Sexually Transmitted Diseases:
Incidence of Sexually Transmitted Diseases and HIV Infection in Men Who Have Sex With Men Related to Knowledge, Perceived Susceptibility, and Perceived Severity of Sexually Transmitted Diseases and HIV Infection: Dutch MSM–Cohort Study
van der Snoek, Eric M. MD, PhD*; de Wit, John B. F. MSc, PhD†; Götz, Hannelore M. MD, MSc‡; Mulder, Paul G. H. MSc, PhD§; Neumann, Martino H. A. MD, PhD*; van der Meijden, Willem I. MD, PhD*
From the * Department of Dermatology and Venereology, Erasmus MC, Rotterdam, The Netherlands; the †Department of Social and Organizational Psychology, Utrecht University, Utrecht, The Netherlands; the ‡Division of Infectious Disease Control, Municipal Health Service, Rotterdam Area, Rotterdam, The Netherlands; and the §Institute of Epidemiology and Biostatistics, Erasmus MC, Rotterdam, The Netherlands
Correspondence: Eric M. van der Snoek, MD, PhD, Erasmus MC, University Medical Centre Rotterdam, Department of Dermatology and Venereology, Dr. Molewaterplein 40, 3015 GD Rotterdam, The Netherlands. E-mail: email@example.com.
Received for publication May 10, 2005, and accepted July 27, 2005.
Background: This longitudinal study was conducted to investigate whether knowledge, perceived susceptibility, and perceived severity of HIV infection and sexually transmitted diseases (STDs) are associated with the incidence of STDs and new HIV infections among men who have sex with men (MSM).
Methods: A 3-year cohort study was conducted among 190 HIV-negative MSM. Data were collected on the incidence of STDs and new HIV infections, as well as on knowledge and perceived susceptibility to and perceived severity of HIV infection and STDs. Knowledge and perceptions were assessed in self-administered questionnaires.
Results: In the course of the 3-year study, six MSM (3.2%) HIV-seroconverted and 78 (41.1%) participants were diagnosed with at least one STD. MSM seemed to be better informed about HIV infection compared with STDs, and HIV infection was perceived as more severe than other STDs. In multivariable analyses, low perceived severity of HIV infection significantly (P = 0.025) predicted increased likelihood of infection with STDs or HIV, and the practice of anal intercourse was (marginally) associated with an increased risk of acquiring STDs or HIV (P = 0.052).
Conclusions: A high perceived severity of HIV infection seems to induce sexual behavior that protects against STDs and HIV infection. More research is needed to establish the specific behaviors by which perceived severity of STDs/HIV influences the incidence of STDs and HIV.
IN RECENT YEARS, SUBSTANTIAL increases in diagnosed infections with gonorrhea and early syphilis among men who have sex with men (MSM) have been reported from industrialized countries,1–5 whereas some studies also found increasing HIV infection rates among MSM.6–8 Increasing numbers of sexually transmitted infections are taken to indicate higher levels of sexual risk behavior and partly reflect more general changes in sexual practices. Notably, studies show that the prevalence of homosexual intercourse has increased,9,10 as did the practice of receptive anal intercourse,9 suggesting that higher numbers of men are now at risk. Furthermore, changes in transmission dynamics of HIV also affect sexual behavior, and it is hypothesized that the availability of effective antiretroviral treatment facilitates the replenishment of the pool of individuals willing to engage in risk-taking that was previously disproportionately depleted by AIDS-related morbidity and mortality.11
A range of psychosocial processes have in addition been suggested and explored to account for increased risk-taking among MSM and to delineate strategies for renewed HIV prevention. These include mechanisms that most likely exert their influence by increasing the availability of partners willing to engage in risk-taking11 such as sex-seeking on the Internet12,13 and increased opportunities for meeting sexual partners in saunas and back rooms.14 Processes such as optimism resulting from highly active antiretroviral therapy (HAART),15–18 HIV-prevention fatigue (i.e., MSM became habituated to the risk of HIV infection),19,20 and the use and abuse of drugs21 most likely affect volitional aspects of risk-taking and reduce men’s motivation to engage in safer sex.11 We propose that these disparate psychosocial processes may have in common that they promote or reflect a changed representation of the HIV epidemic that operates as a proximal determinant of high-risk sexual risk behavior in MSM.
