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Welcome to the BMJ Open blog. BMJ Open is an open access journal, dedicated to publishing medical research from all disciplines and therapeutic areas.

Find out more about the journal here.

We will be updating the blog with news about the journal, highly accessed papers, press coverage, events and matters of interest in the open access and publishing world, and anything else that catches our eye.

What is ‘overdiagnosis’? Public meanings and misconceptions

28 Apr, 16 | by Ed Sucksmith

overdiagnosis pic 1

A recent study published in BMJ Open found less than 3% of the British public could define the meaning of overdiagnosis correctly. We talk to lead author Dr Alex Ghanouni about his research.

Stories about the ‘overdiagnosis’ of medical conditions regularly make the headlines. “GPs to trial new tests for asthma amid concerns about overdiagnosis” reported The Guardian in February, whilst in March The Telegraph declared “ADHD is vastly overdiagnosed and many children are just immature”. But what is meant by the term overdiagnosis and is it correctly understood? Some stories equate overdiagnosis with the proliferation of misdiagnoses or so-called ‘false-positives’ where a diagnostic test wrongly indicates that you have a medical condition. These meanings, however, are considered inaccurate by medical experts. They instead define it somewhat counter intuitively as the diagnosis of a disease which would never have become clinically apparent in a person’s lifetime. In other words, the disease is real but it does not cause the patient any harm, whether or not it has been identified through a medical test.

A research group led by Dr Jo Waller from University College London set out to assess the British public’s awareness and understanding of overdiagnosis. Why did Dr Waller and colleagues pursue this particular topic? “Our interest in overdiagnosis came primarily via the debate around its significance in breast cancer screening” explains Dr Alex Ghanouni, a member of the research team. Screening tests for breast cancer may lead to the identification of tumours that would not have presented clinically in the absence of the screening test. Overdiagnosis is therefore a significant concern because it could result in patients receiving unnecessary treatments as well as needless stress and anxiety that arise from receiving a diagnosis. “Knowing that the public often has only limited knowledge about the intricacies of screening tests, we speculated that the term has not reached public awareness, despite intense professional debate. We thought it important to assess this since it would limit people’s ability to consider it when deciding whether to take up a screening invitation.

Dr Waller’s team surveyed 390 adults from the UK aged 50-70 years of age. The survey asked participants if they had seen or heard of overdiagnosis and, if they had, to explain what the term meant. Results revealed that just 3 in 10 participants had encountered the term before, whilst less than 3% of all participants surveyed provided responses that were consistent with the accepted definition. A number of common misconceptions were identified, including equating overdiagnosis with both ‘misdiagnosis’ and ‘false-positive diagnosis’.

The study’s findings attracted a large audience when they were published in March. Were the authors surprised by the level of attention that their study received? “We were surprised in some respects”, says Dr Ghanouni, “In previous studies, we have found that overdiagnosis is something that few people understand intuitively and so we had some expectation that this would make the study less accessible to the general public. On the other hand, we were aware throughout the study that we were researching a topic where there were many strong views among medics and academics and so we did expect a degree of attention, at least among people working in related fields.

The survey results replicated previous studies that found low public knowledge of overdiagnosis in the UK and elsewhere. Dr Ghanouni and colleagues plan to further develop their research in this area. “This is an area of research that we are keen to take further and have in fact just had a paper published on a follow-up topic, namely, of information about overdiagnosis in breast screening that the public can read on the most prominent UK and Australian health websites. Some of our findings were quite striking; for example, we found that a markedly higher proportion of websites included relevant information compared to the last study to review information on the web, in 2002. This might indicate that the topic will gradually become something that more people know about.”


More on Overdiagnosis

For further information about overdiagnosis please see The BMJ’s ‘Too Much Medicine’ campaign, which aims to highlight and contribute to the evidence base on overdiagnosis and overtreatment. This includes a recent digital theme issue on overdiagnosis. The BMJ is also a partner in the upcoming Preventing Overdiagnosis conference that will be taking place on 20 – 22 September 2016 in Barcelona, Spain.

