The impact of the transmission dynamics of the HIV/AIDS epidemic on sexual behaviour: A new hypothesis to explain recent increases in risk taking-behaviour among men who have sex with men

https://doi.org/10.1016/j.mehy.2005.03.017Get rights and content

Summary

Increases in sexually transmitted infections and related high-risk behaviours have been reported among men who have sex with men (MSM) in industrialised countries when effective antiretroviral therapy against HIV infection has become widely available, in the mid-nineties. The reasons for these increases are not fully understood and often conflicting. Prevention fatigue, relapses to unsafe sex, as well as optimism toward the risk of developing AIDS among people living with HIV are not unique to the era of antiretroviral therapy (ART). This has led researchers to highlight the need to investigate other potential reasons that could explain the increase in high-risk taking following the ART introduction. We put forward the hypothesis that the change in the transmission dynamics of the HIV/AIDS epidemic before and after the introduction of ART has contributed to this change in high-risk behaviour.

It is suggested that a decline in sexual risk activities has occurred at the population-level following the initial spread of the HIV/AIDS epidemic because AIDS mortality and severe morbidity disproportionately depleted the pool of high-risk taking individuals. As a result, non-volitional changes may have occurred at the individual-level over time because the depletion of this pool of high-risk individuals made it more difficult for the remaining high-risk taking individuals to find partners to engage in risky sex with.

Following its introduction, ART has facilitated the differential replenishment of the pool of individuals willing to engage in high-risk taking behaviours because ART reduces AIDS mortality, and morbidity. Consequently, high-risk taking individuals who had previously reduced their level of risky sex non-volitionally (i.e., as a result of the reduced availability of high-risk partners) were able to resume their initial high-risk practices as the pool of high-risk taking individuals replenished over time. Thus, a fraction of the recently reported increase in high-risk sexual activities may be secondary to the fact that those MSM who were unable to engage in their desired high-risky sexual activities (because of reduced availability) are now able to revert to them as the availability of men willing to engage in risky sexual behaviours increases partly due to ART. Therefore, we suggest that a fraction of the changes in individual behaviour are non-volitional and can be explained by a change in “sexual partner availability” due to the transmission dynamics of HIV/AIDS before and after ART.

The hypothesis is formulated and explained using simple social network diagrams and the Theory of Planned Behaviour. We also discuss the implication of this hypothesis for HIV prevention.

Introduction

Increases in some STI and related high-risk behaviours for STI and HIV/AIDS have been reported since the mid-nineties among men who have sex with men (MSM) in industrialised countries [1], [2], [3], [4], [5], [6]. Reasons for the increases in risk behaviours are not entirely clear but prevention fatigue, lack of awareness among younger MSM and treatment optimism because ART became widely available have often been put forward as possible explanations [3], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]. However, most, if not all, of these reasons – including optimism toward the risk of developing AIDS among people living with HIV – have been identified in the early nineties and are therefore not unique to the ART era [17], [18], [19], [20], [21].

A recent meta-analytic review of 25 published studies on ART and sexual behaviour reported no significant overall effect between the use of ART or a reduced viral load and high-risk behaviours, but identified an overall positive association between positive beliefs about ART and high-risk behaviours [15]. The cross-sectional nature of the studies reviewed, however, makes it impossible to conclude on a causal relationship between optimism and high-risk behaviours. Optimism or beliefs may originate or intensify after someone engages in high-risk behaviours, acting as a posteriori self-justification [7]. Although some dimension of optimism was associated with high risk behaviour in cross sectional studies [15], other studies examining risk behaviours over time have shown that increases in risk are equally prevalent among the optimistic and the non-optimistic, thus questioning optimism as a driver of such change [9], [10]. In the only longitudinal study available to date [16], the only belief associated with an increase in unprotected sex, among HIV negative individuals was: ‘perceiving less HIV/AIDS threat’.

These conflicting results have led researchers to ask if the questions on optimism were properly formulated and to investigate if other reasons could explain the increase in high-risk taking behaviours following the wide scale availability of ART therapy [7], [9], [10], [12], [16]. The cornerstone of the present hypothesis is that the change in the dynamics of the HIV/AIDS epidemic before and after the introduction of ART has contributed to this change in high-risk taking behaviours.

Section snippets

Summary of the hypothesis: The number counts!

