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Biomedical subjects

M H Katz

Publications and source records attributed to M H Katz.

At least 19 recordsLinked to original sources
PubMed2006

Increases in sexually transmitted infections and sexual risk behaviour without a concurrent increase in HIV incidence among men who have sex with men in San Francisco: a suggestion of HIV serosorting?

BACKGROUND: Sexually transmitted infections (STI) and unprotected anal intercourse (UAI) have been increasing among men who have sex with men (MSM) in San Francisco. However, HIV incidence has stabilised. OBJECTIVES: To describe recent trends in sexual risk behaviour, STI, and HIV incidence among MSM in San Francisco and to assess whether increases in HIV serosorting (that is, selective unprotected sex with partners of the same HIV status) may contribute to preventing further expansion of the epidemic. METHODS: The study applies an ecological approach and follows the principles of second generation HIV surveillance. Temporal trends in biological and behavioural measures among MSM were assessed using multiple pre-existing DATA SOURCES: STI case reporting, prevention outreach programmatic data, and voluntary HIV counselling and testing data. RESULTS: Reported STI cases among MSM rose from 1998 through 2004, although the rate of increase slowed between 2002 and 2004. Rectal gonorrhoea cases increased from 157 to 389 while early syphilis increased from nine to 492. UAI increased overall from 1998 to 2004 (p<0.001) in community based surveys; however, UAI with partners of unknown HIV serostatus decreased overall (p<0.001) among HIV negative MSM, and among HIV positive MSM it declined from 30.7% in 2001 to a low of 21.0% in 2004 (p<0.001). Any UAI, receptive UAI, and insertive UAI with a known HIV positive partner decreased overall from 1998 to 2004 (p<0.001) among MSM seeking anonymous HIV testing and at the STI clinic testing programme. HIV incidence using the serological testing algorithm for recent HIV seroconversion (STARHS) peaked in 1999 at 4.1% at the anonymous testing sites and 4.8% at the STI clinic voluntary testing programme, with rates levelling off through 2004. CONCLUSIONS: HIV incidence among MSM appears to have stabilised at a plateau following several years of resurgence. Increases in the selection of sexual partners of concordant HIV serostatus may be contributing to the stabilisation of the epidemic. However, current incidence rates of STI and HIV remain high. Moreover, a strategy of risk reduction by HIV serosorting can be severely limited by imperfect knowledge of one's own and one's partners' serostatus.

Adult↗
PubMed2002

Volatile anaesthetics may be the main cause of early but not delayed postoperative vomiting: a randomized controlled trial of factorial design.

BACKGROUND: Despite intensive research, the main causes of postoperative nausea and vomiting (PONV) remain unclear. We sought to quantify the relative importance of operative, anaesthetic and patient-specific risk factors to the development of PONV. METHODS: We conducted a randomized controlled trial of 1180 children and adults at high risk for PONV scheduled for elective surgery. Using a five-way factorial design, we randomly assigned subjects by gender who were undergoing specific operative procedures, to receive various combinations of anaesthetics, opioids, and prophylactic antiemetics. RESULTS: Of the 1180 patients, 355 (30.1% 95% CI (27.5-32.7%)) had at least one episode of postoperative vomiting (PV) within 24 h post-anaesthesia. In the early postoperative period (0-2 h), the leading risk factor for vomiting was the use of volatile anaesthetics, with similar odds ratios (OR (95% CI)) being found for isoflurane (19.8 (7.7-51.2)), enflurane (16.1 (6.2-41.8)) and sevoflurane (14.5 (5.6-37.4)). A dose-response relationship was present for the use of volatile anaesthetics. In contrast, no dose response existed for propofol anaesthesia. In the delayed postoperative period (2-24 h), the main predictors were being a child (5.7 (3.0-10.9)), PONV in the early period (3.4 (2.4-4.7)) and the use of postoperative opioids (2.5 (1.7-3.7)). The influence of the antiemetics was considerably smaller and did not interact with anaesthetic or surgical variables. CONCLUSION: Volatile anaesthetics were the leading cause of early postoperative vomiting. The pro-emetic effect was larger than other risk factors. In patients at high risk for PONV, it would therefore make better sense to avoid inhalational anaesthesia rather than simply to add an antiemetic, which may still be needed to prevent or treat delayed vomiting.