This reasoning is supported by research testing the optimistic explanation of increased risk-taking among MSM that has found that a reduced perception of the health threat posed by HIV and a reduced perceived need for protective sexual behavior prospectively predicted an increase of unprotected anal sex with casual partners and increased the likelihood of incident infection with STD/HIV among HIV-negative MSM.22,23 Psychologic theory further suggests that motivational concerns can bias perceptions and beliefs,24 and following this process of motivated reasoning, we hypothesize that HIV-prevention fatigue and recreational drug use may also influence risk-taking through a (temporary) reduced perceived threat of HIV. Changed representations of the HIV epidemic in turn may make MSM more willing to look for sex, as in sex-on-premises venues or through the Internet, and can account for in-migration of new individuals who are willing to engage in high-risk behavior.11
Recent studies assessing the role of changed perceptions of the HIV epidemic as predictors of increased risk-taking among MSM differed substantially in the specific perceptions that were measured.16,17,22,25 Also, studies mostly relied on self-reported risk behaviors as the outcome variable, and often no theoretical framework was proposed to derive predictors, explain the pattern of findings, and guide translation into health promotion. Social–cognitive theories of health behavior provide such a framework by specifying sets of perceptions, evaluations, and beliefs that are proposed to determine individuals’ health-related behaviors and that represent targets for change through health education interventions.26–28 Following the health belief model,29,30 most theories assume that an individual needs to experience a sense of personal health threat before any protective action will be initiated. Relatedly, but not explicitly, addressed in the health belief model, when perceived health threat subsides, the motivation to engage in protective behavior most likely diminishes, which fits recent studies showing that reduced perceived threat of HIV results in uptake of unprotected intercourse and increased numbers of new STD and HIV infections among MSM.22,23
According to the health belief model, perceived health threat results from two specific perceptions: perceived susceptibility to the illness or condition and perceived severity of the condition. Among MSM, both perceived susceptibility to HIV infection and perceived severity of infection most likely have diminished in recent years,31 and the current study investigates the relevance of these core constructs of the health belief model in understanding the potential consequences of unprotected anal intercourse in a cohort of MSM in Rotterdam, The Netherlands. In particular, we studied whether among MSM perceived susceptibility to and severity of infection with HIV and infection with STDs, as well as knowledge of HIV infection and STDs, were associated with incident HIV infection and STDs. A specific aim was to assess the relative importance in terms of protection against infection of knowledge and perceptions regarding HIV versus STDs.
Materials and Methods
Study Population and Study Design
The study was conducted at the STD clinic of the Department of Dermatology and Venereology, Erasmus University Medical Center, Rotterdam, The Netherlands. From February 1999 to February 2000, we recruited 286 MSM to participate in the Rotterdam MSM–cohort study. Both HIV-positive and HIV-negative MSM were recruited by trained volunteers at gay meeting places like bars and saunas. Of all recruited males, 10 MSM (3.5%) were HIV-positive at entry. The way participants were recruited has been described in more detail elsewhere.32 Cohort participants were tested for STDs and HIV every 6 months. In case of STD symptoms in between two semiannual cohort visits, participants were urged to visit the STD clinic at short notice. At enrollment, all participants provided written informed consent, and the ethics committee of our hospital approved the protocol.
Inclusion criteria for the current study were: having had sex with at least one male partner in the preceding 12 months, being HIV-negative at enrollment, and having participated in at least five of six successive cohort visits. MSM who participated in five cohort visits but did not attend the last visit were excluded from the analyses because these men could not definitely be considered HIV-negative throughout the study period and STD-negative at their last study visit. Spontaneous clearance of any asymptomatic STD during the 6-month or 12-month intervals cannot be ruled out completely.
