In countries where highly active antiretroviral therapy (HAART) is generally available to treat HIV/AIDS, both the infection rate of sexually transmitted diseases (STD) [1–6] and the amount of HIV-related sexual risk behaviour among homosexual men has increased in recent years [5–7]. In some cities, even the incidence of HIV among gay men has increased [8,9]. These findings raise concern about the future course of the HIV epidemic, and stress the need to find underlying reasons for the observed changes.
Research has found that risky sexual behaviour among homosexual men is associated with positive treatment beliefs that have arisen as a result of the introduction of HAART [10–16], possibly explaining part of the recent increases in risk behaviour and STD. Unfortunately, all studies investigating this association were based on cross-sectional data, making it impossible to determine causality between optimistic treatment beliefs and risky behaviour. Furthermore, in most studies, a combination of scores on statements measuring positive treatment beliefs was interpreted as optimism, but as suggested by Huebner and colleagues , prevention requires that we know and address different types of beliefs underlying any general optimism.
The aim of this study was to investigate prospectively the association between HAART-related beliefs and risky sexual behaviour among homosexual participants in the ongoing Amsterdam Cohort Study. First, we distinguished different types of HAART-related beliefs. Second, we characterized the men for whom a change-to-risk variable on an individual level (risk ‘i.e. no condom use': yes or no) was defined. Third, we studied the association between the different HAART-related beliefs and a change from no-risk to risky sexual behaviour on an individual level, to detect a possible causal relationship between treatment beliefs and a change to risky sexual behaviour.
Materials and methods
In 1984 the Municipal Health Service (MHS) in Amsterdam initiated the prospective Amsterdam Cohort Study among HIV-1-seronegative and HIV-1-seropositive homosexual men  to investigate epidemiological, behavioural and psychosocial questions in relation to HIV and AIDS. From 1995 onwards, only young participants were allowed to enter the study, resulting in the ongoing cohort among younger homosexual men. The inclusion criteria are: age younger than 31 years and having had at least one sexual encounter with a male partner during the 6 months before enrolment. The recruitment of participants is carried out by convenience sampling with advertisements placed in gay magazines and brochures distributed at the Amsterdam clinic for sexually transmitted diseases and social venues for homosexual men. Furthermore, every new participant is asked to recruit others among his acquaintances (`snowball’ method), and some participants were trained to recruit new participants in social venues.
Participants visit the Amsterdam MHS at 6-month intervals to complete self-administered questionnaires about epidemiological, behavioural and psychosocial issues related to HIV and AIDS.
Beliefs related to highly active antiretroviral therapy
Between September 1999 and May 2002 there were five data waves that included statements on HAART-related beliefs; 487 men participated in the cohort of younger homosexual men in this period, accounting for 1835 study visits.
The data waves included 17 statements concerning HAART-related beliefs. Statements were partly based on other studies [13,18] and were partly newly developed. Participants were asked to respond to each statement using a 7-point scale ranging from 1 ‘strongly disagree’ to 7 ‘strongly agree'. The reliability of the complete set of statements in measuring HIV optimism was adequate in the current sample (α = 0.75). However, there appeared to be several substantively distinct clusters of treatment beliefs.
Using principal components analysis with varimax rotation (assuming no correlation between the factors), we distinguished three clusters (see Appendix), each consisting of several related statements: perceiving less HIV/AIDS threat since HAART availability; perceiving less need for safe sex since HAART availability; and perceiving high effectiveness of HAART to cure HIV/AIDS. Their cumulative explained variance was 70.3%.
Reliability analysis was used to confirm the internal consistency of scales constructed on the basis of identified clusters, further described as HAART- related, or treatment beliefs. Treatment beliefs were subsequently defined for the five consecutive data waves.
The first treatment belief, perceiving less HIV/AIDS threat since the availability of HAART, explained 27.9% of the variance, and consisted of five related statements with a reliability (α) ranging from 0.73 to 0.87 for the five data waves. The second treatment belief, perceiving less need for safe sex since the availability of HAART, explained 24.9% of the variance, and consisted of three related statements with a reliability (α) ranging from 0.78 to 0.84. The third treatment belief, perceiving the high effectiveness of HAART to cure HIV/AIDS, explained 17.6% of the variance, and consisted of two related statements with a correlation (r) ranging from 0.70 to 0.75.
Scores on the treatment belief scales were calculated as the mean scores of the statements included, and ranged from 1 to 7. A higher score represents stronger agreement with the statements.
