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John Imrie a Department of
Sexually Transmitted Diseases, Royal Free and University College
Medical School, London WC1E 6AU, b Camden and Islington
Community Health Services NHS Trust, London WC1E 6AU
Correspondence to: J Imrie jimrie{at}gum.ucl.ac.uk
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Abstract |
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Objective:
To determine the effectiveness of a brief cognitive behavioural intervention in reducing the incidence of sexually transmitted infections among gay men.
Design:
Randomised controlled trial with 12 months' follow up.
Setting:
Sexual health clinic in London.
Participants:
343 gay men with an acute sexually
transmitted infection or who reported having had unprotected anal
intercourse in the past year.
Main outcome measures:
Number of new sexually
transmitted infections diagnosed during follow up and self reported
incidence of unprotected anal intercourse.
Results:
72% (361/499) of men invited to enter the study did so. 90% (308/343) of participants returned at least one
follow up questionnaire or re-attended the clinic and requested a check
up for sexually transmitted infections during follow up. At baseline,
37% (63/172) of the intervention group and 30% (50/166) of the
control group reported having had unprotected anal intercourse in the
past month. At 12 months, the proportions were 27% (31/114) and
32% ( 39/124) respectively (P=0.56). However, 31% (38/123) of
the intervention group and 21% (35/168) of controls had had at
least one new infection diagnosed at the clinic (adjusted odds ratio
1.66, 95% confidence interval 1.00 to 2.74). Considering only men who
requested a check up for sexually transmitted infections, the
proportion diagnosed with a new infection was 58% (53/91) for men in
the intervention group and 43% (35/81) for men in the control
group (adjusted odds ratio 1.84, 0.99 to 3.40). Using a regional
database that includes information from 23 sexual health clinics in
London, we determined that few participants had attended other sexual
health clinics.
Conclusions:
This behavioural intervention was
acceptable and feasible to deliver, but it did not reduce the risk of
acquiring a new sexually transmitted infection among these gay men at
high risk. Even carefully designed interventions should not be assumed to bring benefit. It is important to evaluate their effects in randomised trials with objective clinical end points.
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What is already known on this topic
What this study adds
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Introduction |
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Each year in the United Kingdom about 1400 homosexual men are
newly diagnosed as being infected with HIV; this figure has remained
comparatively stable for a decade.1 Gay men attending sexual health clinics in London report engaging in significantly more
high risk sexual behaviour than gay men surveyed in community settings.2 Effective behavioural interventions to reduce
sexual risk taking and infection with HIV and other sexually
transmitted diseases are clearly needed,3 and sexual
health clinics are an appropriate setting for such interventions. We
developed a small group intervention aimed at gay men, which draws on
several psychological models of behavioural change.4-6 We
evaluated its effects in a pragmatic randomised controlled trial using
clinical end points (new sexually acquired infections) as well as self reported changes in behaviour.
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Participants and methods |
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Participants
The study was approved by the University College London and
University College London Hospitals ethics committee. From September
1995 to November 1997, we invited homosexual men attending a sexual
health clinic in London to enter the trial if they presented with an
acute sexually transmitted infection, reported having had unprotected
anal intercourse with a partner of different HIV status in the past
year, or expressed concern about their sexual practices. Men were only
excluded if they were deemed by clinic staff to be unsuited for a group
education and counselling intervention. Participants were randomly
allocated using sealed opaque envelopes.
Data analysis
The sample size was calculated to detect a reduction of three
fifths in the proportion of men acquiring a new sexually transmitted
infection (from 20%, as estimated from recent clinic data, to 8%) in
12 months and a reduction of two fifths in the proportion reporting
having unprotected anal intercourse in the past month (from 50% to
30%). The aim was to recruit 346 men, assuming a statistical power of
at least 80% and 25% loss to follow up.
for example, does the participant
have confidence in his ability to use condoms properly) and uptake of
other interventions in the clinic or community. Five psychometric
measures were completed on the baseline questionnaire and each follow
up questionnaire. These were the situational self confidence
questionnaire, which measures self efficacy9; the Rosenberg self esteem questionnaire10; the readiness to
change questionnaire, which identifies an individual's position
relative to the model of stages of behavioural
change
4 11
; the sexual risk cognition questionnaire,
which measures beliefs associated with high risk sexual
behaviour12; and the HIV related attitudes questionnaire.13 Scores on the situational self confidence
questionnaire range from 0-10; higher scores suggest a higher level of
self confidence. Scores on the Rosenberg questionnaire range from
10-40; lower scores suggest higher self esteem. Scores on the
sexual risk cognition questionnaire range from 0-88; lower scores
suggest that a respondent has thought about sexual risk taking less
frequently. Scores on the component scales of the HIV attitudes
questionnaire range from 0-5; higher scores suggest more positive
attitudes towards taking control of one's risk of HIV.
