Research highlights – 30 September 2011

Research questions“Research highlights” is a weekly round-up of research papers appearing in the print BMJ. We start off with this week’s research questions, before providing more detail on some individual research papers and accompanying articles.

Should the UK switch to quadrivalent HPV vaccination?
Vaccination against human papillomavirus among teenage girls to prevent cervical cancer has been in the news recently, for all the wrong reasons. Minnesota congresswoman and US presidential republican candidate Michele Bachmann told NBC on 13 September that “[a mother] told me that her little daughter took that vaccine, and she suffered from mental retardation thereafter. It can have very dangerous side effects.” The American Academy of Pediatrics quickly retorted that “there is absolutely no scientific validity to this statement. Since the vaccine has been introduced, more than 35 million doses have been administered, and it has an excellent safety record” and bioethicist Arthur C Caplan from the University of Pennsylvania bet $10 000 (for charity) that Bachmann could not prove her claim.

In the UK at least 4.5 million doses of the bivalent vaccine have been given safely to girls aged 12-13. With the MHRA’s decision to choose the bivalent vaccine due for review, is it time to switch to the quadrivalent vaccine? Mark Jit and colleagues’ 2008 economic evaluation in the BMJ found the quadrivalent vaccine to be cost effective, but noted that “a bivalent vaccine with the same efficacy against human papillomavirus types 16 and 18 … may be as cost effective … although less effective as it does not prevent anogenital warts.” Now the same research team has modelled the latest data on effectiveness and safety. In a nuanced analysis with considerable uncertainty, the authors conclude that the quadrivalent vaccine is still more cost effective if the two are equally priced.

Blood donation by men who have sex with men
On September 8, the health ministers of England, Wales, and Scotland agreed to a change in the criteria that prevent men who have had sex with men from donating blood, from the current lifetime ban to a deferral period of one year after having sex with a man. In a timely qualitative study, P Grenfell and colleagues interviewed men who had sex with men about donation, finding that 11% had given blood despite being ineligible under the lifetime ban, and that a change in the rules was likely to be welcomed as “a step in the right direction.”

Some media responses to the announcement, however, declared that the new rules will remain discriminatory and would only slightly expand the pool of eligible donors. Matthew Sothern echoed these views, adding that the changes still fail to address risky behaviour among heterosexual donors. And later in the month, the Liberal Democrat party called for the policy to be updated further.

A more detailed questionnaire about individual behaviour for all potential donors has been proposed as a better way to determine risk, although editorialist Jay Brooks notes that this could be impractical. He also observes that the new criteria will need to be thoughtfully communicated, in light of the study’s finding that many men misunderstood the current donation policy—which was a major reason for non-compliance. To the dismay of gay rights supporters, the lifetime ban will continue to apply in Northern Ireland.

Chocolate and cardiometabolic disorders
After all the media attention this study received (just try Googling “chocolate” and “BMJ,” and you’ll soon get the gist), anything written here is likely to be superfluous. Suffice it to say that this meta-analysis by Adriana Buitrago-Lopez and colleagues included only seven observational studies with large variation in measurement, methods, and outcomes evaluated, so the results are tentative and show only association; however, that association is pretty impressive (high chocolate consumption linked with a decrease of a third in the risk of cardiometabolic disorders).

Certainly, Johan Mackenbach seems quite taken with the study in his linked editorial, and he summarises the situation nicely: “If this represents a causal effect it is substantial and comparable in magnitude to that of several other lifestyle related determinants of cardiovascular disease, such as serum lipids.”

One point that the paper mentions, but that many media stories overlooked, is that if chocolate ever does get “weaponised” to be a clinical treatment, the sugar and fat content will almost certainly need to be reduced—which is going to make it taste a lot less like chocolate and a lot more like medicine.