Unfortunately, we had to use a somewhat different set of statements on treatment beliefs in the second data wave, as a result of a temporary change in the questionnaire. Principal components analysis nvertheless resulted in the same three factors of treatment beliefs as in the other four data waves, only measured using fewer, but further identical statements (see Appendix).
For the definition of the change-to-risk variable we included men who tested HIV-negative by using enzyme-linked immunosorbent assays (ELISA; Abbott Laboratories, North Chicago, IL, USA; Vironostika Teknika, Organon, Oss/Boxtel, the Netherlands), who reported having had anal sex with casual partners in the preceding 6 months, and who participated in at least two data waves (N = 217 men, accounting for 780 visits). The median number of visits of these men was 3.0 [interquartile range (IQR) 2.0–4.0], the median follow-up time was 1.8 years (IQR 1–2), and 64 out of 217 men (29%) had participated in all five data waves.
In each of the five data waves, information was collected regarding receptive anal intercourse (RAI) and insertive anal intercourse (IAI) with casual partners in the preceding 6 months, as well as on condom use. Risky sexual behaviour was defined as not always having used condoms during anal intercourse with casual partners in the preceding 6 months, resulting in two dichotomous variables for each data wave: unprotected receptive anal intercourse (URAI 0 ‘no'; 1 ‘yes'), and unprotected insertive anal intercourse (UIAI 0 ‘no'; 1 ‘yes').
These variables enabled us to define the outcome variable for the present study: change-to-risk on an individual level, indicating whether a man changed from no-risk to risk or remained in the no-risk category between one data wave and the next (see Example 1). This dichotomous change-to-risk variable was categorized as 1 when a man changed his behaviour from no-risk (0 ‘protected anal intercourse') to risk (1 ‘unprotected anal intercourse') between the two data waves. The variable was categorized as 0 when a man practised protected anal intercourse in the two data waves.
The change-to-risk variable could be defined for each pair of subsequent data waves. When data on behaviour were missing for one of two measurements, the change-to-risk variable was defined as missing. Furthermore, a man could only be classified as having changed to risk or as having remained in the no-risk category when he reported protected sex for the first measurement of each pair. As a result, men could maximally change to risk behaviour twice during the total study period of five data waves.
The change-to-risk variable was defined for RAI and IAI separately, resulting in two separate outcome variables: change to URAI and change to UIAI.
For the outcome variable ‘change-to-risk on an individual level', 178 outcomes were defined for RAI and 181 outcomes for IAI. These involved 146 men, whose median age at first MHS visit was 29.8 years (IQR 26.7–32.7). Most men were of Dutch nationality (93.1%) and were highly educated (66.7%).
In addition to the three HAART-related beliefs, the five data waves provided information on socio-demographic and behavioural characteristics, including age, educational level (defined as low with school attendance up to the age of ± 16 years, as middle with school attendance up to the age of ± 18 years, and as high with a college degree or equivalent), nationality (Dutch, non-Dutch), and concurrent sexual behaviour reflecting complementary sexual risk. Concurrent IAI (`no IAI', ‘protected IAI', and ‘unprotected IAI') was used as a predictor of the change to URAI, and concurrent RAI (`no RAI', ‘protected RAI', and unprotected RAI') was used as a predictor of the change to UIAI.
To investigate the association between HAART-related beliefs and the change from no-risk to risky sexual behaviour on an individual level, univariate and multivariate logistic regression was used. The estimates and standard errors were corrected for intra-individual correlation between visits of the same individual by using generalized estimation equations , assuming an independent correlation matrix.
Treatment beliefs were included as continuous variables and were modelled using a time lag, because on each data wave the change-to-risk variable was linked to the treatment beliefs as measured on the preceding data wave.
Model building was performed using a backward stepwise procedure, starting with a multivariate model that included all variables with a univariate P value less than 0.1 and interaction terms between those variables, and by forcing age into the model.
Only statistically significant (P value < 0.05) variables and interaction terms were included in the final model. Confounding was defined as occurring when the inclusion of a variable in the multivariate model resulted in a change of more than 10% in the odds ratios of factors already present in the model. Two models were built separately for the change to URAI and the change to UIAI.
Characteristics (N = 146)
The median score on the three treatment beliefs was low, indicating that the majority of the 146 men in this study disagreed with the three beliefs: perceiving less HIV/AIDS threat (median 2.0; IQR 1.2–3.0), perceiving less need for safe sex (median 1.0; IQR 1.0–1.0), and perceiving high effectiveness of HAART in curing HIV/AIDS (median 1.50; IQR 1.00–2.50).
