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Biomedical subjects

Thomas J Coates

Publications and source records attributed to Thomas J Coates.

At least 19 recordsLinked to original sources
PubMed2007

Partner notification for sexually transmitted diseases in Peru: knowledge, attitudes, and practices in a high-risk community.

OBJECTIVES: Notification and treatment of sex partners after diagnosis of a sexually transmitted disease (STD) is essential to reduce reinfection and further transmission. GOAL: The goal of this study was to determine the prevalence of partner notification and subsequent health-seeking behavior in a high-risk population in Lima, Peru. STUDY DESIGN: STD-infected participants of an HIV/STD prevention trial completed a questionnaire concerning partner notification. RESULTS: Of the 502 STD-positive subjects, 287 completed the survey. Among survey participants, 65% informed their primary partner and 10.5% informed casual or anonymous partners. Reasons for failure to notify varied by partner type and included not understanding the importance of partner notification, embarrassment, fear of rejection, and inability to locate the partner. When notified, approximately one third of all partners sought medical attention. CONCLUSIONS: Partner notification in Peru is limited by relationship dynamics, social stigma, and limited contact information. Interventions could emphasize the importance of notification, improvement of communication skills, and introduce contact tracing programs (including Internet-based systems) and expedited partner therapy.

Adolescent↗
PubMed2006

Risk factors for HIV infection among men who have sex with men.

OBJECTIVES: Risk factors for HIV acquisition were examined in a recent cohort of men who have sex with men (MSM). DESIGN: A longitudinal analysis of 4295 HIV-negative MSM enrolled in a randomized behavioral intervention trial conducted in six US cities. METHODS: MSM were enrolled and assessed for HIV infection and risk behaviors semi-annually, up to 48 months. RESULTS: In multivariate analysis, men reporting four or more male sex partners, unprotected receptive anal intercourse with any HIV serostatus partners and unprotected insertive anal intercourse with HIV-positive partners were at increased risk of HIV infection, as were those reporting amphetamine or heavy alcohol use and alcohol or drug use before sex. Some depression symptoms and occurrence of gonorrhea also were independently associated with HIV infection. The attributable fractions of high number of male partners, use of alcohol or drugs before sex, and unprotected receptive anal intercourse with unknown status partners and the same with presumed negative partners accounted for 32.3, 29.0, 28.4 and 21.6% of infections, respectively. CONCLUSIONS: The challenge is to develop strategies to identify men in need. Interventions are needed to help men reduce their number of sexual partners, occurrences of unprotected anal intercourse, alcohol or drug use before sex and address other mental health issues.

Adult↗
PubMed2006

Removing barriers to knowing HIV status: same-day mobile HIV testing in Zimbabwe.

OBJECTIVES: We developed a mobile HIV voluntary counseling testing (VCT) strategy. Our aims were (1) to describe those using the services, (2) to assess the acceptability of such services, (3) to assess reasons for not testing previously, and (4) to compare those who used the services with those who did not to determine how to increase acceptability. METHODS: We provided free anonymous mobile VCT using 2 rapid HIV tests in 12 marketplaces in Epworth and Seke, Zimbabwe. Qualitative interviews were conducted to assess motivations for and barriers to testing. A subsample of HIV testers and individuals near testing vans who declined testing (nontesters) completed a questionnaire. RESULTS: A total of 1099 individuals participated in mobile VCT between March 2002 and August 2003. The proportion of participants infected with HIV was 29.2%. Overall, 98.8% of participants elected to receive HIV test results the same day. Reasons for not testing previously were often logistic (eg, inconvenience of hours [25.6%] and location [20.7%] or cost [8%]). Those who used the same-day mobile testing services (testers vs. nontesters) perceived themselves at higher risk for HIV infection (adjusted odds ratio [AOR] = 1.8) but were less likely to have known people with HIV (AOR = 0.49) or where to get tested (AOR = 0.57). CONCLUSIONS: Same-day HIV testing in community settings seems to be acceptable in sub-Saharan Africa. Barriers to HIV testing are often logistic and can be overcome with community-based strategies. These strategies need to be refined to address the needs of those not using mobile testing services.