Adolescent↗
PubMed2001

Postexposure prophylaxis for human immunodeficiency virus infection after sexual or injection drug use exposure: identification and characterization of the source of exposure.

In a nonrandomized study of nonoccupational postexposure prophylaxis (PEP), a cross-sectional evaluation of subjects who were the source of human immunodeficiency (HIV) exposure was performed to characterize partners of index subjects seeking nonoccupational PEP against HIV. Among 401 index subjects, 64 (16%) recruited a source subject. Those in a steady relationship and those who knew that the source subject was HIV antibody positive were more likely to recruit their source subject. Source subjects reported high rates of past (78%) and current (69%) antiretroviral use; 46% of those using antiretroviral drugs had detectable plasma HIV-1 RNA levels. Antiretroviral resistance was detected in many source subjects who reported any use of antiretrovirals and was rare among source subjects who reported no history of antiretroviral use. Clinicians often make treatment decisions on the basis of incomplete knowledge of the source subject's HIV status or antiretroviral treatment history. The treatment history, particularly nonuse of a class of antiretroviral drugs, can be used to predict drug resistance.

Adult↗
PubMed2001

Predictors of use of highly active antiretroviral therapy (HAART) among persons with AIDS in San Francisco, 1996-1999.

Highly active antiretroviral therapy (HAART) has contributed to a decrease in AIDS-related morbidity and mortality. This study used population-based AIDS surveillance data to evaluate the prevalence and predictors of HAART use among persons with AIDS in San Francisco. Use of HAART among persons living with AIDS increased from 41% in 1996 to 72% in 1999. Fourteen percent of persons diagnosed with AIDS between 1996 and 1999 initiated HAART before their AIDS diagnosis. Use of HAART before an AIDS diagnosis increased from 5% in 1996 to 26% in 1999. In the multivariable analysis, African Americans, injection drug users, and those without insurance at the time of AIDS diagnosis were less likely to use HAART before AIDS diagnosis. Delayed initiation of HAART after AIDS was more likely to occur among African Americans, injection drug users, homeless persons, those with public insurance, and those with higher CD4 counts. Although the overall prevalence of HAART use was high, disparity in use of HAART existed by race and risk group, patient's insurance status, and facility of diagnosis. Barriers in use of treatment should be identified so all persons with AIDS can benefit from improved therapies.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Incidence of human immunodeficiency virus among male-to-female transgendered persons in San Francisco.

OBJECTIVE: To estimate HIV incidence among male-to-female transgendered persons (MtF transgendered persons) who repeatedly tested for HIV antibodies at public San Francisco counseling and testing sites between July 1997 and June 2000. METHODS: HIV seroconversions were identified and person-time of observation were estimated using the date and result of the current test and the self-reported date and result of the previous test. Factors independently associated with HIV seroconversion were determined using multivariable proportional hazard analysis. RESULTS: HIV incidence was 7.8 per 100 person-years (95% confidence intervals [CI], 4.6-12.3) based on 13 seroconversions among 155 repeat testers with 167.7 person-years of observation. African-American race/ethnicity (adjusted relative hazard ratio [HR], 5.0; 95% CI, 1.5-16.2) and unprotected receptive anal intercourse (HR, 3.9; 95% CI, 1.2-13.1) were independent predictors of HIV seroconversion. CONCLUSIONS: HIV is currently spreading at an extremely high rate among MtF transgendered persons in San Francisco, especially those who are African Americans.

Adult↗
PubMed2001

Effect of case management on unmet needs and utilization of medical care and medications among HIV-infected persons.

