From 2006 to 2009 male-to-male sex was the largest HIV transmission category in the United States.1 During this time, the number of new HIV/AIDS diagnoses among men who have sex with men (MSM) in the United States overall increased 14%, with the largest percent increase (53%) among MSM between 13 and 24 years old.1 No other risk group had an increase in cases during the same period.
Examination of the continued increase in New York City (NYC) cases among MSM has suggested 2 different risk groups distinguished by age. Specifically, the proportion of cases among MSM 30 years of age or older is decreasing, whereas the proportion younger than 30 years has increased from 29% of all new diagnoses in MSM in 2001 to 47% in 2009.2,3 This age divergence is accompanied by a difference in racial composition: 77% of young MSM were black or Hispanic, whereas only 58% of older MSM were. These differences by age group are corroborated by recent trends in primary and secondary syphilis cases. Among males aged 15–24 years, syphilis cases have sharply increased in NYC and other US cities, compared with more modest increases among males older than 25 years.4
The reasons for the differing trajectories in numbers of newly identified HIV cases among younger and older MSM are not clear. A better understanding, however, is necessary to fashion appropriate prevention programs. Although surveillance data have been used to identify these trends, such data cannot provide additional detail relevant for prevention programming, such as reasons for HIV testing, sexual identity, sexually transmitted infection (STI) history, venues for meeting partners, characteristics of sex partners, and HIV disclosure practices.
To improve the characterization of HIV epidemics among younger and older MSM, we supplemented an analysis of citywide HIV surveillance data with an analysis of data from PS interviews with newly diagnosed MSM in NYC. In addition, we hypothesized that disassortative mixing by age among MSM might explain the increase in new diagnoses among young MSM because their sexual contact with older MSM would expose them to a higher HIV prevalence pool.
Data were analyzed from 2 sources: the NYC Department of Health and Mental Hygiene HIV Surveillance Registry (HARS) and Field Services Unit (FSU).
HARS is a population-based surveillance registry of all persons diagnosed with AIDS (since 1981) and/or HIV infection (since 2000) in NYC according to case definitions of the US Centers for Disease Control and Prevention (CDC)5,6 and is described in detail elsewhere.5,7 All HIV-related lab reports are matched to HARS; nonmatching reports that may represent a previously unreported case of HIV prompt a field investigation and medical record review to confirm case status and collect sociodemographic and risk data.
The NYC HIV PS Database contains data collected by NYC Department of Health and Mental Hygiene's HIV FSU, which was established in 2006 to assist providers and patients with PS for HIV-infected patients. FSU participating facilities were selected on the basis of their location in NYC neighborhoods with high HIV prevalence and mortality. During the period of this analysis, there were 10 FSU participating facilities. FSU staff actively sought in-person oral interviews with all persons newly diagnosed with HIV at participating facilities. FSU staff attempted to interview patients as soon after their diagnosis as possible. Interview data were collected on a standard form and were supplemented with information from the patient's medical record. Information on FSU-interviewed patients was stored in a central database, and FSU-interviewed patients were linked by a unique identifier to the matching case in HARS.
Our study included MSM living in NYC aged 13 years or older newly diagnosed with HIV infection between January 1, 2007 and December 31, 2008. We compared the FSU MSM population to MSM reported to HARS. HARS data were current as of September 30, 2009. The main analyses compared younger and older MSM interviewed by FSU for PS.
MSM were defined as patients whose sex at birth was male who reported ever having sex with other men, regardless of whether they named a male sex partner for HIV notification. MSM reporting a history of injection drug use were considered MSM for analytic purposes. Younger MSM (YMSM) were defined as MSM who were 13–29 years of age at HIV diagnosis, whereas older MSM were 30 years or older at HIV diagnosis.
We compared sociodemographic characteristics and risk behaviors among MSM younger than 30 years to determine the most appropriate age cutoff for the YMSM group (younger than 25 years old vs. younger than 30 years old) before proceeding to the additional analysis. We found that 25-year to 29-year olds were similar to the 20-year to 24-year olds and decided to use 30 years of age as the cutoff for the 2 groups to be compared in our analysis.
MSM reported age, race/ethnicity, country of birth, and sexual orientation.
MSM were asked to provide their reasons for seeking an HIV test when they were initially diagnosed with HIV infection and for the number of times they tested for HIV in the past 2 years.
HIV-Related Risk Behaviors
MSM were asked about the following behaviors or events during the 12 months preceding the interview: number of sex partners by current gender (male, female, and transgender), recreational drug use including injection drugs and sharing of needles, any STI diagnosis as reported by the interviewed MSM or documented in their medical chart, location or venue where they met their sex partners (eg, bars/clubs, parks, internet), and regularity of condom use (always, sometimes, or never).
Characteristics of Sexual Partners
For HIV partner notification, MSM were asked to name sex partners from the 2 years before interview. For these partners, demographic information, including age, gender, and race/ethnicity was collected and whether the patient disclosed his HIV status to named partners.
