-reporting as HIV-negative, concordance was 99% as there were 2 positive and 1 undetermined test results. Among participants self-reporting as HIV-positive, concordance was 98% as there were 1 negative and 1 undetermined test results. Three of the 14 participants who self-reported their HIV serostatus as unknown (indeterminate or never tested) or who refused to respond were HIV-positive by laboratory testing. The majority of participants reported engaging in UAI in the previous 12 months.
Table 1:
Demographic characteristics, self-reported HIV serostatus and sexual behaviors in the previous 12 months of men who have sex with men who travel internationally, San Francisco Bay Area, 2009-2011 (N=501 participants)
| N | Crude % | Weighted % (95% CI) | |
|---|---|---|---|
| Characteristics | |||
| Age Group (in years) | |||
| 18-25 | 38 | 7.6 | 11.2 (5.0-17.0) |
| 26-30 | 85 | 17.0 | 16.3 (11.1-23.8) |
| 31-35 | 62 | 12.4 | 10.7 (5.9-15.5) |
| 36-40 | 71 | 14.2 | 13.9 (9.5-20.3) |
| 41-45 | 83 | 16.6 | 14.8 (9.0-18.2) |
| 46-50 | 52 | 10.4 | 11.4 (6.4-15.9) |
| 51-55 | 49 | 9.8 | 9.2 (5.8-14.2) |
| 56-60 | 36 | 7.2 | 7.1 (4.3-13.8) |
| >60 | 25 | 5.0 | 5.3 (2.3-9.3) |
| Race | |||
| White | 389 | 77.6 | 70.8 (62.5-79.2) |
| Asian | 77 | 15.4 | 21.0 (13.4-29.6) |
| Black | 12 | 2.4 | 2.7 (0.6-5.9) |
| Mixed/Other | 23 | 4.6 | 5.5 (2.0-9.0) |
| Ethnicity | |||
| Not Hispanic | 433 | 86.4 | 84.0 (78.6-88.9) |
| Hispanic | 68 | 13.6 | 16.0 (11.1-21.4) |
| Education | |||
| High school/GED | 18 | 3.6 | 5.2 (2.1-8.7) |
| Some college | 65 | 13.0 | 18.4 (13.1-26.5) |
| College degree | 234 | 46.7 | 43.8 (36.7-50.3) |
| Graduate school | 184 | 36.7 | 32.6 (25.2-38.9) |
| Sexual Orientation | |||
| Homosexual/Gay | 479 | 95.6 | 92.1 (84.6-96.3) |
| Bisexual | 19 | 3.8 | 7.0 (2.8-14.4) |
| Heterosexual/Straight/Other | 3 | 0.6 | 0.9 (0.0-2.3) |
| Relationship Status | |||
| Single | 261 | 52.1 | 59.5 (49.8-66.3) |
| Committed relationship | 125 | 25.0 | 20.8 (14.1-26.9) |
| Domestic partnership/Civil union/Marriage | 107 | 21.4 | 18.1 (13.8-27.5) |
| Other | 8 | 1.6 | 1.6 (0.3-2.5) |
| Employment Status | |||
| Full time | 305 | 60.9 | 61.6 (52.4-67.9) |
| Part time | 70 | 14.0 | 14.5 (10.1-20.5) |
| Working intermittently | 34 | 6.8 | 4.0 (2.3-6.1) |
| Not working | 35 | 7.0 | 9.2 (5.1-14.3) |
| Retired | 22 | 4.4 | 4.3 (1.6-8.8) |
| Something else | 35 | 7.0 | 6.4 (3.4-9.6) |
| HIV Status (self-reported) | |||
| HIV negative | 362 | 72.3 | 68.3 (58.1-75.2) |
| HIV positive | 125 | 25.0 | 27.7 (20.9-38.1) |
| Indeterminate | 7 | 1.4 | 1.0 (0.4-2.3) |
| Never tested | 5 | 1.0 | 2.8 (0.2-5.9) |
| Refused | 2 | 0.4 | 0.1 (0.0-0.6) |
| Sexual behaviors with up to 3 of the most recent male sexual partners in up to 4 locations (3 destination types) in the previous 12 months | |||
| Any Anal intercourse | |||
| Yes | 430 | 85.8 | 84.4 (77.2-89.5) |
| Any Unprotected Anal Intercourse (UAI) | |||
| Yes | 316 | 63.1 | 58.4 (51.5-67.4) |
| Any Receptive UAI | |||
| Yes | 251 | 50.1 | 48.3 (42.1-57.1) |
| Any Insertive UAI | |||
| Yes | 250 | 49.9 | 44.3 (37.8-53.0) |
Participants reported visiting a mean of 3.0 countries (SD 2.8) in the previous 12 months and a median of 2 countries (IQR 1-4). The most frequently visited countries were Mexico, Canada and the United Kingdom. Participants took a mean of 6.3 trips (SD 9.6) within the United States in the past 12 months and a median of 4 trips (IQR 2-6).