It is suggested that a decline in sexual risk activities has occurred at the population-level (cross-sectionally at the aggregate level) following the initial spread of the HIV/AIDS epidemic because AIDS mortality and severe morbidity disproportionately depleted the pool of high-risk taking individuals (i.e., individuals with several sexual partners or/and most likely to engage in unprotected sexual activities) [22], [23], [24], [25], [26]. As a result, non-volitional changes may have occurred

Volitional and non-volitional individual changes versus sexual environment changes

Potential changes in risk taking behaviours, as highlighted by mathematical modelling results [22], [23], are summarised and illustrated with simple social network diagrams.

According to mathematical modelling, changes in risk taking sexual behaviours occur at the population level, during the natural course of the HIV/AIDS epidemic, because AIDS related mortality or AIDS related illness (and cessation of sexual activity) disproportionately depletes the population of individuals with the riskiest

Theory of planned behaviour

Many social cognitive theories allow for extra-individual influences, even if such influences are infrequently assessed in interventions and even surveys. Although individually centred, the TPB is useful to our current work because it offers the possibility to assess extra-individual influences at several levels. The theory of planned behaviour (TPB, see Fig. 2(a)) is the dominant model for predicting and understanding health-related intentions and behaviour (see Armitage and Conner [35]; Godin

Discussion

We argue that “sexual partner availability” is an important determinant of sexual behaviour. According to this hypothesis changes in sexual partner availability caused by the HIV/AIDS epidemic and the wide scale use of ART could partly explain changes in sexual behaviour in the early eighties and mid-nineties among MSM both at the population-level and individual level. Indeed, mechanisms that affect availability such as the use of the internet to find sexual partners, has been associated with

Acknowledgements

M.C.B. thanks MRC for financial support and F.I.B thanks FIOCRUZ PAPES grant 250.250.122.

References (60)

  • D.A. Kault

    Modelling the effects of AIDS on gonorrhea epidemiology

    Math Comput Modell

    (1992)
  • I. Ajzen

    The theory of planned behavior

    Organ Behav Hum Dec

    (1991)
  • A.C. King et al.

    Theoretical approaches to the promotion of physical activity: forging a transdisciplinary paradigm

    Am J Prev Med

    (2002)
  • CDC. Increase in unsafe sex and rectal gonorrhea among men who have sex with men-San Francisco, California, 1994–1997....
  • K.K. Fox et al.

    Gonorrhea in the HIV era: a reversal in trends among men who have sex with men

    Am J Public Health

    (2001)
  • R.D. Stall et al.

    The gay ’90s: a review of research in the 1990s on sexual behavior and HIV risk among men who have sex with men

    AIDS

    (2000)
  • J. Elford et al.

    Trends in sexual behaviour among London homosexual men1998–2003: implications for HIV prevention and sexual health promotion

    Sex Transm Infect

    (2004)
  • I.G. Stolte et al.

    Risk behaviour and sexually transmitted diseases are on the rise in gay men but what is happening with HIV

    Curr Opin Infect Dis

    (2002)
  • I.G. Stolte et al.

    A summary report from Amsterdam: increase in sexually transmitted diseases and risky sexual behaviour among homosexual men in relation to the introduction of new anti-HIV drugs

    Euro Surveil

    (2002)
  • P. Van de Ven et al.

    HIV treatments optimism is associated with unprotected anal intercourse with regular and with casual partners among Australian gay and homosexually active men

    Int J STD AIDS

    (2002)
  • International Collaboration on HIV Optimism. HIV treatments optimism among gay men: an international perspective. JAIDS...
  • J. Elford et al.

    High risk sexual behaviour increases among London gay men between 1998 and 2001: what is the role of HIV Optimism?

    AIDS

    (2002)
  • E.G. Benotsch et al.

    Men who have met sex partners via the Internet: prevalence, predictors, and implications for HIV prevention

    Arch Sex Behav

    (2002)
  • S. Knox et al.

    Increasing realism among gay men in Sydney about HIV treatments: changes in attitude over time

    Intl J STD AIDS

    (2001)
  • M. Miller et al.

    Sexual behavior changes and protease inhibitor therapy

    SEROCO Study Group AIDS

    (2000)
  • T.P. Suarez et al.

    Influence of a partner’s HIV serostatus, use of highly active antiretroviral therapy, and viral load on perceptions of sexual risk behavior in a community sample of men who have sex with men

    J Acquir Immune Defic Syndr

    (2001)
  • J. Elford et al.