Ultra-processed foods, drinks marketed to children, and cannabis use in psychosis: Most read articles in March

8 Apr, 16 | by Emma Gray

Ultra-processed foods and added sugars, the content of drinks marketed to children, and cannabis use in first episode psychosis

File:Unhealthy snacks in cart.jpg

March was a busy month here at BMJ Open, with many new papers entering the Top 10 Most Read. In at number one this month is a popular paper which was press released and saw a lot of activity on Twitter: a cross-sectional study investigating the contribution of ultra-processed foods to the intake of added sugars in the USA. Boulton et al enter the list at number two with a much discussed survey of fruit juices to determine the sugar content of drinks marketed to children, which made national news, and Brown et al review the effectiveness of community pharmacy-delivered interventions for alcohol reduction, smoking cessation and weight management at number five. Investigating the association of cannabis use with hospital admission and antipsychotic treatment failure in patients with first episode psychosis, Patel et al come in at number five. Finally, at number nine we have an interesting analysis of systematic reviews by Elia et al which asks how authors of systematic reviews deal with research malpractice and misconduct in original studies.

Rank Author(s) Title
1 Martinez Steele et al. Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study
2 Boulton et al. How much sugar is hidden in drinks marketed to children? A survey of fruit juices, juice drinks and smoothies
3 Griffiths et al. Registered nurse, healthcare support worker, medical staffing levels and mortality in English hospital trusts: a cross-sectional study
4 Kristensen et al. The effect of statins on average survival in randomised trials, an analysis of end point postponement
5 Brown et al. Community pharmacy-delivered interventions for public health priorities: a systematic review of interventions for alcohol reduction, smoking cessation and weight management, including meta-analysis for smoking cessation
6 Patel et al. Association of cannabis use with hospital admission and antipsychotic treatment failure in first episode psychosis: an observational study
7 Shyangdan et al. SGLT-2 receptor inhibitors for treating patients with type 2 diabetes mellitus: a systematic review and network meta-analysis
8 Gattrell et al. Professional medical writing support and the quality of randomised controlled trial reporting: a cross-sectional study
9 Elia et al. How do authors of systematic reviews deal with research malpractice and misconduct in original studies? A cross-sectional analysis of systematic reviews and survey of their authors
10 Mekonnen et al. Effectiveness of pharmacist-led medication reconciliation programmes on clinical outcomes at hospital transitions: a systematic review and meta-analysis

Most read figures are based on pdf downloads and full text views. Abstract views are excluded.

Cannabis use in pregnancy linked to low birthweight and intensive care

5 Apr, 16 | by Emma Gray

As drug gains social acceptance, doctors and women need to be better informed, say researchers

Use of cannabis during pregnancy is linked to low birthweight and the need for intensive care, reveals an analysis of the available evidence, published in the online journal BMJ Open.

As cannabis becomes more socially acceptable, it’s important that prospective mums-to-be and clinicians are fully up to speed on the potential harms of using the drug during pregnancy, caution the researchers.

Cannabis “remains the drug of choice in developed and developing countries,” with up to 5% of 15-64 year olds around the world thought to use it, the researchers point out.

While it never used to be a major cause for concern, recent research has pointed to links between the drug and an increased risk of road traffic accidents, psychosis, HIV, hepatitis, infective endocarditis and TB. Less is known, however, about its possible effects on fetal growth and development.

The researchers carried out a comprehensive trawl of seven research databases for studies published up to 2014, looking at the effects of cannabis use during pregnancy on mother and baby up to six weeks after the birth.

Outcomes, such as anaemia in the mother, birthweight, baby’s length, need for neonatal intensive care, head circumference and early birth were all included in the review of 24 studies.

Analysis of the pooled data showed that mums- to-be who used cannabis were 36% more likely to have anaemia than women who didn’t use the drug.

Infants exposed to cannabis in the womb were 77% more likely to be under weight at birth and twice as likely to require intensive care as those whose mums had not used cannabis during their pregnancy.

The research in the analysis included observational studies, making it very difficult to draw firm conclusions about cause and effect. And the researchers were not able to extract data on whether any of the study participants used other illicit drugs or how much alcohol they drank—factors known to be associated with a higher risk of low birthweight and premature birth.

Nevertheless, they conclude: “There does appear to be negative consequences associated with in utero exposure to cannabis, including a decrease in birthweight and a need for placement in [intensive care].”

As the medical and social use of the drug “is rapidly becoming more acceptable in the USA and around the world,” understanding its effects on maternal and fetal health “should become a global priority,” they suggest.

Women and their doctors could do with more information on the possible harms of using the drug during pregnancy, they say.