AIDS Serodiagnosis↗
PubMed2006

Syphilis treatment and HIV infection in a population-based study of persons at high risk for sexually transmitted disease/HIV infection in Lima, Peru.

OBJECTIVES: The objective of this study was to characterize syphilis epidemiology and the relationship of HIV status and initial rapid plasma reagin (RPR) titer to syphilis treatment in Lima, Peru. STUDY DESIGN: We screened 1,261 individuals at high risk for sexually transmitted diseases for syphilis and HIV infection. Syphilis was treated with penicillin injection or doxycycline; treatment was repeated in unresponsive cases. RESULTS: : The prevalence of syphilis was 7.7%, 1-year incidence rate was 4.7%, and reinfection rate was 42.7%. The treatment success rate was 93.4% (71 of 76); those with initial RPR titers or=1:16. HIV infection was associated with syphilis, prevalent in 15.6% and 3.7% of those with and without syphilis, respectively (P < 0.001), but did not affect treatment success (90.9% vs. 93.8%). CONCLUSIONS: Syphilis was common, associated with HIV infection, and less responsive to therapy in those with initial RPR titers <or=1:8. HIV infection did not affect syphilis treatment success rates.

Adolescent↗
PubMed2005

Seroconversion following nonoccupational postexposure prophylaxis against HIV.

BACKGROUND: The efficacy of antiretroviral postexposure prophylaxis (PEP) against infection with human immunodeficiency virus (HIV) following occupational exposures has prompted the use of PEP after nonoccupational exposures. There are, however, important differences between occupational and nonoccupational exposures, and the effectiveness of PEP following nonoccupational exposure is unknown. We sought to describe the occurrence and circumstances of HIV seroconversion following nonoccupational PEP. METHODS: HIV uninfected individuals reporting potential sexual or injection drug use exposures to HIV in the preceding 72 h received a 28-day regimen of antiretroviral therapy and counseling in a nonrandomized trial. The level of HIV antibody was measured 12 weeks after PEP initiation. RESULTS: Of 877 exposed subjects, 702 were evaluable 12 weeks after exposure. Seroconversion was detected in 7 subjects (1%; 95% confidence interval, 0.4%-2%). Three seroconverters reported having no exposures after PEP initiation and, thus, probably represent evidence of chemoprophylactic failure. In the other 4 subjects, additional exposures to HIV after PEP initiation or detection of HIV RNA in plasma specimens obtained at baseline precluded determination of the source of seroconversion. No exposure source was available to assess genetic concordance with the seroconverter's virus. CONCLUSIONS: As for occupational exposure, PEP is not completely effective in preventing HIV infection following nonoccupational exposure. Therefore, primary prevention remains essential. In contrast to the occupational setting, the potential source of exposure is rarely available for testing in the nonoccupational setting, and exposures are often not isolated. Thus, it is often impossible to determine whether seroconversion resulted from failure of PEP or from other exposures, posing difficulties for future comparative studies seeking to evaluate the effectiveness of PEP.

Anti-HIV Agents↗
PubMed2005

Longitudinal patterns of methamphetamine, popper (amyl nitrite), and cocaine use and high-risk sexual behavior among a cohort of san francisco men who have sex with men.

Most prior studies examining drug use among men who have sex with men (MSM) have been cross-sectional or retrospective and have not determined whether periods of increased drug use are associated with high-risk sexual behavior at the individual level. In this article, we describe patterns of use of methamphetamines, poppers, and sniffed cocaine and sexual risk behavior among 736 San Francisco MSM enrolled in the EXPLORE study and followed for up to 48 months. In longitudinal analysis, use of methamphetamines, poppers, and sniffed cocaine declined during follow-up. However, compared with older participants, younger participants were more likely to increase their drug use over time. Results of conditional logistic regression demonstrated that high-risk sexual behavior was more common during reporting periods characterized by increased methamphetamine, poppers, or sniffed cocaine use. This within-person analysis found that compared with periods of no drug use, periods of both light drug use (less than weekly use of drugs) and heavier drug use (at least weekly use of at least one drug) were significantly associated with increased risk of engaging in unprotected anal sex with an HIV-positive or unknown-status partner. These results suggest that even intermittent, recreational use of these drugs may lead to high-risk sexual behavior, and that, to reduce and prevent risks of HIV, no level of use of these drugs should be considered "safe." HIV prevention interventions should target MSM who report either light or heavy use of methamphetamines, poppers, and sniffed cocaine.

