Wednesday December 19 2007
Drinking too much can damage more than your liver
A rise in unwanted pregnancies and sexually transmitted infections has been linked to binge drinking in women, the Daily Mail reported. More than “three-quarters of women taking part in a survey admitted they had unprotected sex because they were drunk”, the newspaper said.
BBC News also reported this story and came to the conclusion that condoms “should be given away in pubs, clubs and taxis to reduce the levels of unwanted pregnancies”. The authors of the research call for increases in the relative price of alcohol and restrictions on its availability.
The story is based on research that showed almost nine in 10 women who attended a busy sexual health clinic admitted binge drinking, at levels that equate to an average of two and a half bottles of wine in one sitting. Women who were then diagnosed with a sexually transmitted infection drank 40% more alcohol than those who were not infected. However, the design of this study means that it is not proof of a cause-and-effect link between alcohol-intake and sexual behaviour.
Where did the story come from?
K Standerwick of the School of Medicine in Southampton along with consultant nurse and doctor colleagues from Southampton and Portsmouth Hospitals carried out this research. It is not clear who funded the study. It was published in the medical publication: The International Journal of STD and AIDS.
What kind of scientific study was this?
This was a cross-sectional study in which the researchers gave a questionnaire to all consenting English-speaking patients who attended a large genitourinary medicine (GUM) clinic in the south of England between February 1 and April 5 2006. Of the 520 patients who completed the questionnaire, most (474) also agreed that the researchers could access their medical records for that day to determine whether they had a confirmed sexually transmitted infection.
The answers to the questionnaire was compared with the responses given in the General Household Survey; this is a continuous survey carried out by the Social Survey Division of the Office for National Statistics, which collects data on a range of topics such as employment, education, health and use of health services. It includes standard questions about people’s usual alcohol consumption over the past 12 months.
The researchers looked at the strength of any associations between alcohol intake and either sexually transmitted infections, number of sexual partners and unwanted pregnancy.
What were the results of the study?
The researchers say that the attendees at the GUM clinic binged heavily, drinking an average of 13 units on a usual night and 26 units on a “heavy” night. This was compared with an average of six units from matched questionnaire responses from the General Household Survey (GHS). In all, 86% of clinic attenders exceeded the UK government “binge drinking” level of six units, and 32% of subjects thought that alcohol played a role in their clinic attendance.
When attenders were asked about their alcohol intake before they had sex with a new partner, a total of 77% said they had been drinking before sex with a new partner and of these, 65% were usually or occasionally very drunk. Binge drinking was more common in those diagnosed with a bacterial sexually transmitted infection (STI) than those who were found not to have an STI. From the questionnaires completed by women, 19% reported an unwanted pregnancy and of these, 28% were drinking beforehand.
What interpretations did the researchers draw from these results?
The researchers conclude that a majority of attenders at a typical GUM clinic have been binge drinking to a significant extent, and a large proportion had been drinking before sex with a new partner.
What does the NHS Knowledge Service make of this study?
This study documents the behaviours of a group of GUM clinic attenders. The authors acknowledge that without using a “control” population of drinkers who did not develop sexually transmitted diseases as a comparison, they are unable to say to what extent heavy alcohol use increases the risk of catching a sexually transmitted disease, currently in the UK.
It is worth bearing in mind some features of this study when interpreting the results:
- The study was based on a questionnaire. The questions asked in the clinic to determine alcohol consumption were not the same as those used by the GHS (the survey used to assess levels of drinking in the general population) and the setting in which the questions were are asked may have determined the responses given. In general, to be strictly comparable, the same questions would need to have been asked by the same researchers in the same way. In particular, the GHS is not designed to assess levels of binge drinking.
- The quantity of alcohol drunk in a population does not fall neatly around an average intake, it follows a “skewed distribution”. This means that while some people may drink a lot, there are many more people that drink small amounts. Although alcohol consumption appears to be higher in the clinic attenders than in the sample from the GHS, it is the pattern of drinking that is different between the two groups and the significance of this difference is not addressed.
- It is not clear where some of the figures in the study come from. For example when the researchers say that 76% of people answered yes to the question “Have you had unprotected sex as a result of drinking?” it is not clear how many people answered this question.
In general, this study highlights a link between two topics of growing concern, the solution proposed by researchers and reported by the newspapers also deserves to be studied rigorously.
Sir Muir Gray adds...
I would have been more surprised had no link been shown.