Roughly one million individuals in the U.S. are infected with human immunodeficiency virus (HIV) and the rate is rising.1
Injection practices and risky sexual behaviors, such as anal and vaginal intercourse without a condom, among drug abusing populations have contributed to the growth and spread of HIV and other sexually transmitted diseases.2,3
In comparison with non-infected individuals, presence of other sexually transmitted Infections (STI) increases the risk of acquiring HIV by 200–500% when exposed to the virus through sexual contact. Additionally, if an HIV-infected individual is also infected with another STI, that person is more likely to transmit HIV through sexual contact than other HIV-infected persons.4
A number of studies have observed that sex under the influence of drugs or alcohol is associated with increase in sexual risk behavior.5–11
Approaches to studying the interplay between risky sexual behavior and substance use vary. There are two meta-analyses that detail the wide body of literature to date in regard to alcohol and condom use and alcohol and HIV infection.12,13
Much of the findings suggest an association between alcohol and sexual behavior. Although sexual risk behavior is often linked to substance use, the relationship is not clearly understood in regard to whether there is a correlative relationship or a causal relationship. Research on the link between substance use and sexual risk behavior has shown inconsistent findings.3,13
Some of this is due to the differences in methodological approaches.
Some studies use global association designs where general substance use habits are correlated with general sexual activity and condom use. In a typical global association study, participants provide information about the quantity and frequency of their recent substance use, as well as information about the number of times they engaged in specific sexual HIV-risk behaviors during the same reporting period.14
Other studies use situational association designs where a participant’s frequency of high-risk sexual behaviors is correlated with the participant’s frequency of engaging in sex while using substances.3,15
Situational association studies move beyond global association studies in that whether participants engaged in sexual acts while intoxicated is assessed and related to an index of sexual risk behavior.14
In event analysis, respondents are asked a number of questions about a specific sexual incident so as to ensure temporal contiguity of substance use and sexual behavior.3
Event analysis measures a participant’s substance use and safe/unsafe sexual behavior in a specific sexual incident so as to ensure temporal contiguity of substance use and sexual behavior. However, if a person is queried about two different recent events (e.g. under the influence and not under the influence sexual events) during the same assessment episode, the problem of attribution error may occur. Attribution theory is concerned with the ways in which people explain (or attribute) the behavior of others or themselves (self-attribution) with something else.16
This can refer to a situation where a respondent is asked about general sexual experiences in the recent past (some risky, some not) and asked why at times they behaved in a sexually risky manner. They may attribute the risky sexual behavior to substance use. Social desirability theory posits that a respondent will reply in a manner that will be viewed favorably by others.17
If it is socially more desirable to have safer sex but the respondent did not have safer sex, then the respondent may use the excuse that a substance is to blame for their behavior, i.e. “I only had unsafe sex because I was high.”
In order to obtain a causal relationship between substance use and risky sexual behaviors, Cooper et al.18
argue that the following conditions should be present. First, substance use must precede sexual activity. Second, substance-associated sexual behavior should be distinctively different from usual patterns of behavior. In other words, a causal association between risky sex and substance use can be made only if key risk behaviors are promoted (e.g., having sex with a partner who would normally be rejected) or key protective behaviors inhibited (e.g., failure to use a condom when one is usually used). By examining drinking/drugging and condom use in specific sexual encounters through the use of event analysis, one can target the role of substance use in influencing unprotected sex.
Traditional event analysis has limitations in that it does not eliminate the possibility of confounding factors such as personality characteristics.18
Someone who is predisposed to risky behavior may use substances and have risky sex more often either on a regular basis or during specific events, which cannot be teased out in event analysis of a single sexual event. However, if a respondent gives information on an event that include substance use and on another event that does not include substance use, it is possible to perform a within-participant analysis of substance using events and non substance using events and their sexual behavior risk.3
If the individual also reports on sexual events in which safe sex occurred and events in which risky sex occurred, then the possible link between risky sex and sex under the influence could be further elucidated by examining these double discordant (safe-risky sex/under the influence-not under the influence) events.
Breslow and colleagues proposed a conditional logistic model for estimating relative risk in matched case-control studies.19,20
Matched design doesn’t have separate independent samples of cases and controls. Our data is an example of a perfectly matched design, where three events are collected for each individual. A conditional logistic model is appropriate here since it allows within person analysis by conditioning on individuals, which yields an evaluation of the risk factors and fully controls the individual person characteristics that are difficult to control confounding factors in other designs.
The National Institute on Drug Abuse Clinical Trial Network protocol 0018 (The Real Men Are Safe trial) 21
provided a unique opportunity to examine the possible link between sex under the influence and risky sex. Analysis of baseline data from the trial indicated sex under the influence was associated with risky sexual behavior.11
Since only baseline data was utilized the approached only qualified as a “situational association” study. In the protocol participants were administer an audio computer assisted structured interview at three time points that included a detailed reporting of their most recent sexual event. This allowed for the possibility that some participants would report sex under the influence events and sex not under the influence across assessment time points. In addition some of these individual could report both sexually safe events and sexually risky events. By selecting cases that report discordant events on both of these two dimensions contributions attributed to individual differences such as personality can be held constant when comparing discordant events. In addition, potential attribution bias16
is minimized because the discordant events are reported on at separate time points 90 days apart and at no time are participants asked to compare these events on either the sexual risk or under the influence dimensions.
The objective of this paper is to examine whether support for a causative link can be established between sex under the influence and risky sex. Support for a causative link would be established if risky sex happens more frequently for under the influence events compared to not under the influence events for men who meet the criteria of describing multiple most recent sexual which were discordant on sex under the influence and risky sex dimensions across events.