Adolescent↗
PubMed2005

The epidemiology of herpes simplex virus type 2 infection in low-income urban populations in coastal Peru.

OBJECTIVE: The objective of this study was to determine the epidemiology of herpes simplex virus type 2 (HSV-2) in general and socially marginalized populations of low-income, urban, coastal Peru. STUDY: Two low-income populations were administered an epidemiologic survey and serologic tests, determining risk behavior, HSV-2, and HIV prevalence. RESULTS: In the socially marginalized population, HSV-2 prevalence was 72.3% in men who have sex only with men (MSOM), 42.5% in women, and 20.7% in men. In the general population, HSV-2 prevalence was 20.5% in women and 7.1% in men. In all groups except the male general population, HSV-2 prevalence increased with age or number of sexually active years (both P <0.001). HSV-2 infection was associated with HIV infection in MSOM (P <0.023) and other socially marginalized men (P <0.01). CONCLUSION: HSV-2 was common in both low-income populations, and control programs are needed in Peru given high prevalence and association with HIV infection. Prevention of HSV-2 infection should target individuals before they become sexually active.

Adolescent↗
PubMed2004

Cost-effectiveness of HIV postexposure prophylaxis following sexual or injection drug exposure in 96 metropolitan areas in the United States.

OBJECTIVES: To evaluate the cost-effectiveness of HIV postexposure prophylaxis (PEP) following sexual or injection-related exposures in 96 metropolitan statistical areas in the United States (MSA). DESIGN: Empirical, model-based cost-effectiveness analysis. METHODS: Epidemiological and population size estimates from the literature were combined with information about the distribution of exposure types, PEP completion rate, proportion of source partners known to be HIV infected, and PEP program costs obtained from a feasibility study of PEP in San Francisco to estimate the cost-effectiveness of hypothetical PEP programs in each of the 96 MSA. The effectiveness of combination antiretroviral therapy following sexual or drug use-related exposures, which is presently not known, was assumed equal to the effectiveness of zidovudine monotherapy in the occupational setting. The main outcome measure was the cost-utility ratio, defined as the cost per quality-adjusted life year (QALY) saved by the PEP intervention. RESULTS: The cost-utility ratios for the 96 MSA ranged from 4137 dollars to 39,101 dollars per QALY saved; only two of the ratios exceeded 30,000 dollars per QALY saved. Combined across the 96 MSA, the hypothetical PEP programs would reach nearly 20,000 clients at a total cost of approximately 22 million dollars. The overall cost-utility ratio across MSA was 12,567 dollars per QALY saved. The majority of the HIV infections prevented by PEP were among men and women who reported receptive anal intercourse exposure. CONCLUSIONS: PEP following sexual or drug use-related exposures could be a cost-effective complement to existing HIV-prevention efforts in most MSA across the United States.

Chemoprevention↗
PubMed2004

HIV RNA testing in the context of nonoccupational postexposure prophylaxis.

BACKGROUND: The specificity and positive predictive value of human immunodeficiency virus (HIV) RNA assays have not been evaluated in the setting of postexposure prophylaxis (PEP). METHODS: Plasma from subjects enrolled in a nonoccupational PEP study was tested with 2 branched-chain DNA (bDNA) assays, 2 polymerase chain reaction (PCR) assays, and a transcription-mediated amplification (TMA) assay. Assay specificity and positive predictive value were determined for subjects who remained negative for HIV antibody for >or=3 months. RESULTS: In 329 subjects examined, the lowest specificities (90.1%-93.7%) were seen for bDNA testing performed in real time. The highest specificities were seen with batched bDNA version 3.0 (99.1%), standard PCR (99.4%), ultrasensitive PCR (100%), and TMA (99.6%) testing. Only the 2 assays with the highest specificities had positive predictive values >40%. For the bDNA assays, increasing the cutoff point at which a test is called positive (e.g., from 50 copies/mL to 500 copies/mL for version 3.0) increased both specificity and positive predictive values to 100%. CONCLUSIONS: The positive predictive value of HIV RNA assays in individuals presenting for PEP is unacceptably low for bDNA-based testing and possibly acceptable for PCR- and TMA-based testing. Routine use of HIV RNA assays in such individuals is not recommended.