BACKGROUND: Although case management has been advocated as a method for improving the care of chronically ill persons, its effectiveness is poorly understood. OBJECTIVE: To assess the effect of case managers on unmet need for supportive services and utilization of medical care and medications among HIV-infected persons. DESIGN: Baseline and follow-up interview of a national probability sample. SETTING: Inpatient and outpatient medical facilities in the United States. PARTICIPANTS: 2437 HIV-infected adults representing 217 081 patients receiving medical care. MEASUREMENTS: Outcomes measured at follow-up were unmet need for supportive services, medical care utilization (ambulatory visits, emergency department visits, and hospitalizations), and use of HIV medication (receipt of antiretroviral therapy and prophylaxis against Pneumocystis carinii pneumonia and toxoplasmosis). RESULTS: At baseline, 56.5% of the sample had contact with a case manager in the previous 6 months. In multiple logistic regression analyses that adjusted for potential confounders, contact with a case manager at baseline was associated with decreased unmet need for income assistance (odds ratio [OR], 0.57 [95% CI, 0.36 to 0.91]), health insurance (OR, 0.54 [CI, 0.33 to 0.89]), home health care (OR, 0.29 [CI, 0.15 to 0.56]), and emotional counseling (OR, 0.62 [CI, 0.41 to 0.94]) at follow-up. Contact with case managers was not significantly associated with utilization of ambulatory care (OR, 0.77 [CI, 0.57 to 1.04]), hospitalization (OR, 1.13 [CI, 0.84 to 1.54]), or emergency department visits (OR, 1.30 [CI, 0.97 to 1.73]) but was associated with higher utilization of two-drug (OR, 1.58 [CI, 1.23 to 2.03]) and three-drug (OR, 1.34 [CI, 1.00 to 1.80]) antiretroviral regimens and of treatment with protease inhibitors or non-nucleoside reverse transcriptase inhibitors (OR, 1.29 [CI, 1.02 to 1.64]) at follow-up. CONCLUSIONS: Case management appears to be associated with fewer unmet needs and higher use of HIV medications in patients receiving HIV treatment.

Adult↗
PubMed2001

HIV incidence among repeat HIV testers at a county hospital, San Francisco, California, USA.

OBJECTIVES: To estimate HIV incidence, characterize correlates of HIV seroconversion, and monitor temporal trends in HIV transmission among patients repeatedly tested for HIV by a county hospital in San Francisco. DESIGN: Retrospective longitudinal study. METHODS: HIV incidence was retrospectively calculated among persons voluntarily tested for HIV antibody more than once at San Francisco's county hospital or one of its affiliated satellite community clinics between 1993 and 1999. Linkage of HIV test results in computerized databases identified "seroconverters" as individuals who had a negative antibody test followed by a positive test. The interval between tests was used as the person-time at risk. Cox proportional hazards analysis identified correlates of HIV seroconversion. RESULTS: A total of 84 HIV seroconversions were identified among 2893 eligible patients repeatedly tested for HIV antibody over a cumulative 5860 person-years (PYs) (incidence of 1.4 per 100 PYs, 95% confidence interval [CI]: 1.2-1.7). The majority of seroconversions (71 [84.5%]) were among injection drug users (IDUs) (incidence of 2.0 per 100 PYs, CI: 1.6-2.4). HIV incidence was highest among men who have sex with men (MSM) who were also IDUs (incidence of 3.8 per 100 PYs, CI: 2.7-5.1) and lowest among non-IDUs, heterosexual men, and non-IDU women (incidence of 0.3 per 100 PYs, CI: 0.1-0.6). In multivariate analysis, correlates of HIV seroconversion were age 25 to 29 years (hazard ratio [HR] = 3.9, CI: 2.4-6.3), MSM (HR = 2.9, CI: 1.9-4.4), and IDU (HR = 3.2, CI: 1.8-5.8). Overall, no temporal trend in annual HIV incidence was noted during the study period; however, HIV incidence among MSM IDUs increased from 2.9 per 100 PYs in 1996 to 4.7 per 100 PYs in 1998. CONCLUSIONS: The rate of seroconversion in this hospital and affiliated clinic population is unexpectedly high. Moreover, HIV transmission among IDU patients has not decreased over the last several years. The San Francisco county hospital provides a high-risk sentinel population to monitor emerging trends in HIV transmission, especially among IDUs, and presents multiple opportunities for prevention interventions, because these patients are being seen repeatedly by clinicians.