Data from the questionnaires were double entered using EpiInfo software
and analysed using SPSS and Stata software. The primary analysis
included all participants who had been randomly allocated regardless of
whether they had received the intervention (intention to treat analysis).
For clinical end points, we compared the cumulative proportion of men
in each arm of the trial who had a new infection diagnosed at the
clinic during follow up. For sexual behaviour outcomes, we compared the
proportions reporting having had unprotected anal intercourse during
the past month and the past year. For psychological measures, we
analysed changes from baseline within the individual for each follow up
questionnaire. For unadjusted comparisons between the arms of the trial
we used the
2 test for binary data and t
tests or Mann-Whitney U tests for continuous data. For binary
outcomes, we adjusted for possible confounding factors at baseline
using logistic regression. We also compared those who had attended the
intervention with the controls (on-treatment analysis).
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Results |
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Baseline characteristics, attendance, and follow up
Altogether, 499 men were invited to enter the trial and 361 (72%)
agreed. Of these, 343 were randomly allocated (175 to the intervention
group and 168 to the control) and 18, who had a long term partner
in the trial, were assigned to the same arm as their boyfriend (11 in
the intervention group and 7 in the control) (fig 1). The 18 men
who had not been randomly allocated were excluded from the
analysis.
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Impact of the intervention
Self reported changes in sexual behaviour were modest but
generally there was more improvement in the intervention group (table
2): in this group the proportion of men engaging in unprotected anal
intercourse in the past month decreased from 37% (63/172) at
baseline to 24% (32/136) at 6 months and 27% (31/114) at 12 months. In the control group the proportion changed little: from 30%
(50/166) at baseline to 32% (44/139) at 6 months and 32%
(39/124) at 12 months. After adjusting for infections and unprotected anal intercourse at baseline, differences in these proportions between the arms of the trial were not significant (P=0.07
at 6 months and P=0.31 at 12 months). Findings were similar for the
proportions having unprotected anal intercourse in the past 12 months
(61% (106/174) in the intervention group and 63% (104/166)
in the control group at baseline compared with 50% (58/116) and 59%
(76/128) respectively at 12 months). Of those who reported at baseline
that they had had unprotected anal intercourse in the past month, 63%
(39/62) of the intervention group and 68% (34/50) of the control
group reported that the last episode was with a partner of unknown or
different HIV status. These proportions were 44% (14/32) and 65%
(28/43), respectively, at 6 months (P=0.11) and 48%
(15/31) and 46% (18/39) at 12 months
(P=0.9).
