I've done a fair amount of research on the impacts of alcohol outlets on various measures of alcohol-related harm. That work has focused predominantly on violence, property damage, and crime generally. One thing I haven't looked at is the relationship with sexually transmitted diseases. That is for good reason. Crime is an acute outcome associated with drinking, and is measurable almost immediately. That distinguished crime from longer-term negative consequences of drinking such as liver cirrhosis, for example.
However, in-between those two extremes are some alcohol-related harms that we could refer to as medium-term harms. For example, the theoretical link between alcohol consumption and risky behaviour, including risky sex, seems clear. So, if having more alcohol outlets in a particular area is associated with greater alcohol consumption (following availability theory, as I discussed in this post earlier this week), then alcohol outlets should be positively associated with greater prevalence of sexually transmitted diseases. Sexually transmitted diseases do not become immediately apparent in the way that violence or property damage does, but they don't take years to manifest in the way that cirrhosis does.
There have only been a few studies on the relationship between alcohol outlets and sexually transmitted diseases. So, I was interested to read two studies recently related to this topic, which had been sitting on my to-be-read pile for some time. The first study was reported in this 2015 article by Molly Rosenberg (Harvard School of Public Health) and co-authors, published in the journal Sexually Transmitted Diseases (ungated NLM version here). They look at the relationship between alcohol outlets and Herpes Simplex Virus Type 2 (HSV-2) prevalence among young women (aged 13-21 years) in the Agincourt Health and Demographic Surveillance System site in South Africa. The Agincourt sample has predominantly been used as an HIV surveillance site, and there are dozens of studies based on this sample. However, they didn't look at HIV as an outcome in this study:
...because of the small number of prevalent infections at baseline and the likelihood that at least some of the cases were a result of perinatal, as opposed to sexual, transmission.
Fair enough. Perinatal transmission of HIV (transmission at or around the time of birth) has been a serious problem, but I guess it must be less of a problem for HSV-2. In their analysis, Rosenberg et al. essentially counted the number of alcohol outlets (both on-licence and off-licence combined) in each village, and related that number to HSV-2 prevalence for the 2533 young women in their sample. They found that:
Treating the alcohol outlet exposure numerically, for every 1-unit increase in number of alcohol outlets per village, the odds of prevalent HSV-2 infection increased 8% (odds ratio [OR; 95% CI], 1.08 (1.01–1.15]). The point estimate changed minimally after adjustment for village- and individual-level covariates (OR [95% CI], 1.11 (0.98–1.25]); however, this adjusted estimate was less precise.
Not only was it less precise, but it becomes statistically insignificant (barely), which they don't note. So, this doesn't provide strong evidence of a link between alcohol outlets and sexually transmitted diseases, although the evidence is suggestive. The problem is that the analysis essentially assumes that all young women in the same village have the same exposure to alcohol. This marks the number of outlets as an imperfect proxy for the real exposure variable, and suggests that the real effect might be larger. Again, this is suggestive evidence at best.
The second study was reported in this 2015 article by Matthew Rossheim (George Mason University), Dennis Thombs, and Sumihiro Suzuki (both University of North Texas), published in the journal Drug and Alcohol Dependence (sorry, I don't see an ungated version of this one online). This study did look at HIV as an outcome, relating zip-code-level HIV prevalence to the number of alcohol outlets (of different types) across 350 cities in the US. Perinatal transmission of HIV is not much of a problem in the US (certainly not compared to South Africa at the time that the Agincourt sample were born). Based on their data for a little over 1000 zip codes, Rossheim et al. found that:
...the presence of one additional on-premise alcohol outlet in a ZIP code was associated with an increase in HIV prevalence by 1.5% (rate ratio [RR] = 1.015). In contrast, more beer, wine, and liquor stores and gas stations with convenience stores were associated with lower HIV rates (RR = 0.981 and 0.990, respectively). Number of pharmacies and drug stores was not associated with HIV prevalence (p = 0.355).
On-premise outlets (predominantly bars and nightclubs) were associated with higher HIV prevalence, while liquor stores and gas stations were associated with lower HIV prevalence. Rossheim et al. don't have a good explanation for why, although they note a number of obvious limitations with their study. The literature on the impacts of alcohol outlets is littered with these sorts of inconsistent findings.
The real problem with a study like this is the time lapse between the alcohol consumption and the measured outcome variable. As I noted at the start of this post, with acute harm (like violence or property damage), the effect is immediately seen and can be measured, and likely occurred close to the location of alcohol consumption. With HIV prevalence, there is only a small chance that HIV was contracted as a result of activity within the local area. People move about over time, they 'interact' with people in many locations, and they can migrate from city to city. So, all we can say with this study is that people living with HIV tend to live in areas that have lots of bars and night clubs, and tend to live in areas that have fewer liquor stores and gas stations. Call this the gay-men-live-near-night-clubs effect, if you want to evoke a bunch of stereotypes. This effect is correlation, and it is difficult to say with any certainty if there is any causal relationship here.
Now, the Agincourt study has this problem as well, but the young women there probably still live in the same village they grew up in, so in that case the exposure to alcohol can be (imperfectly, as I noted above) proxied by the number of outlets in the village. And the symptoms of HSV-2 appear within a week, rather than weeks or months later as can be the case for HIV. So, moving about is less of an issue, although not eliminated entirely.
Anyway, these two studies are interesting, but they mainly highlight the problems with this broader literature. When we move beyond measuring acute harms associated with alcohol outlets, it isn't clear that the associations that are being measured are anything more than spurious correlation.
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