Sugar content in fruit drinks marketed to kids “unacceptably high”

23 Mar, 16 | by Emma Gray

Almost half of products assessed contain entire daily recommended maximum intake

The sugar content of fruit drinks—including natural fruit juices and smoothies—is “unacceptably high,” with smoothies among the worst offenders, finds research published in the online journal BMJ Open.

Almost half the products assessed contained at least a child’s entire daily recommended maximum sugar intake of 19 g or almost five teaspoons, show the findings, which come ahead of the publication of the UK government’s childhood obesity strategy.

Increasing public awareness of the detrimental effect sugar sweetened drinks have on kids’ teeth and waistlines has prompted many parents to opt for seemingly healthier fruit juice and smoothie alternatives.

To assess the sugar content of fruit juice drinks, 100% natural juices, and smoothies marketed specifically to children, the researchers measured the quantity of ‘free’ sugars per 100 ml in 203 standard portion sizes (200 ml) of UK branded and supermarket own label products, using the pack labelling information provided.

‘Free’ sugars refer to sugars, such as glucose, fructose, sucrose, and table sugar, which are added by the manufacturer, and naturally occurring sugars in honey, syrups, fruit juices and fruit juice concentrates, but not the naturally occurring sugars found in whole fruits and vegetables, which the body metabolises differently and which act to curb energy intake.

The results highlighted wide variations in the amount of free sugars between different types of drink and within the same type of product.

The sugar content ranged from 0-16 g/100 ml, with the average 7 g/100 ml. But sugar content was significantly higher in pure fruit juices and smoothies.

Among the 158 fruit juice drinks analysed, the average sugar content was 5.6 g/100 ml, but rose to 10.7/100 ml among the 21 pure fruit juices tested, and to 13 g/100 ml among the 24 smoothies assessed.

Nevertheless, 85 juice drinks, which add up to more than 40% of the total sample of products, contained at least 19 g of free sugars—a child’s entire daily maximum recommended amount.

Almost 60% of all the products would get a red traffic light label—a coding system designed by the UK’s Food Standards Agency to help consumers identify high levels of fat, salt, and sugar in processed food and drink—the researchers point out.

Some 78 products contained non-calorific sweeteners, such as aspartame. Although safe, health experts believe that a reduction in the overall sweetness of products is required for children’s taste buds to become accustomed to less sugar in their diets, say the researchers.

Current dietary guidelines recommend that a serving of fruit juice/drink/smoothie should be no more than 150 ml, but only six of the products assessed matched this portion size.

Furthermore, the labels on all the products contained a reference intake, which is in line with European law. But this figure applies to an average sized adult woman who does an average amount of physical activity, so wholly inappropriate for children, the researchers emphasise.

They acknowledge that only products available in supermarkets were assessed, that new products constantly appear that may have lower sugar content, and that squashes and cordials were excluded because these are diluted to taste, making portion size comparison difficult.

But based on their findings, they make several recommendations:

  • Fruit juices/juice drinks/smoothies with a high free sugar content should not count as one of the UK government’s ‘5 a day’ recommendations, as is currently the case
  • Fruit should preferably be eaten whole, not as juice
  • Parents should dilute fruit juice with water or opt for unsweetened juices, and only allow these drinks during meals
  • Portion sizes should be limited to 150 ml/day
  • Manufacturers should stop adding unnecessary amounts of sugars, and therefore calories, to their fruit drink/juice/smoothie products—and if they can’t do this voluntarily, the government should step in with statutory regulations

Medical writing support, postnuclear disaster evacuation, and publication culture: Most read articles in February

10 Mar, 16 | by Emma Gray

Medical writing support and the quality of reporting, postnuclear disaster evacuation, and the current publication culture

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Once again, this month sees a selection of new papers entering the Top 10 Most Read list, alongside some old favourites. Returning to the top spot this month is Teschke et al‘s paper on bicycling injury hospitalisation rates, which continues to attract attention and generate discussion via our eLetters section. Entering at number two is a cross-sectional study examining the associations between mortality and registered nurse staffing in English hospital trusts, complete with podcast and press release. Gaining a significant amount of attention on Twitter, Gattrell et al examine the relationship between medical writing support and the quality of reporting of the results of randomised controlled trials at number three, and at number eight Nomura et al write about the long-term impact of postnuclear disaster evacuation on diabetes, hyperlipidaemia and hypertension. Concluding the list at number ten, Tijdink et al investigate the biomedical scientist’s perception of the prevailing publication culture.

