Abstract objective: to detect and quantify the current risk factors for HIV serum transformation in gay men who were repeatedly tested in sexual health clinics.
Design: unparalleled case-control studies were conducted in London, Brighton and Manchester, United Kingdom.
Methods: 75 cases (
The most recent HIV positive test has been negative in the last two years)
And 157 control (
In the past two years, the most recent HIV negative test was after the previous negative test)
Complete the computer-
The focus of assisting self-interviews is on sexuality and lifestyle between HIV testing.
Results: in society-
Demographics, years since sexual relations with men, the lifetime number of HIV tests, the reasons for seeking previous HIV tests, and the interval between the last HIV tests (meanu200a=u200a10. 5 months).
The risk factors between the examinations include unprotected receptive anal sex (URAI)
With partners who are not considered HIV negative (
Adjust the odds (AOR)
95% confidence interval 4. 1, 1. 8 to 9. 3)
, In this case, the risk increases with the use of nitrite inhalation, the acceptance of ejaculation, and the increasing number of partners.
The independent risk of unprotected anal insertion was also detected (UIAI)
There is more than one person (AOR 2. 7, 1. 3 to 5. 5)
And the use of nitrite inhalation (AOR 2. 4, 1. 1 to 5. 2).
Conclusion: unprotected anal sex with inconsistent HIV serum remains the main background of HIV transmission in gay men, and the risk of receiving ejaculation and using nitrite inhalation is increased.
Although URAI's risk of HIV transmission is widely recognized, this study highlights the risk of UIAI and, when HIV exposure occurs, nitrite inhalation may be an important promoter of transmission.
In British men between the sex still is HIV spread of main focus accounted for 2300 of new diagnosis report of 2005 more than estimation 84% of infection may be is in England.
1-2 monitoring of high-risk behaviors and sexually transmitted infections (STIs)
In men who have sex with men (MSM)
In recent years, the proportion of men who have sex with men reporting unprotected anal sex has risen to 42% in London in 2000, with sexually transmitted infections reaching record levels in England and Wales. 3 4 The re-
On 2004, syphilis occurred at the end of 1990 s and was present in sexually transmitted lymph swelling, which further raised concerns about the sexual health of men who have sex with men in the UK.
5 6 the HIV prevention strategy is based on the theory of what behaviors lead to HIV transmission (relative risk)
This kind of behavior is common among the concerned people (
Risk attributable).
Risk factor research is one of the earliest responses to the AIDS epidemic.
The empirical knowledge among men through sexually transmitted HIV is mainly derived from studies conducted during the first decade of the epidemic.
7-11 the biggest of them is more
The center's AIDS Cohort Study, conducted 12 times in the epicenter of the United States, found unprotected accepted anal sex (URAI)
As a major risk factor for HIV serum transformation, this discovery is repeated in most other studies.
Behaviors that increase the likelihood of exposure, such as a large number of sexual partners, and factors that are considered to increase the likelihood of transmission, such as the presence of other sexually transmitted infections, also have varying degrees of consistency reporting.
As HIV has far more sexual exposure than transmission, promoting HIV transmission is an important goal of prevention programmes when exposed to HIV.
Currently, the UK's HIV prevention strategy for men who have sex with men was first implemented in 1998 and updated in 2003 to identify HIV serums
Discordant unprotected anal intercourse, failure of condoms, HIV-free males introduce HIV-infected semen into the mouth or anus, concurrent transmission infection (
Especially gonoseria, syphilis, herpes)
And the absence after
Exposure Prevention for men exposed to HIV, as a relative and attributable risk behavior with sufficient evidence among men who have sex with men in the UK, deserves to be a target for population levels.
British Insight (
New serum transformation survey for gay men tested for HIV)
A project was set up in 2001 to determine whether these factors, which led to HIV serum transformation in men who had sex with men at the beginning of the 21 st century, are still up to date, are accompanied by new factors, if any, provide information on changes in these HIV prevention population goals/targets.
Case-materials and methods
A controlled study was conducted in seven sexual health clinics in London (5), Manchester (1)and Brighton (1)
This accounted for more than half of the HIV diagnosis obtained through sexual intercourse between British men.
Participants were recruited in stages from September 2002 to October 2004, and most clinics were recruited continuously for 12 months.
A subset of respondents selected with a destination participated-
Explore in-depth interviews with the background of HIV serum transformation.
Results of qualitative studies are reported separately.
14 cases of population studies (
HIV serum converter)
Defined as gay over the age of 16, recently had HIV positive test results in a participating clinic and HIV negative test results in the past two years.