AIDS Serodiagnosis↗
PubMed2001

Effect of highly active antiretroviral therapy on diagnoses of sexually transmitted diseases in people with AIDS.

BACKGROUND: There has been an increase in high-risk sexual behaviour and sexually transmitted diseases (STD) during the time period when highly active antiretroviral therapy (HAART) became widely available. We examined whether taking HAART increased the risk of acquiring an STD--an epidemiological marker of unsafe sex--in people with AIDS. METHODS: We did a computerised match of people in the San Francisco STD and AIDS registries. People with AIDS who were diagnosed before 1999 and alive in November, 1995, or later, were classified as having had an STD after AIDS diagnosis or not having had an STD after AIDS diagnosis. We used a Cox proportional hazards model to see whether use of antiretroviral therapy was associated with acquiring an STD after AIDS, after adjustment for sex, age, race, HIV-1 risk category, and CD4 count at AIDS diagnosis. FINDINGS: People with AIDS who had had HAART showed an independent increase in the risk of developing an STD (hazard ratio 4.10; 95% CI 2.84-5.94). Americans of African origin, younger age, and higher CD4 count at AIDS diagnosis were also associated with acquiring an STD after AIDS. The number of people living with AIDS who acquired an STD increased over time from 60 (0.66%) in 1995 to 113 (1.32%) in 1998 (p<0.001). INTERPRETATION: We have shown that people on HAART are more likely to develop an STD, an epidemiological marker of unsafe sex. More intensive risk-reduction counselling and STD screening for people with AIDS is needed.

AIDS-Related Opportunistic Infections↗
PubMed2001

Feasibility of postexposure prophylaxis (PEP) against human immunodeficiency virus infection after sexual or injection drug use exposure: the San Francisco PEP Study.

The feasibility of providing postexposure prophylaxis (PEP) after sexual or injection drug use exposures to human immunodeficiency virus (HIV) was evaluated. PEP was provided within 72 h to individuals with exposures from partners known to have or to be at risk for HIV infection. PEP consisted of 4 weeks of antiretroviral medications and individually tailored risk-reduction and medication-adherence counseling. Among 401 participants seeking PEP, sexual exposures were most common (94%; n=375). Among sexual exposures, receptive (40%) and insertive (27%) anal intercourse were the most common sexual acts. The median time from exposure to treatment was 33 h. Ninety-seven percent of participants were treated exclusively with dual reverse-transcriptase inhibitors, and 78% completed the 4-week treatment. Six months after the exposure, no participant developed HIV antibodies, although a second PEP course for a subsequent exposure was provided to 12%. PEP, after nonoccupational HIV exposure, is feasible for persons at risk for HIV infection.

Adolescent↗
PubMed2001

Barriers to getting needed services for Ryan White CARE clients.

To determine why HIV-infected persons do not access needed services, we interviewed clients of Ryan White CARE-funded agencies in San Francisco, San Mateo and Marin Counties. From July to September 1996, we interviewed 519 clients receiving services at 65 CARE-funded sites. Just over half the clients (54.5%) had at least one unmet service need in the previous four months; persons in an unstable living situation and those with lower perceived health status were significantly more likely to have an unmet need. For persons with unmet needs, agency barriers were most common (54.0%), followed by emotional issues (44.8%), lack of information (44.0%) and financial/practical barriers (19.4%). None of the client characteristics (sex, race/ethnicity, age, living situation, perceived health status and risk group) were consistently or significantly (p < 0.05) associated with specific barriers. We believe that the similarity between clients with and without unmet needs reflects the success of CARE in eliminating many barriers. However, the persistence of certain barriers and lack of sub-group-specific barriers suggests the need for individualized interventions to improve service delivery, publicize service availability and address the emotional barriers to accessing HIV-related care.

