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Health News from NHS Choices

Constantly updated health news across a range of subjects.

NHS Choices News

  • Link between stillbirth and air pollution 'inconclusive'

    "Air pollution may raise risk of stillbirth and pregnant women should consider leaving cities, say scientists," The Daily Telegraph reports.

    This is somewhat radical advice given the study that prompted the headline produced no significant or conclusive results.

    Stillbirth is when a baby dies before birth, but after 24 weeks of pregnancy. There are about 3,600 stillbirths every year in the UK. It is a rare but devastating outcome, and it can be difficult to know why it's happened.

    Possible risk factors include infection during pregnancy, maternal smoking, maternal alcohol consumption, or having twins or multiple pregnancies. Often there is no obvious reason why a stillbirth happened.

    Scientists don't know whether air pollution is linked to stillbirth. This study was carried out to summarise all the research on the subject so far. But the results are still unclear.

    The pooled risks from the different studies showed a small increase in the chances of stillbirth if a woman lived in an area with raised pollution levels. But the increases in risk were so small that they could be down to chance.

    While air pollution is clearly not good news for anyone's health, and governments should do all they can to reduce it, this study does not prove that it causes stillbirth. Impractical and unrealistic advice that pregnant women should move out of cities does not help anyone.

    Where did the story come from?

    The study was carried out by researchers from the University of Oulu, Finland, and the University of Cape Coast, Ghana, and was funded by the University of Oulu. 

    It was published in the peer-reviewed journal Occupational Environmental Medicine on an open-access basis, so you can read it for free online.

    The Telegraph and the Daily Mail both led on comments from one of the researchers that it would be "wise advice" to tell a pregnant woman to move to a greener area, without discussing how realistic or practical such advice actually is for most mums-to-be.

    The news stories also fail to explain that the findings of this study were not statistically significant, meaning they could have been the result of pure chance.

    The Independent and the Daily Mirror give more cautious views of the research and include comments from other experts, which balance their reporting.

    What kind of research was this?

    This was a systematic review and meta-analysis of observational studies, including cohort studies and case control studies aiming to gather evidence to see whether there may be a link between air pollution and stillbirth.

    Systematic reviews are good ways of summarising the state of evidence on a topic, but they are only as good as the studies they include.

    There is always a possibility with observational studies that other confounding factors – such as the health and lifestyle of the individual woman – could bias the results.

    What did the research involve?

    Researchers searched for studies that looked at air pollution, including a wide range of air pollutants, and stillbirths.

    They included observational studies that gave information about mothers' estimated exposure to pollution (based on where they lived) and pregnancy outcomes.

    They then pooled the data for different types of pollutants to see whether any of them were linked to a raised risk of stillbirth.

    Most of the studies used data from air pollution monitoring stations and death certificates. Most balanced the results for confounding factors, such as the women's age and health.

    Some adjusted their results to take account of the effects of other types of pollution, although most did not. Some adjusted for factors like the time of year and weather, which can affect pollution concentrations.

    The researchers carried out a meta-analysis of the effect of each of six types of pollutant on the risk of stillbirth. The studies covered 11 types of pollutant, but there was not enough comparable information to do a meta-analysis on all types.

    What were the basic results?

    None of the six pollutants studied showed a clear risk of stillbirth. The pollutants included were:

    • sulphur dioxide
    • nitrogen dioxide
    • carbon monoxide
    • course particulate matter (PM10)
    • fine particulate matter (PM 2.5)
    • ozone

    All the pollutants were linked to an increased risk when levels were higher than average, but this raised risk was too small to be sure it was not down to chance – in other words, it was not statistically significant.

    In each case, the results' "95% confidence intervals" included the possibility that the raised pollution levels had no effect on risk of stillbirth.

    This was true for each of the pollutants studied at every stage of pregnancy. The results showed the effect of stage of pregnancy differed from one pollutant to another, so in some the possible risk was higher in the first trimester and in others it was higher in the third trimester.

    How did the researchers interpret the results?

    The researchers say they found "suggestive evidence" that air pollution is a risk factor for stillbirth.

    They say pregnant women "should be aware" of this risk, but that the main action required is by governments to reduce pollution levels.

    They do not state in the paper itself that pregnant women should move to the countryside.

    Conclusion

    Pregnancy can be an anxious time for women – well-meant but alarming advice about possible risks to your unborn baby is not always helpful.