The partnership assessment tool collected detailed behavioral data on a total of 2,925 male sexual partnerships: 1,028 while traveling internationally, 665 while traveling domestically and 1,232 while staying locally in the San Francisco Bay Area. When compared to the overall number of partnerships reported in the previous 12 months, this assessment tool captured detailed partnership-level data on all partnerships while traveling internationally for 387 participants (77.3%), while traveling domestically for 394 participants (78.6%) and while staying locally for 182 participants (36.3%).
The median number of male sexual partnerships across all destination types was 10 (IQR 5-21), with a median of 2 (IQR 1-4) while traveling internationally, 1 (IQR 0-3) while traveling domestically and 5 (IQR 2-14) while staying locally. Participants reported a median of 4 partnerships (IQR 2-10) across all destination types in which there was any anal intercourse; the median was 1 (IQR 0-2) while traveling internationally, 1 (IQR 0-1) while traveling domestically and 2 (IQR 1-6) while staying locally. For unprotected anal intercourse, participants reported a median of 1 partnership (IQR 0-4) across all destination types; the median was 0 (IQR 0-1) while traveling internationally, 0 (IQR 0-1) while traveling domestically and 1 (IQR 1-4) while staying locally.
Participants reported a total of 25 sexual partnerships with women, of which 10 partnerships were while traveling internationally, 8 while traveling domestically and 7 while staying locally. There were 2 partnerships with transgender individuals reported, both of which occurred during international travel. Given the relatively few partnerships with women and transgender individuals, subsequent analyses focused on partnerships with men.
Participants provided detailed behavioral data on 1,016 male sexual partnerships while traveling internationally, 657 male partnerships while traveling domestically and 1,225 male partnerships while staying locally. Table 2 summarizes the different types of sexual behaviors with male partners by destination type and HIV seroconcordancy. Oral intercourse was the most common sexual activity reported across all destination types, followed by mutual masturbation and AI. Participants reported proportionately fewer partnerships that involved oral intercourse, oral-anal contact and all forms of anal intercourse while traveling internationally compared to while staying in the San Francisco Bay Area. They also engaged in proportionately less receptive UAI within serodiscordant partnerships. The proportion of international travel partnerships that involved UAI (24.9%) was lower compared to domestic travel (27.1%) and local partnerships (33.1%). The proportion of AI that was unprotected was significantly higher (χ2=25.39; p< 0.01) when staying locally (55.3%) compared to traveling internationally (45.5%) and domestically (46.2%); there was no significant difference in UAI between traveling domestically and internationally (p=0.26).