Rank Author(s) Title
1 Teschke et al. Bicycling injury hospitalisation rates in Canadian jurisdictions: analyses examining associations with helmet legislation and mode share
2 Griffiths et al. Registered nurse, healthcare support worker, medical staffing levels and mortality in English hospital trusts: a cross-sectional study
3 Gattrell et al. Professional medical writing support and the quality of randomised controlled trial reporting: a cross-sectional study
4 Steffens et al. Social group memberships in retirement are associated with reduced risk of premature death: evidence from a longitudinal cohort study
5 Pitman et al. Bereavement by suicide as a risk factor for suicide attempt: a cross-sectional national UK-wide study of 3432 young bereaved adults
6 Marsh et al. Cost-effectiveness analysis of arthroscopic surgery compared with non-operative management for osteoarthritis of the knee
7 Greenhalgh et al. Virtual online consultations: advantages and limitations (VOCAL) study
8 Nomura et al. Postnuclear disaster evacuation and chronic health in adults in Fukushima, Japan: a long-term retrospective analysis
9 Kristensen et al. The effect of statins on average survival in randomised trials, an analysis of end point postponement
10 Tijdink et al. How do scientists perceive the current publication culture? A qualitative focus group interview study among Dutch biomedical researchers

Most read figures are based on pdf downloads and full text views. Abstract views are excluded.

‘Ultra-processed’ foods make up more than half of all calories in US diet

9 Mar, 16 | by Emma Gray

…And contribute 90 per cent of all dietary added sugar intake

‘Ultra-processed’ foods make up more than half of all calories consumed in the US diet, and contribute nearly 90% of all added sugar intake, finds research published in the online journal BMJ Open.

Ultra-processed foods are formulations of several ingredients. Besides salt, sugar, oils and fats, they include substances not generally used in cooking, such as flavourings, emulsifiers, and other additives designed to mimic the qualities of ‘real foods’.

Ultra-processed foods include mass produced soft drinks; sweet or savoury packaged snacks; confectionery and desserts; packaged baked goods; chicken/fish nuggets and other reconstituted meat products; instant noodles and soups.

To assess the contribution of ultra-processed foods to the intake of added sugars in the US diet, the researchers drew on dietary data invoving more than 9000 people from the 2009-10 National Health and Nutrition Examination Survey (NHANES), an ongoing nationally representative cross sectional survey of US civilians.

They looked at the average dietary content of added sugars and the proportion of people who consumed more than 10% of their total energy intake—the maximum recommended limit—from this source.

Ultra-processed foods made up over half of total calorie intake (just under 60%) and contributed almost 90% of energy intake from added sugars.

Added sugars represented 1 in every 5 calories in the average ultra-processed food product—far higher than the calorie content of added sugars in processed foods and in unprocessed or minimally processed foods andprocessed culinary ingredients, including table sugar, combined.

A strong linear association emerged between the dietary content of ultra-processed foods and the overall dietary intake of added sugars.

Furthermore, the proportion of people exceeding the recommended upper limit of 10% of energy from added sugars was far higher when ultra-processed food consumption was high, rising to more than 80% among those who ate the most ultra-processed foods.

Notably, only those Americans whose ultra-processed food consumption was within the lowest 20% had an average daily added sugar intake that fell below the maximum recommended limit.

Several leading health bodies, including the World Health Organization, the Canadian Heart and Stroke Foundation, the American Heart Association, and the US Dietary Guidelines Advisory Committee have concluded that excess added sugar intake increases the risk not only of weight gain, but also of obesity and diabetes, which are associated with a heightened risk of cardiovascular disease, and tooth decay.

Cutting back on the consumption of ultra-processed foods could be an effective way of curbing excessive added sugar intake in the US, conclude the researchers.

#BMJOpen5years: 2015 article highlight

29 Feb, 16 | by aaldcroft

We’ve been celebrating our fifth anniversary by highlighting some of the articles that have gained us attention, along with some that demonstrate our unique approach. 

Our final highlight, from 2015, comes from Mari Hysing, from Uni Research Health, and colleagues. Sleep and use of electronic devices in adolescence: results from a large population-based study was our most downloaded article in 2015, and has an Altmetric score of 319. According to the database Scopus, the article has already been cited 7 times.

Using data from nearly 10,000 adolescents, the study shows an association between screen time and quality of sleep. The longer a teen spends looking at a screen throughout the day, the worse the quality of sleep he or she is likely to have.

screen use

We asked Dr Hysing about the impact the article has made. She replied:

Research is quite a lonely exercise and knowing that others are interested in what we do gave us extra  motivation to continue.   It has been a great experience to publish this paper and  it was a very intense and fascinating week when the article got published.   

