19 Aug, 11 | by BMJ Group
“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.
- How does self refraction with adjustable spectacles compare with conventional methods for correcting vision in young people in rural China?
- Can the QThrombosis clinical risk prediction algorithm be used to estimate risk of venous thromboembolism in individual asymptomatic patients?
- Does pregnancy planning, time taken to conceive, or infertility treatment affect the subsequent child’s cognitive ability?
- What is the reoperation rate after colorectal resection in England, and can it be used to judge quality in colorectal surgery?
Low cost adjustable spectacles for refractive error in Chinese adolescents
Testing eyesight just isn’t feasible or affordable in many parts of the world, and about 153 million people worldwide are visually impaired simply for the lack of eye tests and glasses. So Professor Josh Silver invented the Adspecs adjustable spectacles, whose two fluid filled lenses can be deformed by attached pumps until the wearer can clearly see the letters on a vision chart and thus find out what lens power they need. This idea is so simple and appealing that it won the accolade of “Idea most likely to make the biggest impact on healthcare by 2020” at the BMJ’s session at the Healthcare Innovation Expo 2011 in London last March (BMJ 2011;342:d1998).
But are these spectacles a sufficiently accurate way to diagnose myopia? Yes, according to Mingzhi Zhang and colleagues’ cross sectional study in rural southern China, in which Professor Silver was a co-author. They studied 648 school students aged 12-18 who had uncorrected visual acuity ≤6/12 in either eye. Although the Adspecs didn’t perform as well as automated refraction with expensive devices, they allowed 97% of participants to achieve visual acuity ≥6/7.5, enough to see adequately in the classroom.
Editorialists Lisa Keay and David S Friedman note that, at $20 a pair, the Adspecs couldn’t be used as permanent glasses for people in many low income countries. And the frames don’t look great either. But they could certainly make testing affordable, and then allow people to pick the right pair of very cheap off the shelf glasses.
The BMJ’s editors were initially disappointed that this study wasn’t a randomised controlled trial but—with further explanation from the authors, very supportive reviewers, and the advice of a statistics editor—we became convinced that this was a useful and important study of diagnostic accuracy. One reviewer had seen Josh Silver’s adjustable spectacles back in the 1990s in Africa and was heartened to see a viable and valuable application for them, while the other reviewer said this work showed “thinking out of the box to address a serious problem that is now becoming epic in proportions.”
Video: Adaptive eyewear
A short film on bmj.com tells the story of Josh Silver’s adjustable spectacles and shows the device being put to work in Africa, where it’s hoped to bring corrective eyewear to those who need it for about £1 (€1.1; $1.6) without the need for eyecare professionals. It’s accompanied by videos showing the other ideas presented at the BMJ Innovation Expo conference: community led total sanitation, biobanks of health data, and use of social media to track epidemics.
Measuring quality of colorectal surgery by reoperation rates
Quality assessment of surgical performance first requires a suitable measure of clinically unexplained variation in surgical practice. Postoperative mortality is, of course, the big one, but it’s of limited use on its own since postoperative death is rare with elective surgery, and so we need measures of perioperative morbidity. Elaine Burns and colleagues now report on one potential measure—unplanned return to the operating theatre after colorectal surgery.
Using data from the Hospital Episode Statistics (HES) database for the whole of England, they show the feasibility of the approach and considerable variation in reoperation rates, implying plenty of scope for improvement among the hospital trusts and surgeons with the highest rates. They emphasise the need to verify the accuracy of the data before making any comparisons of institutions or surgeons, and the current dataset’s lack of relevant clinical information such as disease severity—but they obviously think the approach has potential.
In his linked editorial Morris Arden tends to agree, but he cautions that it is “much easier to study and report on quality measures than to improve quality” and that identifying a measure of surgical procedure is just the first step in the goal of improving surgical performance.
Risk of bias in the assessment of screening tools for depression
Brett Thombs and colleagues report in a systematic review that studies of the accuracy of screening tools for depression rarely exclude patients who already have a diagnosis or are receiving treatment, a potential bias that is not evaluated in systematic reviews and meta-analyses. This can result in inflated accuracy and estimates of the yield of new cases on which clinical practice and preventive care guidelines are often based, a problem that takes on greater importance as the rate of diagnosed and treated depression in the population increases (doi:10.1136/bmj.d4825).