The controls came from the same population, but in both cases there were HIV negative test results.
Excluded men, whose Test interval is less than three months, may be in the "window period" of antibody testing ".
Before being recruited, cases had time to adapt to their diagnosis, but were exposed within a month of testing HIV positive.
Controls were recruited immediately after receiving HIV negative test results and any
Test consultation.
The clinic staff identified and recruited participants and provided them with private space to complete the study questionnaire.
Computer learning program
Assist in self-interview (CASI)
Used to collect data from participants.
The content is guided by current and speculative theories on determinants of HIV transmission, asking questions from a range of existing studies, and conducting cognitive interview tests on the initial recruits.
CASI asks about key sexual behavior (
Inserted anal sex, accepted anal sex and accepted oral sex)
There are two different ways between their last two HIV tests.
First, they are required to report the total number of men based on perceived HIV status (
Known HIV positive, assumed HIV negative, unknown)
When sex happens
Second, they were asked to report the partner's specific behavior with up to three regular partners and to report the overall behavior with casual workers.
Participants were also asked how to use social and sexual sites as well as media forms used to meet sexual partners, event diagnosis of sexually transmitted infections, overall health, clinical depression, use alcohol and recreational drugs between their HIV tests.
The case completed the same CASI as the control and submitted their reply via the Internet.
The clinic did not have questionnaire data after submission.
Written informed consent is provided by all participants.
This study has been more than Southwest.
The center studies the ethics committee and the local ethics committee covering the place of participation.
Statistical analysis variables reviewed to determine its utilization of Stata with HIV serum conversion (version 9. 0;
University of Texas station Stata Corp . ).
Explore continuous variables using t-test.
For classification variables, ratio (OR)
95% confidence intervals (CI)
P-values were obtained by logistic regression.
Variables related to serum converters (p⩽0. 2)
Used as a predictive variable in a multivariate logistic regression model.
This provides a convenient way to control interest associations of any potential hybrid factor.
The model is built using an approximate-based hierarchical approach
A determinant framework similar to Boerma and Weir.
16 Backward elimination models were used to explore the remote factors and retain those of p ⩽ 0. 2.
For critical sexual variables, the multivariate analysis is limited to adjusting the URAI report for any male who is not considered HIV-negative.
Results a total of 75 HIV sero-converts and controls were recruited in the study, and 157 controls, with an overall response rate of 72%, with no significant difference in response rates between cases and controls.
In terms of demographics, the two groups were similar, with an average age of 35 for the last HIV test, over 90% of white people, about half of the educational level and under three
Number of employed persons (table 1). Seventy-
Participants described themselves as gay, and most people are open or fully open to other people's sexual behavior.
Sex and HIV testing history is also comparable to the reported average of 16 years since the first anal sex, 7 years since the first HIV test, a total of 6 HIV tests and an average interval of 10 cases.
Six months between the last two HIV tests (10. 5 for controls).
View this table: View the social demographics, sex, and HIV test history of the inline View pop-up table 1 INSIGHT case
Control study participants reported a median of 15 sexual partners in the interval compared to 12 in the control (pu200a=u200a0. 113).
Compared to 36% of the control groups, 47 of the reported cases had sex with at least one male who they knew was HIV positive, although the difference was not statistically significant.
Similarly, there was no significant difference in the number of sexual partners considered HIV negative or unidentified, which accounted for the majority of sexual contact.
Anal sex was reported in all cases and 97% of controls.
Factors associated with serum transformation between HIV testing, 83% of cases and 55% of Controls reported URAI, crude ratio (OR)3. 9 (2. 0 to 7. 7)
With the increase in the number of men, the risk is becoming more and more obvious (table 2).
28% of cases and 11% of Controls reported at least one URAI known to be HIV positive (OR 3. 2, 1. 6 to 6. 4).
This risk increases dramatically when nitrite inhalation is used (OR 9. 3, 3. 3 to 26. 2)
Where ejaculation occurs, especially where ejaculation occurs with more than one HIV-positive male (OR 5. 5, 1. 0 to 28. 9).
A similar pattern was observed between URAI and men with unknown HIV status (OR 4. 3, 2. 4 to 7. 8)
Although there is no further increase in the risk observed by the use of nitrite inhalation in this case, the risk of more men, ejaculation and ejaculation than one man has increased.
In contrast, no statistical association was found between HIV serum transformation and URAI practice in men considered to be HIV negative (table 2).