Adult↗
PubMed2001

Cost-effectiveness of prevention referrals for high-risk HIV-negatives in San Francisco.

We retrospectively assessed the cost-effectiveness of providing prevention referrals to high-risk seronegatives at HIV test sites in San Francisco. We examined the costs and effects from the perspectives of society and the San Francisco Department of Public Health (SFDPH). Cost categories assessed included referral materials, counsellor training and time required to make referrals, prevention services and the value of client time. Effect data are drawn from a study of 289 high-risk seronegatives and the published literature, and are applied to a city-wide caseload of 6,626 high-risk seronegatives. We estimate that a city-wide programme in San Francisco averts two HIV infections per year and yields net savings to society of $43,765, with a cost to the SFDPH of $20,738 per HIV infection averted. We conclude that providing HIV prevention referrals to high-risk seronegatives receiving antibody testing imposes significant costs, but has attractive cost-effectiveness when applied to a large high-risk population.

Adult↗
PubMed2001

Risk of infection from needle reuse at a phlebotomy center.

OBJECTIVES: This study determined infection risk for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) from needle reuse at a phlebotomy center that possibly exposed 3810 patients to infection. METHODS: We used a model for the risk of infection per blood draw, supplemented by subsequent testing results from 1699 patients. RESULTS: The highest risk of transmission was for HBV infection: 1.1 x 10(-6) in the best case and 1.2 x 10(-3) in the (unlikely) worst case. Subsequent testing yielded prevalence rates of 0.12%, 0.41%, and 0.88% for HIV, HBV, and HCV, respectively, lower than National Health and Nutrition Examination Survey III prevalence estimates. CONCLUSIONS: The infection risk was very low; few, if any, transmissions are likely to have occurred.

California↗
PubMed2000

Evaluating national HIV prevention indicators: a case study in San Francisco.

OBJECTIVES: To field-test the availability, interpretability, and programmatic usefulness of 37 proposed national HIV prevention indicators (HPI) intended to evaluate community-level impact of HIV prevention efforts in San Francisco. METHODS: HPI were defined for four populations (high risk heterosexuals, injecting drug users, men who have sex with men, and childbearing women) and for four domains (biological, behavioral, service, and socio-political). HPI were obtained from existing data sources only. Trends in HPI were examined from 1990 to 1997. RESULTS: Existing data provided 29 (78%) of the 37 proposed HPI; eight HPI were not available because California does not have HIV case reporting. Interpretation was limited for several HPI due to small sample size, inconsistencies in data collection, or lack of contextual information. Data providing behavioral HPI were scarce. HPI were consistent with historical patterns of HIV transmission in San Francisco but also highlighted new and worrisome trends. Notably, HPI identified recent increases in risk for HIV transmission among men who have sex with men. CONCLUSIONS: Despite limitations, the proposed national HPI provided evidence of the aggregate effectiveness of prevention efforts in San Francisco. Supplemental or local HPI are needed to fill data gaps, add context, and increase the scope and programmatic usefulness of the national HPI.

Centers for Disease Control and Prevention, U.S.↗
PubMed2000

Tracing a syphilis outbreak through cyberspace.