    Combination therapies for HIV and sexual risk behavior among gay men

    J Acquir Immune Defic Syndr

    (2000)
  • N. Crepaz et al.

    Highly active antiretroviral therapy and sexual risk behavior: a meta-analytic review

    JAMA

    (2004)
  • I.G. Stolte et al.

    Perceived viral load, but not actual HIV-1-RNA load, is associated with sexual risk behaviour among HIV-infected homosexual men

    AIDS

    (2004)
  • M.J.W. van de Laar et al.

    Declining gonorrhoea rates in The Netherlands, 1976–1988: consequences for the AIDS epidemic

    Genitourin Med

    (1990)
  • C.A. Carne et al.

    Prevalence of antibodies to human immunodeficiency virus, gonorrhoea rates, and changed sexual behaviour in homosexual men in London

    Lancet

    (1987)
  • A.G. Wardropper et al.

    Gonorrhoea as an indicator of altered sexual behaviour and as a surrogate marker of HIV concern: a 13-year analysis in Newcastle

    Int J STD AIDS

    (1995)
  • R.K. Lau et al.

    Trends in sexual behaviour in a cohort of homosexual men: a 7 year prospective study

    Int J STD AIDS

    (1992)
  • S.E. Taylor et al.

    Optimism, coping, psychological distress, and high-risk sexual behavior among men at risk for acquired immunodeficiency syndrome (AIDS)

    J Pers Soc Psychol

    (1992)
  • Boily M-C, Bastos FI, Hogben M, Godin G. The putative impact of HAART on individual sexual behavior. XIV international...
  • M.C. Boily et al.

    Changes in the transmission dynamics of the HIV epidemic after the wide-scale use of antiretroviral therapy could explain increases in sexually transmitted infections: results from mathematical models

    Sex Transm Dis

    (2004)
  • H.W. Chesson et al.

    AIDS mortality may have contributed to the decline in syphilis rates in the United-States in the 1990s

    Sex Transm Dis

    (2003)
  • S.M. Blower et al.

    Effect of differential mortality on risk behaviour change in cohort studies

    J Acquir Immune Defic Syndr

    (1993)
  • M. Fishbein et al.

    Belief, attitude, intention, and behavior: an introduction to theory and research

    (1975)
  • N.H. Dukers et al.

    Sexual risk behaviour relates to the virological and immunological improvements during highly active antiretroviral therapy in HIV-1 infection

    AIDS

    (2001)
  • Cited by (38)

    • What underpins the decline in syphilis in Southern and Eastern Africa? An exploratory ecological analysis

      2014, International Journal of Infectious Diseases
      Citation Excerpt :

      As observed in the USA, AIDS mortality could have been responsible for this effect in Southern and Eastern Africa. The effect of AIDS mortality could have been mediated via three pathways: (1) individuals most at risk of syphilis acquisition and transmission were removed from the population; (2) people living in areas with higher AIDS mortality may have been more likely to change their sexual behaviour;4,21 and (3) depletion of the pool of high-risk persons might have made it difficult for the remaining high-risk persons to find sufficient partners with whom to engage in risky sex.22 Another potential interpretation of our findings is that optimal STI treatment was more effectively provided in countries with higher peak HIV prevalence estimates.

    • Could there have been substantial declines in sexual risk behavior across sub-Saharan Africa in the mid-1990s?

      2014, Epidemics
      Citation Excerpt :

      Uganda provides an example where rapid reductions in sexual risk behavior appear to have led to a dramatic drop in HIV prevalence (Kamali et al., 2000; Kilian et al., 1999; Low-Beer and Stoneburner, 2003; Stoneburner and Low-Beer, 2004). Other studies in other countries have also suggested that reductions in sexual risk behavior have led to declines in HIV prevalence such as in Zimbabwe, Kenya, and Malawi (Bello et al., 2011; Boily et al., 2005; Gregson et al., 2010; Hallett et al., 2006, 2009; Kilian et al., 1999; Low-Beer and Stoneburner, 2003; Walker et al., 2008). It is not clear, however, whether such changes have occurred widely across SSA.

    • Pre-Exposure Prophylaxis: An Ethical Discussion

      2013, Journal of the Association of Nurses in AIDS Care
    View all citing articles on Scopus
    View full text