Data Collection and Questionnaires
At each visit, a medical history was taken, including self-reported STDs in the past 6 months. Also, demographic and sexual behavior information was collected, including ethnic background, age, educational level (defined as “low” with school attendance up to the age of approximately 16 years, “middle” with school attendance up to the age of approximately 18 years, or “high” indicated by a college degree or equivalent), sexual orientation, number of sexual partners during the previous 6 months, and having engaged in anal sex in the preceding 6 months. Participants further completed self-administered questionnaires on potential psychosocial predictors, including knowledge, perceived susceptibility, and perceived severity of HIV infection and STDs. These questionnaires were newly developed for this study.
To examine individuals’ perceived susceptibility to sexual acquisition of different STDs, including HIV, we included a total of 160 items (120 items concerning STDs; 40 items concerning HIV) that were scored on six-point rating scales (1 = “absolutely impossible”; 6 = “extremely high”) and an additional “don’t know” option. Assessment of the perceived likelihood of an infection related to sexual behavior was examined using the format “What do you think is the risk of becoming infected with ‘X’ as a consequence of?” followed by a specific sexual act. At the first and fourth visit, 40 items were included that measured perceived susceptibility to HIV, condylomata acuminata, genital herpes, and hepatitis A. At the second and fifth visits, 40 items were included on perceived susceptibility to HIV, gonorrhea, chlamydia, and hepatitis B. Participants were asked to self-report their perceived susceptibility to acquisition of these infections as a result of different sexual acts. Per visit, scores pertaining to STD items were averaged and a perceived susceptibility to STDs scale was constructed by calculating participants’ mean scores across visits. Likewise, a perceived susceptibility to HIV infection scale was constructed. In calculating scale scores, “don’t know” responses were not counted. Cronbach’s α showed that the perceived susceptibility scale had good internal consistency (α = 0.88).
To examine individuals’ perceived severity of personally acquiring different STDs, including HIV, we used a total of 42 items (36 items concerning STDs; six items concerning HIV) that were scored on four-point rating scales (1 = “absolutely not severe”; 4 = “extremely severe”) and a “don’t know” option. The perceived severity of an infection was examined using the format “How severe would you find if you were infected with … (e.g., HIV, gonorrhea, chlamydia)?” At all visits, seven items were included that measured perceived severity of HIV, syphilis, hepatitis B infection, gonorrhea, chlamydia, condylomata acuminata, and genital herpes. A perceived severity of STDs scale was constructed by averaging participants’ scores on the six relevant items per visit and next computing a mean score across the six different visits. A perceived severity of HIV infection scale was constructed by computing a mean score on the HIV items across the six different visits. Again, “don’t know” responses were not counted. Cronbach’s α showed that the perceived severity scale had good internal consistency (α = 0.81).
Knowledge of Sexually Transmitted Diseases and HIV
At the first, second, fourth, and fifth visits, 18 recurrent true/false/don’t know items assessed participants’ knowledge of STDs (12 items concerning chlamydia, gonorrhea, syphilis, and hepatitis A and B) and HIV (six items). These included statements like: “Receptive anal intercourse without intraanal ejaculation is safe for HIV infection,” “Oral–anal sexual contact (‘rimming’) can cause a hepatitis A infection,” and “Chlamydial infections at the anus only occur after unprotected anal intercourse.” At the third and sixth visits, another 10 true/false/don’t know items assessed STD knowledge only. These items comprised questions about genital herpes, condylomata acuminata, and again, chlamydia, gonorrhea, syphilis, and hepatitis A. A knowledge of STDs scale was constructed by counting each participant’s correct responses for each relevant item over all visits. Likewise, a knowledge of HIV infection scale was constructed. With respect to calculating knowledge scores, “don’t know” responses were considered incorrect responses. Cronbach’s α showed that the knowledge scale had good internal consistency (α = 0.82).
At each semiannual visit, participants underwent a standardized venereologic examination as described previously.32 In summary, blood samples were taken to be tested for HIV antibodies, syphilis, and hepatitis B. The examination also included testing for urethral, rectal, and oropharyngeal gonorrhea and urethral and rectal Chlamydia trachomatis infection by means of polymerase chain reaction technology. Genital herpes simplex virus infections and symptomatic human papillomavirus infections (condylomata acuminata) were not considered in this study because in most cases we did not know whether these infections were prevalent or incident.