CONTEXT: A recent outbreak of syphilis among users of an Internet chat room challenged traditional methods of partner notification and community education because locating information on sexual partners was limited to screen names and privacy concerns precluded identifying sexual partners through the Internet service provider. OBJECTIVES: To determine the association of Internet use and acquisition of syphilis and to describe innovative methods of partner notification in cyberspace. DESIGN, SETTING, AND PATIENTS: Outbreak investigation conducted at the San Francisco (Calif) Department of Public Health (SFDPH) in June-August 1999 of 7 cases of early syphilis among gay men linked to an online chat room; case-control study of 6 gay men with syphilis reported to SFDPH in July-August 1999 (cases) and 32 gay men without syphilis who presented to a city clinic in April-July 1999 (controls). MAIN OUTCOME MEASURES: Association of syphilis infection with Internet use, Internet use among cases vs controls, and partner notification methods and partner evaluation indexes. RESULTS: During the outbreak, cases were significantly more likely than controls to have met their sexual partners through use of the Internet (67% vs 19%; odds ratio, 8.7; P =.03). We notified and confirmed testing for 42% of named partners; the mean number of sexual partners medically evaluated per index case was 5.9. CONCLUSIONS: In this study, meeting sexual partners through the Internet was associated with acquisition of syphilis among gay men. Public health efforts must continually adapt disease control procedures to new venues, carefully weighing the rights to privacy vs the need to protect public health. JAMA. 2000;284:447-449

Adult↗
PubMed2000

Impact of protease inhibitors and other antiretroviral treatments on acquired immunodeficiency syndrome survival in San Francisco, California, 1987-1996.

The authors assessed temporal trends in acquired immunodeficiency syndrome (AIDS) survival for 15,271 persons in San Francisco, California, diagnosed between 1987 and 1996 with an opportunistic illness included in the 1987 AIDS case definition. Predictors of survival were evaluated for 5,686 persons who were diagnosed between 1993 and 1996 and met the 1993 AIDS case definition. Median survival was 19 months for persons diagnosed between 1987 and 1989, 17 months for persons diagnosed between 1990 and 1992, 15 months for persons diagnosed between 1993 and 1994, and 31 months for persons diagnosed between 1995 and 1996. Decreased mortality was associated with use of antiretroviral therapy without protease inhibitors before AIDS (relative hazard (RH) = 0.88, 95% confidence interval (CI): 0.8, 1.0) and after AIDS (RH = 0.83, 95% CI: 0.7, 0.9) and use of antiretroviral agents with protease inhibitors before AIDS (RH = 0.25, 95% CI: 0.2, 0.3) and after AIDS (RH = 0.36, 95% CI: 0.3, 0.4). Increased mortality was found for persons aged > or = 40 years (RH = 1.43, 95% CI: 1.3, 1.6), persons initially diagnosed with an opportunistic illness (RH = 1.97, 95% CI: 1.8, 2.2), and homosexual injection drug users (RH = 1.33, 95% CI: 1.2, 1.5). Survival after AIDS has increased. Treatment with antiretroviral agents, particularly protease inhibitors, strongly predicts improved survival.

Acquired Immunodeficiency Syndrome↗
PubMed2000

HIV prevalence and associated risks in young men who have sex with men. Young Men's Survey Study Group.