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Discussion |
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There have been comparatively few randomised trials of interventions aimed at changing sexual behaviour to prevent the transmission of HIV and other sexually transmitted infections.14 Even fewer trials have used the incidence of infection as an end point together with reported sexual behaviour.3 This is the first such trial in a population of gay men to measure both clinical and behavioural outcomes. 3 15 16 Analysis of the self reported behavioural outcomes suggested a weak beneficial effect, but analysis of the clinical end points indicated that the intervention was more likely to be harmful, although this was of borderline significance. However, the link between sexual behaviour and sexually transmitted infection is not simple. 7 17-19 Some infections, such as gonorrhoea, are usually acquired through penetrative sex, but others, such as herpes, can be acquired through low risk, non-penetrative sex. Furthermore, new viral infections can be hard to distinguish clinically from recurrent episodes. Thus, a broad definition of new infections may include some that were not acquired through high risk sex or that preceded the intervention, whereas a narrow definition may miss infections that were acquired through high risk sex. We tried to avoid this problem by using two definitions. When it is not possible to mask a participant's allocation, as in this study, it is particularly important to include clinical end points and not rely solely on self reported behavioural outcomes because these tend to overestimate benefit. 3 20
The higher risk of acquiring a sexually transmitted infection among participants in the intervention arm was unexpected, at odds with the data on sexual behaviour, and clearly a cause for concern. However, similar findings have been reported in other trials of behavioural interventions that used the clinical diagnosis of an infection as an end point.3 Three observations suggest that the increased risk of infection in our study is unlikely to be explained adequately by bias in the ascertainment of infection: screening rates at the clinic were similar in the two arms of the trial, and the proportion of men with a new infection was higher in the intervention group; matching using the regional database showed that we were unlikely to have missed many infections diagnosed elsewhere; and despite a comparatively low response rate, screening of urine samples suggested that the prevalence of asymptomatic infection in this population was low. Alternative explanations for the discrepancy between behavioural and clinical outcomes include bias due to loss to follow up or desirability bias, whereby participants in the intervention may have wished or felt obliged to report safer sexual behaviours. 17 20 21
The attenuation of differences between the two arms of the trial in the risk of becoming infected over time (as suggested by the extended review of the databases) supports the conclusion that the intervention may have led to an increased, albeit transient, risk of acquiring a new infection. Another possible explanation is that the intervention engendered in the participants a misplaced sense of confidence in their ability to negotiate high risk sexual situations, but this was not borne out by changes in the appropriate psychometric measures (table 4). We also considered the possibility that other interventions may have affected the outcome of the trial, but the uptake of other HIV prevention and counselling services was comparatively low and similar between the two arms.
Despite its promise and acceptability, the brief cognitive intervention
aimed at gay men at high risk of sexually transmitted infection did not
reduce their risk of acquiring new infections. Even carefully
formulated behavioural interventions should not be assumed to bring
benefit. It is important to evaluate their effects in randomised trials
using clinical end points wherever possible.
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Acknowledgments |
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Other members of the Behavioural Intervention in Gay Men Project Study Group are: Richard Barrett, Paul Bean, Rebecca Bickersteth, John Develin, Sandy Gale, Dr Sue Gessler, Debbie Holland, Angela McCadden, Kevin Miles, Nikki Penny, Ann Petruckevitch, Gillian Rhind, Kaye Stratton, and Dawn Whittaker. We thank all the study participants and the nurses, health advisers, doctors, and reception staff at the clinic who supported the study team. We owe particular thanks to the facilitators: Richard Barrett, Rebecca Bickersteth, Emma Callow, David Cornforth, Ruth Cracknell, Rebecca French, Jo Greenway, Mike Jones, Theresa Melrose, Kevin Miles, Simon Paragreen, Michael van Djikhuizen, and Simon Wright. We also thank Caroline Carder and Dr Geoffrey Ridgway, Clinical Microbiology Department, University College London Hospital; Dr Stephen Sutton, Imperial Cancer Research Fund Health Behaviour Unit, Royal Free and University College Medical School; Maria Griffin, Ali Judd, and Matthew Hickman of the Department of Social Science and Medicine, Imperial College School of Medicine, participating on behalf of the North Thames Genitourinary Medicine Clinical Directorate, London; and Dr John Parry and Julie Newham, Hepatitis and Retrovirus Laboratory, Central Public Health Laboratory, London.
Contributors: JI coordinated the study, participated in designing the questionnaires, coauthored the participants' workbook, and prepared the first draft of the paper. JMS was the principal investigator, designed the study, wrote the study protocol, and contributed substantively to the paper. FMC had the idea for the study and advised on designing the questionnaire and recruiting participants. SW developed the intervention and the training programme for facilitators, selected the psychometric outcome measures, and provided clinical supervision to the facilitators. AJPB assisted in developing the intervention and the training programme for facilitators, coauthored the participants' workbook, and provided clinical supervision to the facilitators. AJC oversaw the collection of data and performed the statistical analyses. LF managed the team of facilitators and advised on the content and delivery of the intervention. PDF advised on recruitment strategies and delivering the intervention, and facilitated the team's work in the clinic. AMJ advised on the study design. All authors reviewed successive drafts of the paper. JI and JMS are guarantors for the study.
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Footnotes |
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Funding: North Thames Regional Health Authority and the Camden and Islington Health Authority, London.
Competing interests: None declared.
A description of the cognitive
behavioural intervention appears on the BMJ's website
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References |
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(Accepted 22 March 2001)
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