For RAI, 28 men changed to risk, and two of them changed to risk twice. For IAI, 49 men changed to risk, and only one man changed to risk twice. Twelve men concurrently changed to both URAI and UIAI in the same time period.
Prediction of change to unprotected receptive anal intercourse with casual partners
In univariate analyses (Table 1), only one treatment-belief factor was associated with a change to URAI; men who tended to perceive less HIV/AIDS threat since HAART were more likely to make this change. In addition, men who reported concurrent UIAI were also more likely to change to URAI compared with men who reported no or protected IAI.
In multivariate analyses, correcting for age, both variables remained independently associated and their effects became somewhat stronger (Table 1). Extending the final model with non-significant variables did not reveal any confounding factors, and no interactions among variables in the final model were found to be significant.
Prediction of change to unprotected insertive anal intercourse with casual partners
In contrast to findings regarding the change to URAI with casual partners, there was no univariate association between any of the HAART-related beliefs and a change to UIAI (Table 2). Only concurrent URAI with casual partners was found to be significantly associated with a change to UIAI. Controlling for age, men who reported concurrent URAI with casual partners were more likely to change to UIAI, compared with men who reported no or protected RAI with casual partners (Table 2). Extending the final model with non-significant variables revealed no confounders, nor was there a significant interaction between any of the variables.
To our knowledge, this study is the first to use longitudinal data in investigating the association between HAART-related beliefs and a change to unprotected anal intercourse in homosexual men. Results therefore contribute to a better understanding of a possible causal relationship between treatment beliefs and a change to unprotected anal intercourse on an individual level. Moreover, as different types of HAART-related beliefs were used as predictors, the study gives valuable and new information about which treatment beliefs in particular are important in predicting changes to unprotected anal intercourse.
In general, the homosexual men in this study seemed quite realistic about the effectiveness and consequences of HAART, as shown in other studies [10,11, 13,14,18]. Most men disagreed with the beliefs measuring less perceived threat of HIV/AIDS and less perceived need for safe sex since HAART. Furthermore, men did not endorse the belief that HAART is effective in curing HIV/AIDS.
Despite this realism, the study shows that men who incline towards agreement with perceiving less HIV/AIDS threat since HAART are more likely to change from protected to URAI. This finding is in concordance with findings from other studies, indicating that optimistic beliefs were associated with unprotected anal intercourse among homosexual men, and that those beliefs predominantly consisted of statements concerning the threat of HIV/AIDS [10,12–15]. Reduced perception of HIV/AIDS threat since HAART in particular thus appears to be important in understanding why men change to URAI.
Although causality is difficult to establish even with longitudinal data, the findings in this study are supportive of the hypothesis that perceiving less HIV/AIDS threat since HAART is a cause of the change to high-risk sexual behaviour. This suggests that decreased HIV/AIDS threat since HAART explains at least part of the increase in risk behaviour and STD seen at the population level since HAART became generally available [1–4,6]. The reported findings differ from those of Elford et al. , which caused them to conclude that HIV optimism is unlikely to explain the increase in high-risk sexual behaviour, and the findings of Huebner and Gerend , which suggested that beliefs about HAART may result from, rather than cause, increased risk behaviour. Although these conclusions might be valid, both studies were hampered by the fact that they were based on cross-sectional data.
As we have no absolute measurement of the participants’ level of perceived HIV/AIDS threat, it cannot be concluded that men with a low level of perceived HIV/AIDS threat are more likely to change to risky behaviour than men with a high level of perceived HIV/AIDS threat. It seems reasonable, however, to assume that those more inclined to agree with perceiving less HIV/AIDS threat since HAART do, in fact, have a lower level of perceived HIV/AIDS threat compared with men who do not agree.
Unfortunately, for the measurement of the treatment beliefs in the second data wave, fewer but further identical statements per factor were available, as a result of a temporary change in the questionnaire. However, the correlation among respective treatment-belief scales in the five data waves was moderate to high  and was comparable. The correlation ranged from 0.56 to 0.71 for perceived HIV/AIDS threat, from 0.27 to 0.68 for perceived need for safe sex, and from 0.31 to 0.58 for perceived effectiveness of HAART. This assured us that the treatment-belief scales from the second data wave could validly be included in the analyses.
