Memorandum by John Imrie, Royal Free and
University College Medical School (SH 102)
1. BEHAVIOURAL
SURVEILLANCE AND
HIV EPIDEMIOLOGY
1.1 Background:
— Sexual behaviour, specifically the
rate of partner change and the types of sexual active that people
engage in, are essential factors in determining the transmission
of STI and HIV.
— Behavioural surveillance involves
monitoring and measuring patterns of sexual behaviour in populations
in order to understand changes in STI and HIV incidence and prevalence.
— Behavioural surveillance is important
in relation to prevention as it provides essential information
to determine what types of interventions are needed and the follow-up
data to gage their effectiveness.
1.2 Main sources of behavioural surveillance
data:
1. Routine reporting from health services
settings to the CDSC (eg KC-60).
2. Repeat cross-sectional and longitudinal
studies (eg NATSAL)
3. Ad hoc and one-off studies of sample populations
from the most affected groups (e.g. HIV positive gay men, African
ethnic minorities) (eg Mayisha Study of African Communities in
Camden and Islington).
Routine surveillance data collected by CDSC
is largely limited to demographic characteristics, likely route
of STI transmission/sexual orientation and HIV status. Limited
sexual behaviour, HIV status and HIV testing history data are
collected in some programmes.
Repeat cross-sectional studies—The frequency
with which these studies are repeated in part indicates the degree
to which changes in study populations' sexual behaviour is likely
to impact on trends in STI and HIV epidemiology.
Ad-hoc studies are used to study specific populations
provide detailed information but are usually of limited longer
term value because they only measure at one point in time and
have limited ability to detect change over time.
1.3 Current sources of behavioural surveillance
data according to population group:
1.3.1 General Population
— Routine data from CDSC (eg KC-60,
Survey of Prevalent HIV Disease Seen in Clinics (SOPHID), Unlinked
Anonymous Prevalence Monitoring Programme)
— Cross-sectional studies—National
Survey of Sexual Attitudes and Lifestyles (NATSAL).
1.3.2 Homosexually Active Men
— Routine data from CDSC (eg KC-60,
Survey of Prevalent HIV Disease Seen in Clinics (SOPHID), UA Prevalence
Monitoring Programme)
— Three ongoing behavioural surveys
(2 exclusively London focused, 1 nationally focused (ie England
and Wales) that includes London).
— One London surveys includes anonymous
saliva testing for HIV linked to self-completed questionnaires
— Several smaller studies examining
limited populations (eg men with diagnosed HIV infection attending
clinical services).
1.3.3 Sub-Saharan African Communities
— Routine data from CDSC (eg KC-60,
Survey of Prevalent HIV Disease Seen in Clinics (SOPHID), UA Prevalence
Monitoring Programme)
— Collection of ethnicity data in relation
to HIV testing and STI diagnosis has been reported since 1996.
— Included in wider cross-sectional
population surveys (ie NATSAL) however numbers recruited were
too small to make generalisable comments.
— No ongoing behavioural surveillance
studies in place.
1.3.4 Injecting drug users:
— UA Prevalence Monitoring Programme
routinely collects basic behavioural data specifically regarding
injecting practices and sharing of needles.
— Some qualitative studies have considered
the sexual behaviour of IDU in relation to HIV transmission
— No ongoing behavioural surveillance
studies in place, unlikely that they are needed.
2. TRENDS IN
RECENT BEHAVIOURAL
SURVEILLANCE STUDIES
2.1 Homosexually Active Men
There is increasing prevalence of HIV in this
group, partly due to better survival, but also due to continued
transmission. Over the passed six years researchers have observed
:
— Increases in new diagnoses of STI
in homosexually active men, and particularly in men with diagnosed
HIV infection and those of unknown serological status (see figure
1 and figure 2).
— No overall increase in the numbers
of sexual partnerships either regular or casual.
— Nationally, a reduction in the proportion
of men who report having engaged in anal intercourse (AI) in the
last year, but this is not the case in London.
— Among men who report engaging in
AI, an increase in the proportions who report routinely using
condoms.
— Equally, among men who report engaging
in AI, an increase in the proportions reporting having had unprotected
anal intercourse (UAI), with both regular and casual partners.
The proportion who report any AI in the last year ranges from
about 70-82 per cent, while the proportion who report having had
UAI exceeds 50 per cent in all of the surveys. There is considerable
variation according to survey, recruitment site, age and HIV status.
— An increase in the proportion of
men who report that they only engaged in sero-concordant (i.e.
both partners of same HIV status) unprotected anal sex (UAI).
— The greatest changes in the behaviours
carrying the greatest risk for transmission have been observed
among the youngest men, usually the under 25's and among men with
diagnosed HIV infection.
— The proportion of men who have ever
had an HIV test is subject to considerable regional and age group
variations. Nationally, among men aged less than 20 is less than
one-third have ever tested. In London approximately two-thirds
of men have ever tested compared to only about half in the North
West region and in Wales. There has been a significant in increase
in most areas, particularly in London, in the proportion who report
that their last HIV test was within the last year.
— More homosexually active men are
attending GUM services, however, the proportion who reported having
an STI diagnosed in the last year is also rising. There is no
uniform pattern nationally. In London, men with diagnosed HIV
infection were nearly twice as likely to have had an STI diagnosed
in the last year than either HIV negative or untested men.
— The prevalence of HIV in community
sample of gay men in London has not changed significantly in the
last two years. The community HIV prevalence in the Brighton pilot
study was 12 per cent and almost 8 per cent in Manchester. However
these prevalence figures should be interpreted with caution because
of the relatively small samples recruited in the pilot site cities.
3. THE IMPACT
OF ANTI-HIV
DRUGS ON
HIV RISK BEHAVIOURS
— Effective anti-HIV treatments have
had a major impact on the lives of people living with HIV.
— Many people now feel better, and
therefore feel more inclined to have sex.
— However the impact of anti-HIV drugs
on the observed changes in sexual behaviour, particularly homosexually
active men, is much less clear.
— Numerous studies internationally
have shown conflicting results about whether the availability
of effective treatments has lead to more reporting of higher risk
sexual behaviours.
— One UK study has shown that men on
treatments are less likely to report sexual behaviours that increase
the likelihood of onward transmission.
— Among all homosexually active men
other factors also seem to be involved, including: alcohol and
recreational drug use, psycho-social factors including depression
and low self-efficacy (ie belief in one's ability to perform a
specific behaviour (use a condom) in a given situation) and prevention
fatigue (ie tired of the same messages).
— In the case of men with diagnosed
HIV difficulties around disclosure and assumptions about HIV status
to sexual partners, previous negative sexual and lifetime experiences
(including early initiation of homosexual sex, having ever been
raped, or forced to non-consensual sex), ever having been involved
in commercial sex and experience of sexual and erectile dysfunction
appear to be associated with reporting having engaged in higher
risk sexual activities with casual partners and with sero-discordant
regular partners, and with a recent history if STI diagnosis.
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