CONTEXT: Studies conducted in the late 1980s on human immunodeficiency virus (HIV) infection among older men who have sex with men (MSM) suggested the epidemic had peaked; however, more recent studies in younger MSM have suggested continued high HIV incidence. OBJECTIVE: To investigate the current state of the HIV epidemic among adolescent and young adult MSM in the United States by assessing the prevalence of HIV infection and associated risks in this population in metropolitan areas. DESIGN: The Young Men's Survey, a cross-sectional, multisite, venue-based survey conducted from 1994 through 1998. SETTING: One hundred ninety-four public venues frequented by young MSM in Baltimore, Md; Dallas, Tex; Los Angeles, Calif; Miami, Fla; New York, NY; the San Francisco (Calif) Bay Area; and Seattle, Wash. SUBJECTS: A total of 3492 15- to 22-year-old MSM who consented to an interview and HIV testing. MAIN OUTCOME MEASURES: Prevalence of HIV infection and associated characteristics and risk behaviors. RESULTS: Prevalence of HIV infection was high (overall, 7.2%; range for the 7 areas, 2.2%-12. 1%) and increased with age, from 0% among 15-year-olds to 9.7% among 22-year-olds. Multivariate-adjusted HIV infection prevalence was higher among blacks (odds ratio [OR], 6.3; 95% confidence interval [CI], 4.1-9.8), young men of mixed or other race (OR, 4.8; 95% CI, 3. 0-7.6), and Hispanics (OR, 2.3; 95% CI, 1.5-3.4), compared with whites (referent) and Asian Americans and Pacific Islanders (OR, 1. 1; 95% CI, 0.5-2.8). Factors most strongly associated with HIV infection were being black, mixed, or other race; having ever had anal sex with a man (OR, 5.0; 95% CI, 1.8-13.8); or having had sex with 20 or more men (OR, 3.0; 95% CI, 2.0-4.7). Only 46 (18%) of the 249 HIV-positive men knew they were infected before this testing; 37 (15%) were receiving medical care for HIV, and 19 (8%) were receiving medical drug therapy for HIV. Prevalence of unprotected anal sex during the past 6 months was high (overall, 41%; range, 33%-49%). CONCLUSIONS: Among these young MSM, HIV prevalence was high, underscoring the need to evaluate and intensify prevention efforts for young MSM, particularly blacks, men of mixed race or ethnicity, Hispanics, and adolescents. JAMA. 2000;284:198-204

AIDS Serodiagnosis↗
PubMed2000

Very young gay and bisexual men are at risk for HIV infection: the San Francisco Bay Area Young Men's Survey II.

OBJECTIVES: To compare HIV seroprevalence and sexual risk behavior among very young gay and bisexual men (aged 15-17 years) and their older counterparts (aged 18-22 years). To examine drug-use patterns and correlates of sexual risk behavior in both of these age groups. DESIGN AND METHODS: An interviewer-administered cross-sectional survey of 719 gay and bisexual males between 15 and 22 years old was conducted through a venue-based sampling design. Blood specimens were collected and tested for HIV antibodies, hepatitis B, and syphilis. Interviews assessed sexual and drug-use behavior as well as psychosocial variables believed to be related to sexual risk-taking, including self-acceptance of gay or bisexual identity, perceptions of peer norms concerning safer sex, and perceptions of the ability to practice safer sex (safer sex self-efficacy). RESULTS: Of the 719 participants, 100 (16.2%) were aged between 15 and 17 years. HIV seroprevalence was somewhat lower among those aged 15 to 17 years (2.0%) compared with those aged 18 to 22 years (6.8%). Overall, the prevalence of hepatitis-B core antibody was significantly lower in the younger age group (5.0%) than in the older group (14.1%). The men aged 15 to 17 years used alcohol, ecstasy, and heroin less frequently than those aged 18 to 22 years. The age groups did not differ in the proportion of men who reported any unprotected anal intercourse in the previous 6 months (31.2%). In both age groups, use of amphetamines, ecstasy, and amyl nitrate was associated with unprotected anal intercourse. Self-acceptance of gay or bisexual identity was related to less sexual risk for those aged 15 to 17 years. In both age groups, greater safer sex self-efficacy was linked to less HIV sexual risk-taking. In the younger group, perceptions of peer norms that support safer sex were related to less risk behavior. CONCLUSIONS: Very young gay and bisexual men engage in unprotected anal sex at rates comparable with those for their somewhat older counterparts, raising serious concern over their risk of acquiring HIV infection. To prevent seroconversions, interventions must target those <18 years of age, and prevention programs should address the use of certain drugs in relation to sex and sexual risk-taking. To be most effective, programs should develop innovative communication strategies to take into account lack of self-acceptance of gay or bisexual identity and low self-efficacy for practicing safer sex.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