Table 2:
Sexual behaviors with up to 3 of the most recent male partnerships in up to 4 locations (3 destination types) in the previous 12 months, by destination type and partnership HIV seroconcordancy, of men who have sex with men who travel internationally, San Francisco Bay Area, 2009-2011 (N=501 respondents for 2,898 partnerships)
| Destination Type | |||||
|---|---|---|---|---|---|
| San Francisco Bay Area N (%)* |
United States N (%)* |
International N (%)* |
χ2 ** | p-value** | |
| Total Partnerships | |||||
| Overall | 1,225 (100) | 657 (100) | 1,016 (100) | -- | -- |
| Seroconcordant | 801 (100) | 420 (100) | 532 (100) | -- | -- |
| Serodiscordant | 424 (100) | 237 (100) | 484 (100) | -- | -- |
| Mutual Masturbation | |||||
| Overall | 962 (78.7) | 504 (76.7) | 776 (76.4) | 1.49 | 0.47 |
| Seroconcordant | 664 (82.9) | 329 (78.3) | 420 (79.0) | 9.52 | <0.01 |
| Serodiscordant | 298 (70.6) | 175 (73.8) | 356 (73.6) | 4.22 | 0.12 |
| Oral Intercourse | |||||
| Overall | 1,109 (90.7) | 589 (89.7) | 906 (89.2) | 4.21 | 0.12 |
| Seroconcordant | 738 (92.1) | 396 (94.3) | 493 (92.7) | 1.27 | 0.53 |
| Serodiscordant | 371 (87.9) | 193 (81.4) | 413 (85.3) | 5.29 | 0.07 |
| Oral-Anal Contact | |||||
| Overall | 523 (42.8) | 278 (42.3) | 357 (35.1) | 20.81 | <0.01 |
| Seroconcordant | 409 (51.1) | 207 (49.3) | 227 (42.7) | 18.36 | <0.01 |
| Serodiscordant | 114 (27.0) | 71 (30.0) | 130 (26.9) | 0.24 | 0.89 |
| Any Anal Intercourse | |||||
| Overall | 733 (59.8) | 386 (58.8) | 557 (54.8) | 10.30 | <0.01 |
| Seroconcordant | 544 (67.9) | 278 (66.2) | 340 (63.9) | 7.38 | 0.03 |
| Serodiscordant | 189 (44.6) | 108 (45.6) | 217 (44.8) | 1.30 | 0.52 |
| Insertive Anal Intercourse | |||||
| Overall | 511 (41.8) | 265 (40.3) | 385 (37.9) | 7.90 | 0.02 |
| Seroconcordant | 389 (48.6) | 193 (46.0) | 239 (44.9) | 8.39 | 0.02 |
| Serodiscordant | 122 (28.9) | 72 (30.4) | 146 (30.2) | 0.92 | 0.63 |
| Receptive Anal Intercourse | |||||
| Overall | 476 (38.9) | 220 (33.5) | 332 (32.7) | 16.9 | <0.01 |
| Seroconcordant | 358 (44.7) | 162 (38.6) | 205 (38.5) | 10.25 | <0.01 |
| Serodiscordant | 118 (28.0) | 58 (24.5) | 127 (26.2) | 4.14 | 0.13 |
| Any Unprotected Anal Intercourse (UAI) | |||||
| Overall | 406 (33.1) | 178 (27.1) | 253 (24.9) | 27.92 | <0.01 |
| Seroconcordant | 332 (41.5) | 150 (35.7) | 181 (34.0) | 19.39 | <0.01 |
| Serodiscordant | 74 (17.5) | 28 (11.8) | 72 (14.9) | 4.85 | 0.09 |
| Insertive UAI | |||||
| Overall | 291 (24.0) | 132 (20.3) | 170 (16.9) | 23.92 | <0.01 |
| Seroconcordant | 249 (31.4) | 116 (27.6) | 128 (24.1) | 19.20 | <0.01 |
| Serodiscordant | 42 (10.1) | 16 (6.9) | 42 (8.8) | 3.52 | 0.17 |
| Receptive UAI | |||||
| Overall | 284 (23.3) | 104 (15.9) | 157 (15.5) | 36.00 | <0.01 |
| Seroconcordant | 233 (29.2) | 87 (20.8) | 113 (21.4) | 23.05 | <0.01 |
| Serodiscordant | 51 (12.1) | 17 (7.2) | 44 (9.1) | 6.70 | 0.04 |
Percentages in table do not sum to 100%; percentages represent “yes” responses only
Wald χ2 and p-value are from bivariate GEE models, adjusted for multiple observations per participant
Adjusted odds ratios (AOR) for sexual behavior outcomes using multivariate GEE modeling are presented in Table 3. Partner type (casual or anonymous vs. main) and HIV seroconcordancy (discordant or unknown vs. concordant) were significantly associated with a lower likelihood of partnerships in which the participant engaged in insertive UAI and receptive UAI. Participants whose self-reported serostatus was HIV-positive, unknown or refused to answer were more likely to report partnerships in which they engaged in insertive UAI and receptive UAI compared to HIV-negative participants. Older age was associated with a lower likelihood of partnerships in which the participant engaged in receptive UAI. Hispanic participants were more likely to report partnerships in which they engaged in insertive UAI. Insertive UAI and receptive UAI were not associated with race or relationship status. International travel and domestic travel were significantly associated with a lower likelihood of partnerships in which the participant engaged in receptive UAI compared to staying locally. There was a borderline significant association between international travel and a lower likelihood of partnerships in which the participant engaged in insertive UAI.