Because of the small number of MSM who HIV-seroconverted, incidence of HIV was not considered separately and participants with any STD, including HIV, were compared with men without infection to establish differences in knowledge, perceived susceptibility, and perceived severity of STDs and HIV infection. A multivariable logistic regression model was built by including all variables with a univariable P value of less than 0.50. P values were calculated using the likelihood ratio test. For men who only participated in five cohort visits and consequently had missing values on one visit, missing scores for knowledge, perceived susceptibility, and perceived severity were imputed by the average of the available scores across the other five visits. All statistical analyses were performed with SPSS for Windows, version 11.0 (SPSS Inc., Chicago, IL).
Demographic Characteristics and Sexual Behavior
Between February 1999 and February 2000, a total of 286 MSM, with a median age of 39.5 years (range, 18–75 years; interquartile range, 33–48), were recruited into the cohort study. Of these participants, 266 (93.0%) were of Dutch descent. The educational level of 122 participants (42.7%) was “high” and was “middle” for 127 participants (44.4%). At entry into the study, 251 MSM (87.8%) stated to be exclusively homosexual. The median number of sex partners in the 6 months preceding the first visit was seven (range, 0–130). In that period, anal sex had been practiced by 183 men (64.0%), whereas 58 men (20.3%) stated to never have had anal sexual intercourse. An earlier diagnosis of STD was reported by 181 MSM (63.3%). Only one person (0.3%) worked as a male prostitute in the previous 6 months, and only 11 MSM (3.8%) declared to have had sex with a male prostitute in the previous 6 months. None of the participants had used any drugs intravenously. Characteristics of the study sample and epidemiologic as well as behavioral parameters as obtained at the first visit have been described previously.33
In total, 190 MSM (66.4% of the original 286 cohort recruits) could be included in the prospective study. Of the total 286 cohort recruits, 199 men participated in six and 17 men participated in five cohort visits, including the last visit. Of these 216 men, eight men were excluded because of HIV-positivity at enrollment. The data of 18 men had to be excluded because of administrative oversight and incomplete questionnaires. The 190 included MSM did not differ significantly from the full sample of cohort recruits in median age, ethnicity, educational level, sexual orientation, number of sexual partners, practicing anal sex, and history of STDs. However, among included MSM, significantly less STDs (P <0.0005) and HIV seroconversions (P <0.0005) occurred during the 3-year follow-up, compared with the excluded 96 men.
Sexually Transmitted Disease/HIV Prevalence
Table 1 summarizes the incidence of STDs and HIV infections (new diagnoses) in the 190 study participants for all six consecutive visits. Only data from the first visit can include prevalent STDs and HIV infections. Immune hepatitis B infection was only included in Table 1 when the tested individual was unaware of his immune status.
A total of 78 MSM (41.1%) were diagnosed with an STD or HIV-seroconverted during the 3-year follow-up. All these 78 MSM were diagnosed with an STD during at least one of maximum six visits. Chlamydial infections were most often detected. Early syphilis was seen in only one participant.
During the 3-year cohort follow-up, six of the 190 MSM (3.2%) HIV-seroconverted, all of whom were also diagnosed with an STD during at least one of the cohort visits, compared with 72 (39.1%) of 184 MSM who remained HIV-negative (P = 0.004). Four HIV-seroconverters (66.6%) had a concomitant STD during the visit at which HIV-seroconversion was detected. Three of these HIV-seroconverters had a concomitant rectal gonorrhea. No early syphilis was seen in MSM who seroconverted during the cohort study.
Knowledge, Perceived Susceptibility, and Perceived Severity
Knowledge of HIV infection was measured in all 190 MSM who on average scored 83% correct answers (range, 38–100%). On average, only 63% of the questions concerning knowledge of STDs was answered correctly (range, 25–96%), and MSM in this study were significantly better informed about HIV infection compared with STDs (P <0.0005).
Mean perceived susceptibility to HIV was moderately high (mean, 3.9; range, 1–6), as was mean perceived susceptibility to STD (mean, 3.9; range, 1–6; P = 0.70). Mean perceived severity of HIV was very high (mean, 3.9; range, 1–4). Mean perceived severity of STDs was significantly lower (mean, 2.9; range, 1–4), implying that participants on average perceived STDs as significantly less severe than HIV infection (P <0.0005).