Identify significant risks in URAI with regular partners (OR 2. 4, 1. 4 to 4. 3)
And temporary workers (OR 3. 7, 2. 0 to 6. 8).
View this table: View the behavior of inline View pop-up table 2 INSIGHT case-
Comparative study-preventive anal insertion (UIAI)
76% of cases and 61% of control reports (OR 2. 1, 1. 1 to 3. 8)
There is more than one person's UIAI risk increase (OR 4. 5, 2. 5 to 8. 0)
And five or more men to a lesser extent (OR 2. 5, 1. 2 to 4. 9).
Although the risk of serum conversion in men reporting a known HIV positive and unknown status of UIAI has increased, there is no strong evidence that the risk of UIAI increases as the number of men increases.
After adjusting URAI with men believed to be HIV-negative, it was found that serum conversion was significantly associated with UIAI in more than one male (
Adjust the odds (AOR)2. 7, 1. 4 to 5. 2)
More than one person who is not considered HIV negative (AOR 2. 0, 1. 1 to 3. 7)
More than five of these people. AOR 2. 3, 1. 1 to 5. 1)(table 2).
Unprotected Receptive oral intercourse (UROI)
Almost reported.
Cases are more likely than controls to report that men with HIV-positive urri and men with unknown HIV status in urri ejaculate in the mouth.
However, after adjusting URAI with men believed to be HIV-negative, these behaviors were not found to be statistically significant.
Assisted sexual examination (
Sometimes and often reported as "never ")
Men showing serum transformation are more likely to report any oral anal exposure (rimming)
, Collective sex, accepting the use and deception of sexual toys (table 3).
However, there is no evidence of an increase in male risk of frequently engaging in these activities (data not shown).
Multiple models of these behaviors indicate that the Edge (AOR 3. 3, 1. 3 to 8. 5)
Punched (AOR 3. 1, 1. 4 to 7. 0)
According to the observed association (table 3).
View this table: View inline View pop-up table 3 in INSIGHT case association of other factors with HIV serum transformation
Control study participants
During the interval, 39% of cases and control reports were diagnosed as sexually transmitted infections (
Including when they last tested HIV).
Diagnosis of leucorrhea (OR 3. 6, 1. 7 to 7. 8)and syphilis (6. 0, 1. 1 to 31. 8)
All related to serum conversion;
However, only Leucorrhea is still statistically significant in the multivariate model (table 3).
Recreational drugs were reported in 93% of cases, and recreational drugs were reported in 85% of controls;
However, only 8% of cases and 3% of Controls reported any drug injection (Mainly steroids).
Any use of a submethyl-type inhalation, methamphetamine (MDMA, Ecstasy), ketamine, d-
Diethyl amine (LSD)
Viagra is significantly related to serum conversion (table 3).
However, an examination of the frequency of drug use (
Once, many times, regularly)
It was found that there was no obvious trend in drug use after serum conversion (data not shown).
Multivariate model of drug use (any)
Only nitrite inhalation related to serum transformation was found (AOR 3. 7, 1. 8 to 7. 8).
Reduced risk of cannabis use (AOR 0. 4, 0. 2 to 0. 9)
Although this "protective" effect is not obvious if cannabis is frequently used in the model.
Only 11% of cases and 12% of Controls reported no drinking (table 3). Ninety-
94% of cases and control reports encountered new sexual contact during the interval.
However, it is reported that none of the venues or media are associated with HIV serum transformation, although the multivariate model suggests that men using the internet are more likely to have serum transformation (AOR 1. 9, 1. 0 to 3. 4)
On the contrary, it is unlikely that a man who meets a man in the toilet (AOR 0. 3, 0. 1 to 0. 8)(table 3).
The final logistic regression model was used to test the relationship between variables found so far related to HIV serum transformation: URAI with partners who do not know HIV-negative;
More than one person's UIAI;
Diagnosis of leucorrhea;
Then trim; being fisted;
Meet men using the internet;
Any use of nitrite inhalation.
In the last model, an independent association of HIV serum transformation was found between URAI and unknown HIV-negative partners (AOR 4. 1, 1. 8 to 9. 3)
There is more than one person's UIAI (AOR 2. 7, 1. 3 to 5. 5)
And the use of nitrite inhalation (AOR 2. 4, 1. 1 to 5. 2).
Although the study did not find any new factors leading to HIV serum transformation in gay men in the UK, the results of the study re-examined
Highlight the risks associated with unprotected receptive anal intercourse and clarify the risks associated with the use of nitrite inhalation in this activity.
The risks associated with UIAI are also clear --
Many gay men may be mistaken for low-risk practices.