Table 3:
Adjusted odds ratios (AOR) and 95% confidence intervals (CI), RDS-weight, for sexual behavior outcomes with up to 3 of the most recent male sexual partnerships in up to 4 locations (3 destination types) in the previous 12 months, of men who have sex with men who travel internationally, San Francisco Bay Area, 2009-2011 (N=501 participants)
| Insertive UAI | Receptive UAI | |||||
|---|---|---|---|---|---|---|
| AOR | 95% CI | p-value | AOR | 95% CI | p-value | |
| Participant Age (years) | 0.98 | (0.96, 1.00) | 0.09 | 0.97 | (0.95, 0.99) | 0.01 |
| Participant Race | ||||||
| White | 1.00 | 1.00 | ||||
| Asian | 1.26 | (0.59, 2.70) | 0.55 | 1.47 | (0.85, 2.54) | 0.17 |
| Black | 0.73 | (0.11, 4.82) | 0.74 | 0.37 | (0.06, 2.20) | 0.28 |
| Mixed/Other | 1.52 | (0.78, 2.96) | 0.22 | 0.94 | (0.27, 3.35) | 0.93 |
| Participant Ethnicity | ||||||
| Not Hispanic | 1.00 | 1.00 | ||||
| Hispanic | 2.56 | (1.51, 4.36) | <0.01 | 0.97 | (0.52, 1.84) | 0.93 |
| Participant Relationship Status | ||||||
| Single | 1.00 | 1.00 | ||||
| Committed Relationship | 1.09 | (0.61, 1.94) | 0.77 | 1.42 | (0.86, 2.33) | 0.17 |
| Domestic Partnership/Civil Union/Marriage | 1.57 | (0.84, 2.93) | 0.16 | 1.71 | (0.98, 2.97) | 0.06 |
| Other | 0.56 | (0.21, 1.48) | 0.24 | 0.70 | (0.38, 1.30) | 0.26 |
| Participant HIV Status (self-reported) | ||||||
| HIV-Negative | 1.00 | 1.00 | ||||
| HIV-Positive | 3.04 | (1.64, 5.63) | <0.01 | 6.14 | (3.53, 10.69) | <0.01 |
| Unknown/Refused to Answer | 5.77 | (1.43, 23.31) | 0.01 | 12.97 | (4.06, 41.38) | <0.01 |
| Partner Type | ||||||
| Main Partner | 1.00 | 1.00 | ||||
| Casual Partner | 0.22 | (0.14, 0.33) | <0.01 | 0.21 | (0.13, 0.33) | <0.01 |
| Anonymous Partner | 0.15 | (0.08, 0.26) | <0.01 | 0.10 | (0.05, 0.20) | <0.01 |
| HIV Seroconcordancy with Partner | ||||||
| Concordant | 1.00 | 1.00 | ||||
| Discordant/Unknown | 0.17 | (0.08, 0.37) | <0.01 | 0.25 | (0.15, 0.40) | <0.01 |
| Destination Type | ||||||
| San Francisco Bay Area | 1.00 | 1.00 | ||||
| United States | 0.79 | (0.60, 1.05) | 0.11 | 0.58 | (0.40, 0.84) | <0.01 |
| International | 0.70 | (0.48, 1.03) | 0.07 | 0.65 | (0.46, 0.93) | 0.02 |
DISCUSSION
MSM engaged in proportionately fewer sexual activities that present a high HIV transmission risk when traveling internationally, namely unprotected receptive and insertive anal intercourse and particularly with HIV serodiscordant partners. Nearly half of sexual partnerships that took place while traveling internationally did not involve anal intercourse; when anal intercourse occurred, they were more likely to be protected. The lower risk during international travel was robust to controlling for many factors, including self-reported HIV serostatus, age, relationship status and type of partnership. These findings suggest that when traveling internationally, MSM may experience behavioral disinhibition to a lesser extent than had been described previously.[10-13]
Oral intercourse was reported in nearly all sexual partnerships, irrespective of destination type or participant HIV serostatus. A quarter of the sexual partnerships involved only oral intercourse and mutual masturbation, without any anal intercourse. This proportion increased to approximately half among serodiscordant partnerships, which may reflect an attempt to engage in lower-risk sexual activities to reduce the risk of HIV transmission. The observation that riskier sexual behaviors occurred more often with HIV seroconcordant partners may represent seroadapation.[21, 22]
Contrary to the hypothesis of dishinhibition while traveling, the I-TRIP study participants reported engaging in higher risk sexual behaviors with San Francisco Bay Area partnerships compared to international partnerships. One-third of participants reported having unprotected anal intercourse while staying locally, a prevalence that was comparable to the 31% reported by a study of sexual behaviors among MSM in San Francisco.[20] The level of unprotected anal intercourse reported by participants poses a risk for transmission of HIV and other sexually transmitted infections.
