Research highlights – 11 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.

Ethnicity and academic performance
Katharine Woolf and colleagues’ systematic review tackles a sensitive subject and comes to a controversial conclusion. The authors reviewed 23 quantitative studies that evaluated the performance of nearly 28,000 UK trained medical students and doctors, in both summative and formative assessments (including machine marked exams), and found that candidates from non-white ethnic groups did significantly less well than white candidates.

The full paper on is very detailed, showing how the authors did seven separate meta-analyses and took into account adjustments for confounding factors such as sex, first language, previous exam performance, and socioeconomic status. The association persisted and, despite limitations that included considerable heterogeneity in the primary studies and a mainly white versus non-white classification, the BMJ’s reviewers, editorial advisers, and editors agreed that the findings were robust enough.

The need to ensure effective and fair ways to train all doctors is a challenge for all of us, say the authors in their long and nuanced discussion of these findings.

Ultrasound and ulcers
In 2009, we published the VenUS II trial of larval therapy for leg ulcers (it didn’t improve healing) (BMJ 2009;338:b773). This week we publish VenUS III—different treatment, same negative result.

Compression bandaging is effective for most new leg ulcers, but larger and older ulcers have a poorer prognosis. VenUS III recruited patients with these hard to heal ulcers and looked at whether ultrasound therapy, in addition to standard care, might improve healing. Previous findings had suggested that it might, but the studies were not robust.
In this study, ultrasound seemed to have no effect on ulcer healing. The treatment was given in short weekly sessions of low dose, high frequency ultrasound for up to 12 weeks. One reviewer wondered whether a higher dose might have been more effective, but another agreed with the authors that the regimen tested was consistent with what was likely to be provided in primary care.

Leg ulceration is a chronic, recurring condition that affects 1.5–1.8% of adults in industrialised countries (with venous leg ulcers representing up to 84% of leg ulcers) and substantially affects health and quality of life. To learn more about management of venous leg ulcers, read a recent Clinical Review (BMJ 2010;341:c6045).

Benchmarking UK primary care research
The UK contributes 9% of the world’s research output for 4.5% of the world’s research expenditure, say Julie Glanville and colleagues, but is the work of world beating quality? With the new Research Excellence Framework (REF) ( about to replace the UK Research Assessment Exercise (RAE), the authors decided to benchmark the performance of research in their field, UK primary care.

Their bibliometric analysis looked at a 15% sample of the more than 82,000 primary care based studies that came from the UK, United States, Australia, Canada, Germany, and the Netherlands, and were indexed in Medline and Embase between 2001 and 2007. In every comparison the UK was in the top two countries for volume of papers and performance measures such as citation bangs for the buck/euro/pound.

The authors conclude that the RAE 2008 primary care panel was right to judge more than half its submissions as “internationally excellent or world leading.” Will the same apply in the REF 2014 assessment, with Chinese research improving by the day?

Cannabis and psychosis
Responses to Continued cannabis use and risk of incidence and persistence of psychotic symptoms (doi:10.1136/bmj.d738). This cohort study found that cannabis use was a risk factor for the development of incident psychotic symptoms.

“Elegant large-scale epidemiological studies such as this are able to clarify and here largely exclude the role of potential confounders, but this study in itself is concerned with cannabis-induced psychotic symptoms. Whether or not cannabis increases the risk for psychotic disorders, which it probably does, requires more clinically oriented studies using validated diagnostic instruments.” Sameer Jauhar and Stephen M Lawrie, Southern General Hospital, Glasgow.

 “If someone having smoked cannabis five times in their life is classed as a cannabis smoker, then probably a third of the population under 60 could be classed that way.” Rachel G Sagar, proofreader/tutor

“Cannabis is a psychoactive substance. It should be treated with respect and certainly not used by children. However, all these studies about psychosis are treated sensationally by the media.” Peter Reynolds, Legalise Cannabis Alliance

“The precursors to psychosis are surely anxiety attacks and paranoia, and these are as much a product of legal and social context as the person and the drugs themselves.” Darryl P Bickler, Drug Equality Alliance