Anti-HIV Agents↗
PubMed2004

Substance use and sexual risk: a participant- and episode-level analysis among a cohort of men who have sex with men.

Prior reports associating substance use with sexual risk behavior have generally used summary measures and have not adjusted for participants' background levels of substance use. In this 1999-2001 US study (the EXPLORE study), the authors determined whether substance use during sex was independently associated with sexual risk during recent sexual episodes, as reported by 4,295 human immunodeficiency virus-negative men who have sex with men. The main outcome measure was serodiscordant unprotected anal sex (SDUA). The influence of participant-level characteristics was examined by using repeated-measures logistic models. In assessing the influence of episode-level predictors on SDUA, the influence of participant-level characteristics, including 6-month substance use, was removed by using conditional logistic regression, in effect making each participant his own control. The authors also adjusted for partner characteristics. Eleven percent of participants reported heavy alcohol use, 37% used poppers, 19% sniffed cocaine, and 13% used amphetamines. In the participant-level analysis, use of poppers, amphetamines, and sniffed cocaine as well as heavy alcohol use in the prior 6 months were independently associated with SDUA. In the conditional analysis, consumption of > or = 6 alcoholic drinks or use of poppers, amphetamines, or sniffed cocaine just before or during sex was independently associated with SDUA. The authors concluded that programs aimed at preventing human immunodeficiency virus transmission should emphasize the influence of substance use during sex on increased risk behavior.

Adolescent↗
PubMed2004

Use of postexposure prophylaxis against HIV infection following sexual exposure does not lead to increases in high-risk behavior.

BACKGROUND: The effectiveness of postexposure prophylaxis (PEP) following occupational exposure to HIV has prompted advocacy for PEP following sexual or drug-use exposures. OBJECTIVE: To evaluate the concern that the availability of PEP for sexual or drug-use exposures might result in behavioral disinhibition. DESIGN: Non-randomized trial of 397 adults with high-risk sexual or drug-use exposures within the prior 72 h. INTERVENTIONS: Antiretroviral medication for 4 weeks and five counseling sessions. MAIN OUTCOME MEASUREMENTS: Participants were followed for 12 months for repeat request for PEP and for changes compared with pre-enrollment in overall high-risk behavior and the acquisition of sexually transmitted diseases (STD) and HIV. RESULTS: After 12 months following receipt of PEP, the majority of participants (83%) did not request a repeat course of PEP. At 12 months after exposure, 73% of participants reported a decrease compared with baseline in the number of times they had performed high-risk sexual acts; 13% reported no change, and 14% had an increase. Most participants (85%) had no change in the incidence of STD; 8.5% had a decrease and 6.8% an increase. Three homosexual men seroconverted for HIV (none associated with the presenting exposure) for a rate of 1.2/100 person-year, equivalent to rates in San Francisco among all homosexual men. CONCLUSIONS: After receipt of PEP consisting of antiretroviral medication and behavioral counseling following a potential sexual exposure to HIV, most individuals do not increase high-risk behavior. Coupled with prior safety and feasibility data, this lack of behavioral disinhibition suggests that use of PEP should be routinely considered following high-risk sexual exposures.

Adult↗
PubMed2004

Cost-effectiveness of postexposure prophylaxis after sexual or injection-drug exposure to human immunodeficiency virus.