While participants may have been more likely to engage in unprotected anal intercourse because they felt more familiar with their local partners and/or knew their partner’s serostatus, the high prevalence of HIV in the San Francisco Bay Area belies any relative safety perceived. Moreover, the association between UAI and local partnerships remained significant even after adjusting for participants’ knowledge of their partners’ serodiscordancy and for partnership type in the multivariate model. The finding of why participants engaged in more sexual risk-taking with local casual and anonymous partners merits further examination, as there may be situational or cultural factors that influence local and international partnerships differently.
Under-reporting of higher risk sexual behavior is a potential limitation of this study. The fact that the survey was interviewer-administered may have introduced social desirability bias. The extent to which respondents may differentially under-report risk behavior by destination type is unknown. Another potential limitation is the fact that the partnership assessment algorithm did not capture all sexual partnerships that participants had in the 12 months prior to their enrollment in the study. However, detailed behavioral data was available for more than three-quarters of all sexual partnerships that took place while traveling internationally and domestically during this time frame. The data were not as comprehensive for local partnerships, which is understandable given that participants most likely spent the majority of the previous 12 months in the San Francisco Bay Area and therefore potentially had more local partnerships than the partnership assessment tool was designed to capture. However, since querying participants about specific behaviors with all partners over the entire 12 month time frame could introduce recall bias, we chose to ask only about the most recent partners at each destination type in order to minimize errors in recall. Nonetheless, we still found significantly higher levels of UAI within local partnerships, even after adjusting for partner type and HIV seroconcordancy.
We believe that the study was able to recruit a representative sample of the population of gay and bisexual men from the San Francisco Bay Area using our modified RDS methodology. We are not aware of any other population-based data on MSM living in the San Francisco Bay Area who travel internationally against which to compare our study sample. The eligibility criteria of recent international travel likely resulted in the recruitment of a larger proportion of participants of higher socioeconomic status. Population estimates of MSM stratified by race/ethnicity were unavailable for comparison with the demographic characteristics of study participants. However, MSM sub-population sizes can be projected using the total number of MSM from consensus estimates and census data.[23] These projections suggest that with approximately one-fifth of study participants being of Asian/Pacific-Islander descent and one-sixth of participants being of Hispanic/Latino descent, we were successful in recruiting a racially and ethnically diverse sample of participants. Approximately one-quarter of the study participants were HIV-positive, a proportion that is very similar to the 2011 HIV Consensus Estimates which are synthesized using recent available data from multiple sources.[24] The demographic characteristics of our HIV-positive participants were also similar to HIV surveillance data with regards to age, race and ethnicity.[24]
In summary, the I-TRIP study data suggest that MSM may refrain from risky sexual activity during international travel. The results from our large, probability-based sample of internationally traveling MSM using partner-by-partner information and destination type stand in contrast to the higher risk surmised in other studies.[10-13] Recent reports indicate global HIV epidemics in MSM continue to expand.[25, 26] While our findings are encouraging from the perspective of resurging transmission of HIV among MSM observed in many parts of the world, a better understanding of the causal factors that result in this risk differential is needed to promote risk reduction among MSM locally and internationally.
KEY MESSAGES.
MSM engaged in proportionately fewer sexual activities that present a high HIV transmission risk when traveling internationally, namely unprotected receptive and insertive anal intercourse.
Nearly half of sexual partnerships while traveling internationally did not involve anal intercourse; when anal intercourse occurred, they were more likely to be protected.
These findings suggest that when traveling internationally, MSM may experience behavioral disinhibition to a lesser extent than had been described previously.
FUNDING
This work was supported by the National Institute of Mental Health (NIH R01 MH080657, PI: Hong-Ha M. Truong).
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