Explaining Infection With HIV and Sexually Transmitted Diseases
Univariable analyses (Table 2) showed that perceived severity of HIV infection was associated with being diagnosed with an STD or HIV infection. MSM who indicated lower perceived severity of HIV infection had a higher likelihood of having experienced an STD or HIV-seroconversion (odds ratio [OR], 0.78; P = 0.022). Furthermore, MSM who had sexual contact with more partners also had a higher likelihood of acquiring an STD or HIV infection (OR, 1.01; P = 0.036). In addition, having had anal sex in the previous 6 months was marginally significantly associated with a higher likelihood of having had an STD or HIV-seroconversion (OR, 1.79; P = 0.059). No other univariable relations between infection with STDs or HIV and measures of knowledge, perceived susceptibility, and perceived severity were found at conventional levels of statistical significance (P <0.05).
In multivariable analyses, all predictors were entered that had univariable associations with infection with STD or HIV at P <0.50 (Table 3). Analyses showed a significant effect of perceived severity of HIV infection (OR, 0.77; P = 0.025). Lower perceived severity of HIV infection increased the likelihood of being diagnosed with an STD or HIV infection. Anal sex in the previous 6 months was associated with a higher likelihood of having had an STD or HIV-seroconversion (OR, 1.91; P = 0.052).
This study investigated whether, among MSM in Rotterdam, perceived susceptibility to STDs and HIV infection, perceived severity of infection with STDs and HIV, and knowledge of STDs and HIV infection were associated with the incidence of STDs and HIV infection. A specific question concerned whether perceived threat of HIV or perceived threat of STDs would be more important in promoting protection against infection. Multivariable analyses showed that high perceived severity of HIV infection significantly decreased the likelihood of infection with STDs and HIV. Furthermore, the risk of acquiring an STD or HIV infection was (marginally) significantly higher in MSM who practiced anal intercourse. Perceived susceptibility to STDs and HIV infection was not found to be related to infection with STDs or HIV, nor were knowledge of STDs and HIV infection and perceived severity of STDs.
It is of interest to find that a high perceived severity of HIV infection significantly decreased the likelihood of infection with STDs and HIV because this indicates that MSM with higher perceived threat of HIV may differ in their sexual behaviors in ways that reduce their likelihood of infection with STDs.34 The exact way in which perceived severity of HIV affects sexual behaviors could not be established in the current study, and this important issue remains to be addressed in future research. Practicing anal intercourse increased MSMs’ risk for infection with STDs and HIV, which presumably reflects the relation between risky sexual practices and likelihood of infection. Unfortunately, in this study, insufficient data were available regarding participants’ condom use to further test this reasoning. Nevertheless, we do know that between 20% and 30% of the MSM did not consistently use condoms while having anal sex, and avoiding or modifying unprotected receptive anal sex has also been identified as a behavior that significantly reduces risk of HIV infection.35–39
Our study has limitations that must be taken into account when interpreting the findings. First, “don’t know” responses on perceived susceptibility and perceived severity measurers were not counted in this study. Prevalence of these responses generally was low (2–9% across items), but it is possible that some bias was introduced. The direction of any potential bias is unclear, and “don’t know” responses given by MSM who were not motivated to engage in safer sex may have a different impact than similar responses given by MSM who were not familiar with certain STDs. Furthermore, it is important to note that cohort participants constitute a convenience sample of MSM from the Rotterdam region, and the sample presumably is not representative of any larger community of MSM neither in the city of Rotterdam nor in The Netherlands as a whole. However, despite this limitation, our findings do have importance. To the best of our knowledge, no other studies on the relation between perceptions of threat and incidence of STDs or HIV have been reported previously, whereas this type of study suggests an innovative approach for research that aims to contribute to an in-depth understanding of epidemiologic trends in STDs and HIV that is of relevance for health-promotion interventions. In particular, future research that addresses the exact way in which perceived severity of HIV infection promotes protective sexual behaviors should provide important information on psychosocial processes that codetermine disease outcomes. Such research can substantially contribute to the development of health-promotion programs aiming at prevention of new infections among MSM.
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