We compared sociodemographic characteristics of all MSM reported to HARS during this time to the subset interviewed by FSU for HIV PS. Within the FSU-based population, we characterized and compared patient demographics, HIV testing history, HIV-related risk behaviors and the characteristics of named sexual partners. The χ2 and Fisher exact tests were used to compare categorical variables. The T tests were used to compare the age differences between MSM and the sex partners they named for partner notification. Wilcoxon rank-sum tests were used to compare mean number of sex partners in the past 12 months, because the data were skewed, and to compare medians. SAS version 9.1.3 (SAS Institute Inc, Cary, NC) was used for statistical analyses.
Comparison of MSM Citywide and FSU Patients
From 2007 to 2008, 7965 persons were newly diagnosed with HIV infection in NYC, including 3292 MSM. Of these, 389 (9%) were referred to the FSU for PS. Compared with MSM citywide, FSU MSM were more likely to have been diagnosed with HIV at a younger age (median age in years: 27 vs. 32, P < 0.01) and to have been born outside of the United States (33% vs. 27%, P < 0.01) (Table 1).
MSM Patient Population—HIV PS Data
The FSU staff interviewed 336 MSM (86%) of the 389 referred. The median number of days between HIV diagnosis and interview was 25 for YMSM and 17 for older MSM. The median age at referral was 28 years. YMSM comprised 54% of all MSM. Most YMSM (95%) and older MSM (87%) reported either black or Hispanic race/ethnicity, however, more YMSM than older MSM were black (59% vs. 48%, P = 0.048). Nineteen blacks, who reported Hispanic ethnicity, were classified as Hispanic; of these, 11 were YMSM. YMSM were more likely to be US-born, to report their sexual identity as gay, and were less likely to report their sexual identity as heterosexual (5% vs. 21%, P < 0.01, excluding other or unknown identity) (Table 2). Although more older MSM were foreign-born, there were no differences in the rate of gay self-identification between US-born and non–US-born MSM (70% vs. 67%, P = 0.21).
YMSM reported more often than older MSM that they were routinely tested for HIV (17% vs. 7%, P < 0.01) and that the test leading to the incident diagnosis was done because they were making sure they were HIV negative (38% vs. 26%, P = 0.02). Significantly more YMSM than older MSM reported having tested for HIV at least once in the past 2 years (66% vs. 40%, P < 0.01).
HIV-Related Risk Behavior
YMSM reported slightly more sex partners overall and more male sex partners in the past 12 months. They were more likely to report having met a partner on the internet and a history of recent STI (Table 3). Seventy-five (22%) MSM did not report having a male sex partner in the past 12 months (20 YMSM and 55 older MSM). The 2 groups reported similar rates of condom use in the past 12 months (Table 3).
Drug use also varied. YMSM were less likely to have used noninjecting cocaine or methamphetamines in the past 12 months and less likely to have ever exchanged money or drugs for sex (Table 3). There were 10 (3%) MSM who ever injected drugs, 4 of whom were YMSM. Only 5 MSM reported injecting drugs in the past 12 months.
Characteristics of Patients' Sexual Partners
Significantly more YMSM named at least 1 male partner for HIV notification, whereas a higher percentage of older MSM named female sex partners (28% vs. 9%, P < 0.01). Fewer YMSM reported having disclosed their HIV-positive status to the male sex partners they named (Table 4).
We identified differences in age and race/ethnicity mixing between MSM and their male sex partners. More YMSM named partners whose age exceeded their own compared with older MSM (Table 4). Among the 48 younger partners of older MSM, 29% were between 5 and 10 years younger and 33% were more than 10 years younger. The median age difference between YMSM and their partners was +3 years (interquartile range: partners 0–8 years older than the YMSM naming them). The median age difference between older MSM and the partners they named was −2 years (interquartile range: 7 years younger to 5 years older) (Table 4).
Black MSM in both age groups named mainly black sex partners (74% of YMSM and 71% of older MSM). Although Hispanic YMSM less frequently named Hispanic sex partners (54% of YMSM and 59% of older MSM), Hispanic YMSM were more likely to name black partners than older Hispanic MSM (27% vs. 13%, P = 0.09) (Table 4).
Our analysis suggests that there are 2 demographic groups with distinct characteristics within the MSM HIV epidemic in NYC: YMSM and older MSM. The behavioral differences in these 2 age groups have important implications for HIV prevention planning. Overall, there is a concerning growth in the HIV epidemic among young MSM that coexists with a slow but steady decline in the epidemic among MSM 30 years or older.
Studies comparing younger and older MSMs' sexual risk behaviors report that YMSM use condoms less frequently,8 have more unprotected receptive anal sex,9 have a younger sexual debut,10 and continue risky sexual behaviors after HIV diagnosis.11 One study found that young MSM were diagnosed sooner after their acquisition of HIV than older MSM, but this association was no longer significant in the multivariate analysis.12 In another analysis about testing behavior, a higher proportion of younger MSM than older MSM tested HIV positive at the time of interview, but reported that the result of their most recent HIV antibody test was negative, indeterminate, or unknown, or that they had never been tested,13 suggesting that lack of awareness of HIV infection is more common among YMSM.