Care should be taken in generalizing these findings to the total population of homosexual men, because our sample consisted predominantly of younger, HIV-negative, and highly educated homosexual men. Previous studies have found HIV-infected men to be somewhat more optimistic compared with HIV-negative homosexual men [7,10,11]. Likewise, there might also be differences between younger and older homosexual men. Younger homosexual men are probably less aware of the devastating effects of HIV and AIDS before the general availability of HAART, and therefore are possibly more vulnerable to perceiving less HIV/AIDS threat.
Implications for prevention
Despite these limitations, the results of this study have implications for preventative interventions. As the treatment of HIV infection continues to improve, and men perhaps live with the idea that an adequate vaccine against HIV infection might become a reality, the number of men who perceive less HIV/AIDS threat will probably increase. Given that this perception is associated with a change to URAI on an individual level, the number of men who engage in high-risk sexual behaviour will likewise increase. As a result, the incidence of STD such as syphilis, rectal gonorrhoea, and possibly also HIV, might further increase in the near future, especially if optimistic beliefs also lead to riskier sex between serodiscordant men. Behavioural risk reduction (notably, condom use during anal intercourse) therefore needs continued emphasis, especially in the light of the long-term side-effects of HAART, recent increases in HIV incidence, increasing transmission of drug-resistant HIV-1 strains [21,22], and the widespread unawareness of their HIV-positive status among homosexual men in Amsterdam. However, it remains to be determined whether addressing the reduced HIV/AIDS threat is an effective prevention strategy. As observed by Huebner and Gerend , HIV treatments have improved and HIV infectiousness has decreased since the introduction of HAART, giving men who perceive less HIV/AIDS threat strong arguments to do so, making this belief resistant to change.
In conclusion, the current study shed new light on a heavily debated and investigated issue. Homosexual men are quite realistic in their beliefs about the effectiveness of HAART, the need for condom use, and the perceived HIV/AIDS threat since HAART. However, this study provided evidence that a tendency towards perceiving less HIV/AIDS threat since HAART predicts a change to URAI on an individual level among younger, HIV-negative homosexual men who practice anal intercourse with casual partners. This finding supports the hypothesis of a causal relationship between decreased HIV/AIDS threat and a change to URAI on an individual level. The potential negative impact of a reduced perception of threat on the epidemic of HIV and other STD demands that we keep addressing the importance of risk reduction during anal intercourse with casual partners, and develop programmes tailored for different groups. As a change to URAI and UIAI with casual partners may involve different mechanisms, and variables other than perceiving less HIV/AIDS threat no doubt influence changes in sexual risk-taking, more research is needed to elucidate ongoing behaviour change processes.
The authors would like to thank Hélène van Bijnen, Dieuwke Ram and Nel Albrechts for their contribution in data collection, and Lucy Phillips for editing the final manuscript.
Sponsorship: This research has been funded by grant number 4014 from AIDS Fonds Netherlands. The Amsterdam Cohort studies are sponsored by the Netherlands Organisation for Health Research and Development (ZonMW), the Ministry of Health, Welfare and Sport (VWS), and AIDS Fonds Netherlands.
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Factors of highly active antiretroviral therapy-related beliefs and constituting statements identified among 487 younger ( 31 years) homosexual men in Amsterdam in the period September 1999–May 2002, Amsterdam Cohort Study, the Netherlands
Perceiving less HIV/AIDS threat since HAART (Crohnbach's alpha: 0.73–0.87)
I am less threatened by the idea of being HIV positive than I used to bea
I am less worried about HIV infection than I used to be
I think HIV/AIDS is less of a problem than it used to be
I think HIV/AIDS is a less serious threat than it used to be because of new HIV/AIDS treatmentsa
I am much less concerned about becoming HIV positive myself because of new HIV/AIDS treatmentsa
Perceiving less need for safe sex since HAART (Crohnbach's alpha: 0.78–0.84)
I think that condom use during sex is less necessary now that new HIV/AIDS treatments are availablea
I think that someone who is HIV positive now needs to care less about condom use
I think that the need for condom use is less than it used to be, because you can always start new treatments
Perceiving high effectiveness of HAART in curing HIV/AIDS (Pearson correlation coefficient: 0.70–0.75)
I think that someone who is HIV positive and uses new HIV/AIDS treatments can be cureda
I think that new HIV/AIDS treatments can eradicate the virus from your body
aIndicates the statements that were included in data wave 2. Data wave 2 included fewer, but further identical, statements as a result of a temporary change in the questionnaire.