Research highlights 4 March 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.

Recurrent venous thromboembolism: are men at higher risk?
Although both sexes have the same risk of a first venous thromboembolism, men appear to be at higher risk than women of a repeat event. However, some large studies have failed to show this supposed association, possibly because of the confounding effects of age (men tended to be older in these studies) and use of hormone therapy by women (which is a reversible risk factor for stroke).

Whether a true link exists is of interest, because if men really are at increased risk, it might be worth keeping them on anticoagulant treatment indefinitely.

James Douketis and colleagues did a meta-analysis of individual patients’ data to ascertain the association between sex and recurrence of venous thromboembolism. They found that men had a 2.2-fold (95% confidence interval 1.7 to 2.8) higher risk of recurrent disease than women after “unprovoked” venous thromboembolism—that is, not associated with a major clinical risk factor—and the difference remained, albeit somewhat reduced, after controlling for use of hormone therapy by women. For venous thromboembolism that occurred in the presence of a major clinical risk factor (such as cancer or surgery) the risk of recurrence was the same in both sexes. The study also confirmed that the risk of recurrence was reversible in women who took hormone therapy.

Does this finding mean that doctors should treat men and women differently after a first event? In their editorial Frederick Spencer and Jeffrey Ginberg advise caution: “Lack of a clear cause for the observed association … casts doubt on its clinical relevance.” And they note that when this studies risk estimates are applied to the overall risk of recurrence of venous thromboembolism, the gap between the sexes is probably narrower.

Cannabis use and psychosis: which comes first?
Another of this week’s studies revisits a question last addressed here several years ago; it’s based on data from the early developmental stages of psychopathology (EDSP) study, a German prospective cohort study of which an earlier analysis, published in the BMJ in 2005, was among the most read BMJ research articles that year (doi:10.1136/bmj.38267.664086.63).

The 2005 article concluded that “Cannabis use moderately increases the risk of psychotic symptoms in young people but has a much stronger effect in those with evidence of predisposition for psychosis.” However, years later, whether the association between cannabis use and psychosis is a causal one is still unknown.

Analysing data from the 10-year follow-up wave of the EDSP study, Rebecca Kuepper and colleagues go some way further towards answering the question: they found that cannabis use preceded the onset of psychotic symptoms, and that continued use of the drug might affect the persistence of such symptoms.

Medical students: access denied?
Jonathan Mathers and colleagues looked at whether programmes developed to widen access to medical education in the UK have produced more diverse student populations, finding that graduate entry programmes had not greatly changed the socioeconomic profile of the medical student population, and that while foundation programmes increased the proportion of students from under-represented groups, the numbers entering these courses were small.

In an rapid response to the paper’s online publication, Nicholas Deakin, medical student and former chair of the BMA Medical Students Committee, welcomes the access schemes’ “small success stories” but thinks they are “firmly in the shadow of the looming trebling of tuition fees by the current government from £3290 up to a maximum of £9000 per year—despite lively student protests and strong representation from the BMA and others as to the dangers of such a move.
“The Sutton Trust has stated that fear of debt is a major factor for two thirds of students who choose not to pursue higher education. Such debt for medical students already stands at a predicted £37, 000 and is predicted to rise to £70, 000 … a death knell to widening access (” Student BMJ has more on this issue at

Survival with low lung function in cystic fibrosis
PM George and colleagues’ cohort study of patients in the adult cystic fibrosis unit of London’s Royal Brompton Hospital from 1990 to 2007 showed an improvement over the years in the survival of patients with lung function lower than the threshold generally accepted as indicating an increased risk of death within 2 years. A CME learning module accompanies the paper online (doi:10.1136/bmj.d1008).

Quality of chronic disease care for older people
Sunil Shah and colleagues compared the care for chronic diseases among older people in care homes with that of care in the community, within the UK Quality and Outcomes Framework pay for performance system. Their retrospective analysis suggests that care for chronic diseases included in QOF, measured by indicators suitable for vulnerable older people, is poorer for residents in care homes than for those in the community (doi:10.1136/bmj.d912).