BACKGROUND: The cost-effectiveness of interventions that provide human immunodeficiency virus (HIV) postexposure prophylaxis (PEP) to individuals after sexual or injection-drug use exposures depends on the distribution of exposure routes, prevalence of infection among source partners, adherence to PEP regimens, medical care costs, and prevailing epidemiologic contexts, among other factors. OBJECTIVE: To determine the cost-effectiveness of a comprehensive program to prevent HIV infection after sexual or injection-drug use exposure for 401 persons seeking PEP in an urban community. METHODS: We conducted a retrospective cost analysis to evaluate the cost of the PEP intervention, then combined this information with model-based effectiveness estimates to determine the PEP program's "cost-utility ratio," which is the ratio of net program costs to the total number of quality-adjusted life-years (QALYs) saved by the program. RESULTS: The average cost of the PEP regimen was $1222, and the total cost of the program was $450 970. The PEP program prevented an estimated 1.26 HIV infections, saved 11.74 QALYs, and averted $281 323 in future HIV-related medical care costs. The overall cost-utility ratio was $14 449 per QALY saved. When analysis was restricted to men reporting receptive anal intercourse, the savings in averted HIV-related medical care costs exceeded the cost of the program. The results were generally robust to changes in key parameter values but were sensitive to assumptions about the HIV transmission probability for receptive anal intercourse. CONCLUSIONS: For this study population, HIV PEP was cost-effective by conventional standards and cost-saving for persons seeking PEP after male-male receptive anal intercourse.

Anti-HIV Agents↗
PubMed2004

Clients of female sex workers in Lima, Peru: a bridge population for sexually transmitted disease/HIV transmission?

OBJECTIVES: The objectives of this study were to determine the prevalence of risk behaviors, gonorrhea, and chlamydia in clients of female sex workers, and to compare them with men selected from the general population. STUDY DESIGN: We conducted a cross-sectional study of men recruited from commercial sex venues in Lima, Peru from January to February 2002. Subjects answered a survey and provided a urine sample. RESULTS: Men reported that in the recently concluded commercial sex encounter, 95.8% used condoms, and 85.8% always used condoms with female sex workers. Only 16% reported always using condoms with their stable partners; 50.8% always used condoms with casual, noncommercial partners; and 59.6% always used condoms for homosexual anal sex. There were 8 (2%) cases of chlamydia and no cases of gonorrhea. CONCLUSIONS: Clients of female sex workers report high rates of condom use with sex workers and a low prevalence of chlamydia and gonorrhea. It is unlikely that they constitute a bridging population.

Adolescent↗
PubMed2003

Why HIV infections have increased among men who have sex with men and what to do about it: findings from California focus groups.

A resurgence of sexual risk taking, STDs, and HIV incidence has been reported among men who have sex with men (MSM) in several countries. We asked 113 MSM in 12 focus groups conducted in five California cities to identify factors leading to increased risk taking and assess prevention messages to reduce risk in this population. Participants perceived that HIV risk taking has increased because (1) HIV is not the threat it once was due to more effective therapies, (2) MSM communicate less about HIV, and social support for being safe has decreased, and (3) community norms have shifted such that unsafe sex is more acceptable. The prevention messages ranked most likely to motivate risk reduction encouraged individuals to seek social support from friends. Themes ranked least likely to succeed were those that described the negative consequences of HIV or reinforced existing safer sex messages.

Adolescent↗
PubMed2003

High-risk behaviors among men who have sex with men in 6 US cities: baseline data from the EXPLORE Study.

OBJECTIVES: We describe the prevalence of risk behaviors at baseline among men who have sex with men (MSM) who were enrolled in a randomized behavioral intervention trial conducted in 6 US cities. METHODS: Data analyses involved MSM who were negative for HIV antibodies and who reported having engaged in anal sex with 1 or more partners in the previous year. RESULTS: Among 4295 men, 48.0% and 54.9%, respectively, reported unprotected receptive and insertive anal sex in the previous 6 months. Unprotected sex was significantly more likely with 1 primary partner or multiple partners than with 1 nonprimary partner. Drug and alcohol use were significantly associated with unprotected anal sex. CONCLUSIONS: Our findings support the continued need for effective intervention strategies for MSM that address relationship status, serostatus of partners, and drug and alcohol use.

Adolescent↗