In our study, YMSM named more sex partners to the FSU than older MSM, which demonstrates the importance of providing HIV PS to MSM in this age group. This also suggests PS among YMSM is an efficient means of notifying partners of their exposure to HIV infection and of identifying previously undiagnosed HIV infection among partners of persons living with HIV. The fact that YMSM named more partners may reflect a greater willingness of YMSM to participate in PS interviews. In situations where resources for PS are limited, prioritizing YMSM for PS may be appropriate.
FSU YMSM were more likely to report gay sexual identity than were older FSU MSM, which is somewhat unexpected given published findings on differences in likelihood of disclosure of same-sex behavior to healthcare providers by age. In particular, 1 NYC study found that YMSM do not disclose their sexual orientation as frequently as older MSM to health care providers.14 Our findings suggest that YMSM may be more receptive to messages specifically targeted to a gay-identified audience then older MSM.
We identified important sexual risk behavior differences between YMSM and older MSM. YMSM reported being tested for HIV more frequently than older MSM. CDC recommends HIV testing of MSM at least annually.15 Among MSM in NYC, overall rates of having ever tested for HIV and testing for HIV in the last year are high and have been increasing.16 However, we found a large proportion (60%) of older MSM reported having not tested in the 2 years preceding their HIV diagnosis.
YMSM were more likely than older MSM to report an STI diagnosis in the last 12 months. The number of recent sex partners among this group of YMSM is lower than other studies.17,18 This may be due to a larger proportion of FSU YMSM being black since previous studies report black MSM have fewer partners compared with other MSM.19 In addition, in this analysis, MSM were reported from large medical facilities rather than recruited from gay venues.
As expected from this group of newly diagnosed MSM, less than one-fifth from either age group reported condom use in the past 12 months. We found that partners of YMSM tended to be older than the YMSM who named them, which was not surprising given published observations of the association of older sex partners and acquisition of HIV infection among YMSM.20,21 For YMSM, having sex partners with higher HIV prevalence (older partners) may be contributing to the rising HIV prevalence among this group. Most of the black FSU MSM reported black sex partners, consistent with published findings showing the likelihood of assortative mixing,22–24 however, a substantial proportion of Hispanic MSM described in this analysis reported partners of different race/ethnicities, particularly blacks. Thus, one can expect the 2 groups to have a similar HIV prevalence.
Factors underlying preferences for sex partners of an older age or specific race/ethnicity are complex and may be driven in part by the age distribution of MSM overall. For example, some YMSM may prefer older MSM as sex partners, whereas for other YMSM, their partnerships with older MSM may be driven primarily by the fact that the number of MSM more than 30 years of age exceeds that of YMSM, and therefore, potential partners are more likely to be older MSM.25
There are several limitations to our findings. Interviewed MSM may have provided what they believed were socially desirable answers to questions about their risk behaviors, including information on their sex partners (eg, underreporting recent sex partners while overreporting both the extent of HIV disclosure to sex partners and their condom use). Partners' age and race/ethnicity were not drawn from partners' self-report, as would be ideal, but rather from interviews with the MSM who named them. Therefore, findings related to differences in age and race/ethnicity between MSM and their partners are limited by the interviewed MSM's awareness and ability to recall this information. Furthermore, because a sexual relationship was the only inclusion criteria for the named partners in this analysis, other qualities of the relationship (eg, “main” vs. “casual” partner) between the 2 individuals could vary widely, and this variability may have affected the consistency and accuracy of partner information collected.
Our findings on HIV disclosure should be interpreted with caution because MSM were newly diagnosed at the time they named their sex partners and may not have had the opportunity to have disclosed their HIV status. Also, our findings may not be generalizable to all newly diagnosed MSM in NYC or elsewhere in the United States. FSU MSM comprised only 9% of all NYC MSM newly diagnosed during the analysis period. Furthermore, because FSU participating facilities were located in predominately black and Hispanic neighborhoods with high HIV prevalence and mortality, few (n = 20) white MSM were interviewed, limiting our ability to compare with whites. Finally, because NYC is a place where many MSM come specifically to reveal their sexual preference (ie, “come out”), our findings may not be representative of MSM in other jurisdictions.
Our study has identified important differences in HIV risk behaviors and sexual partnerships between YMSM and older MSM newly diagnosed with HIV. We found that YMSM were more willing to provide the names of male sex partners for the purposes of partner notification than were older MSM, suggesting that YMSM may be more willing to participate fully in PS activities. Based on these findings, we recommend more emphasis on targeting PS to YMSM as a possible way to increase the efficiency of identification of previously undiagnosed persons and facilitate timely linkage to care.
The authors are grateful to all the FSU staff for their hard work in interviewing HIV-infected patients for PS. We thank Dr. Wilson Lo for his work on earlier analyses of the article; Dr. Sarah Braunstein for helpful comments on earlier drafts of this article; and Dr. Kent Sepkowitz for his editorial guidance.
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