I have never experienced this level of media interest–by far–and this is probably a once in a lifetime experience.  Newspapers, TV channels and radio interviews from all over the world took most of my time that week.  Being able to reach out to so many with the research we do is a great experience. This is what we work for. 

Our study was on  the association between use of electronic devices and sleep. And I realized how many really struggle to get the sleep that they need, and how hard it is to log off and prioritize sleep. In addition to the interest from adolescents and parents, it seemed to be a big problem among the journalist that did the interviews. Maybe this is one reason why our article gained so much media attention?

#BMJOpen5years: 2014 article highlight

26 Feb, 16 | by aaldcroft

This week we’re celebrating our fifth anniversary by highlighting some of the articles that have gained us attention, along with some that demonstrate our unique approach. 

Cited 49 times in Web of Science, and with an Altmetric score of 306, our 2014 article highlight investigates the relationship between salt intake, blood pressure, stroke, and ischaemic heart disease mortality.

Using data from more than 31,500 people, Feng He and colleagues show that salt intake decreased by 15% in England from 2003-2011. During the same period, heart disease and stroke deaths fell by around 40%.

While several factors are likely at play, the results are encouraging. However, with 70% of the English population still consuming more than the recommended quantity of salt (6 g/day)–much of it coming from processed foods–further efforts to reduce salt consumption are needed.


#BMJOpen5years: 2013 article highlights

25 Feb, 16 | by aaldcroft

This week we’re celebrating our fifth anniversary by highlighting some of the articles that have gained us attention, along with some that demonstrate our unique approach. 

For 2013, we’d like to present two articles along with some key statistics.

Do healthier foods and diet patterns cost more than less healthy options? A systematic review and meta-analysis

Conclusions: This meta-analysis provides the best evidence until today of price differences of healthier vs less healthy foods/diet patterns, highlighting the challenges and opportunities for reducing financial barriers to healthy eating.

Key statistics:

  • Cited 41 times in Web of Science
  • Over 55,000 total full text and PDF downloads
  • Altmetric score of 708


A school-based education programme to reduce salt intake in children and their families (School-EduSalt): protocol of a cluster randomised controlled trial

BMJ Open strongly believes in the importance of publishing study protocols. Published in 2013, this protocol from China presents the methods for a cluster randomised control trial where children receive an educational intervention to reduce salt intake. Children are then asked to bring the salt reduction message home to educate their families.

Results were published in 2015 in The BMJ.

#BMJOpen5years: 2012 article highlight

24 Feb, 16 | by aaldcroft

Hypnotics’ association with mortality

This week we’re celebrating our fifth anniversary by highlighting some of the articles that have gained us attention, along with some that demonstrate our unique approach. 

Cited 66 times in Web of Science and with an Altmetric score of 480, “Hypnotics’ association with mortality or cancer: a matched cohort study” is certainly one of the most influential papers ever published in BMJ Open. Using a database including more than 10,000 patients, the study from Daniel Kripke and colleagues highlighted an association between sleeping pills and mortality.


We wrote to Dr Kripke to comment on the impact his article has had around the world:

“Publishing in BMJ Open was very satisfying, since the review was fast and fair, editing done well, and publication rapid and accessible.  The press release was remarkably effective.  In 50 years of research, I have never had an article covered so widely:  not only in European and North American media, but also in Japan, China, Thailand, even Myanmar, Bali, Yemen, and Ruanda.

“The important result, four years later, is at least 50 new studies of hypnotics risks, most of which mention our work.  This growing scientific focus is confirming and defining the risks of hypnotics more clearly.  I was particularly happy with Weich et al. that largely replicated our results in an even better-done study of a larger group, and Palmaro et al. that clarified how short-term hypnotics exposures have particularly high risk ratios.  New British and Taiwan studies have expanded the evidence for severe infection risks of hypnotics, a phenomenon that requires much more clinical and laboratory exploration.”

Also of note is the extensive post-publication discussion, along with extensive mentioning on Twitter that continues four years later.

Dr Kripke notes,

“In BMJ Open, the lively COMMENTS section response was very helpful in clarifying scientific critiques of our work, some of which I had the opportunity to rebut, and in disclosing the public emotional reactions that we need to understand for public health interventions.”