By recruiting men seeking repeat HIV testing at sexual health clinics, we conducted a sample survey of HIV-at-risk populations in particular.
The social demographics of cases and controls, year of risk and history of HIV testing are so similar, suggesting that the underlying bias inherent in this approach has been successfully controlled.
In such samples, the risk distribution of cases and controls is closely related to factors that promote transmission (
Not those who offer exposure)
It may be detected.
Despite this design, URAI was found to distinguish significantly between serum transformation and non-seroconverters;
This finding not only confirms early work, but also increases the likelihood that there is no significant increase in the key behavioral drivers of HIV transmission in this population, and the results of previous studies remain valid.
This study will underestimate the relative risk of some behaviors, as a control has chosen to face a higher risk of HIV serum transformation since repeated HIV tests.
The response rate of more than 70% is unlikely to introduce bias, and although recruitment bias is likely to exist, the indicators shown in Table 1 indicate that these biases have been controlled.
Using CASI may report sensitive behavior to the maximum extent, but this does not overcome the inherent recall bias of these studies.
Cases know their diagnosis, and controls also know that they are not infected, which can lead to different memories of risky behavior.
In single-variable and multi-variable analyses, the estimated odds of certain unprotected anal and oral sex factors were significantly different.
This may be due to some common reasons.
The linear relationship between these factors.
Our ability to detect less common risk factors may be limited by the sample size.
Contrary to the US findings, although more than 10% of participants reported an association of meth with serum transformation, we did not find any evidence, on the contrary, the drugs that stand out from our study are nitrite inhalation.
Earlier, the 11 th Research Center and the recent research center from North America have reported on the independent association.
18 19 simultaneous use of nitrite inhalation in HIV serum
Non-harmonious unprotected sexual intercourse promoting transmission is biologically reasonable.
20 However, an increase in risk may also be due to the use of nitrite inhalation to promote anal penetration and to the greater likelihood of use in "rough" sex.
In the multivariate analysis, which was later removed from the final model, it was found that factors related to serum conversion should not be excluded.
It has previously been reported that gonoseria infection is associated with HIV serum transformation.
11 One explanation is that men get Congo leucorrhea from the same partner they get HIV, and Congo leucorrhea has been shown to increase viral load in semen, thus increasing HIV
21 similarly, reported quarterly cases indicate that participation in this activity and taking "club" drugs may be a useful sign for men with increased risk of serum transformation.
Further research should investigate the role of drugs and alcohol in high-risk sexual behavior.
Unprotected anal intercourse with partners who are not considered HIV-negative remains the main route for gay men to obtain HIV in the UK from two behaviors increased when reaching multiple partners with an accepted partner, taking ejaculation and using nitrite inhalation at the same time increases the risk. This study confirms that the population level target of the Gay Men's HIV program should continue to focus on reducing serum response
Non-harmonious unprotected anal intercourse
While in the UK's Gay Men's HIV prevention strategy, the potential of nitrite inhalation as a communication facilitator has been recognized, it has not been targeted as a programme.
This study suggests that this should be considered, especially according to data that after alcohol, nitrite inhalation is the most widely used drug among gay people in the UK.
22 Therefore, we conclude that in gay men in the UK, the attributable risk of HIV serum transformation caused by nitrite inhalation is high and the use of these substances in HIV serum is reduced
Preventive programmes have made unprotected sexual intercourse, which is not harmonious, a goal at the population level.
This recommendation requires further study of the need to avoid the use of nitrite in HIV serum
Discordant unprotected anal intercourse and interventions that may meet these needs.
The study was funded by the Medical Research Council (
Strategic authorization number rw100183).
The authors would like to thank the staff involved in managing the research and recruitment of participants in the health clinic: Camden and Islington Community Health Services NHS Trust, Royal Free Hampstead NHS Trust, chelsea and Westminster Healthcare and NHS trust, King Healthcare NHS Trust, St. Mary Healthcare NHS Trust, Brighton NHS Trust, Manchester Central Healthcare NHS trust;
Andre Charlett of statistical advice;
Professor Jonathan Elford's contribution to the insight questionnaire;
All participants
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The author has contributed to the development and writing of the paper.
NM, GE, CM, FH, JI, kc, VG, RP and contribute to the design and management of the study.
In addition, KB and HW contributed to the analysis.
All authors contributed to the drafting, review and revision of the manuscript and approved the final version.
Funding: The work of this paper is funded by a strategic grant from the strategic committee on sexual health and HIV Research of the Medical Research Council.
Competitive interests: No.