    It's difficult to know what to make of a paper with inconclusive findings, like this one. As one expert says: "A reasonable headline for a press release on this work could have been 'Air pollution and stillbirth – we still don't know whether they are linked'."

    The quote comes from Professor Kevin Conway, professor of applied statistics at the Open University, who concludes: "I don't think these new findings should be a serious cause for concern for individual pregnant women – if there is an increased risk of stillbirth, this review indicates that the increase is pretty small."

    To put the risk into context, several of the pollutants studied were associated with a non-significant risk increase of around 2%. The non-significance means there's no evidence for a link, but even if there is one, it seems the risk increase from air pollution is likely to be very small.

    Compare to this the findings of a previous systematic review, which found that secondhand smoke exposure increased stillbirth risk by 23% – and this time it was a significant link.     

    However, Professor Conway and other experts agree that pollution and the potential risk of stillbirth are important topics to investigate, and future studies should be carried out to look at this area.

    While the study doesn't show that pollution definitely causes stillbirth, it doesn't rule out the possibility.

    One issue that needs to be addressed in future research is an accurate assessment of how much pollution individual women breathe in.

    The studies assessed women's pollution exposure based on where they lived in relation to the nearest air quality monitoring station.

    For some women, that was up to 25km away, so the levels monitored at the station may not reflect the quality of the air women were breathing.

    Other studies have shown that just moving one street back from a busy road can make a big difference to your exposure to pollution.

    We also don't know enough about the women's lives – where they worked, whether they travelled away from their homes, or what the air quality was like in their houses or workplaces.

    Another major problem with the study is that even if scientists did show a strong link to pollution, we don't know whether this might have been caused by other confounding factors.

    For example, people living in more polluted areas might have poorer health for other reasons, such as taking less exercise or having less money to spend on healthy food.

    Finding out whether air pollution might be a cause of stillbirth is not easy. It's good that scientists are doing this research and making an effort to find out about the effects of air pollution. So far, however, we don't have enough reliable information to know its effects for sure.

    The researchers' suggestion that pregnant women should consider moving to the countryside, as reported by the media, cannot be supported based on the evidence seen here. Aside from the impracticalities, moving house while pregnant could add unneeded stress during a pregnancy.

    The most effective steps you can take to reduce your risk of having a stillbirth are to avoid smoking and drinking and be cautious of sources of infections known to be harmful.  

    Links To The Headlines

    Air pollution may raise risk of stillbirth and pregnant women should consider leaving cities, say scientists. The Daily Telegraph, May 25 2016

    Pregnant women 'should consider moving to the countryside' because air pollution may raise the risk of stillbirth, doctors warn. Daily Mail, May 25 2016

    Air pollution could increase risk of stillbirth, research suggests. The Independent, May 25 2016

    Stillbirth risk increased by exposure to air pollution caused by car and industrial emissions, warn experts. Daily Mirror, May 24 2016

    Links To Science

    Siddika N, Balogun HA, Amegah A, et al. Prenatal ambient air pollution exposure and the risk of stillbirth: systematic review and meta-analysis of the empirical evidence. Occupational and Environmental Medicine. Published online May 24 2016



  • Proof opiates are useful for chronic back pain 'lacking'

    "Powerful painkillers doled out in their millions are ineffective against back pain," the Daily Mail reports.

    An Australian review found evidence for the effectiveness of opiate-based painkillers, such as tramadol and oxycodone, for chronic back pain was "lacking".

    The review pooled the findings of 20 trials investigating the safety and effects of opioid painkillers for non-specific or mechanical chronic lower back pain.

    This is back pain with no identified cause, such as a "slipped" disc or injury. This is a common, yet poorly understood, type of back pain that is often challenging to treat.

    The trials found opioids had a minimal effect on pain compared with an inactive placebo – about half the level that would be needed for a clinically meaningful effect.

    The rate of intolerance was also very high, with often half or more people experiencing side effects like nausea and constipation, and withdrawing from treatment as a result.

    The findings lend support to national guidelines for the management of non-specific lower back pain, which suggest it is inadvisable for a person to rely solely on painkillers.

    Self-management techniques, such as education, exercise programmes, manual therapy and sometimes psychological interventions, may deliver greater lasting benefits.

    If pain relief is needed, weaker painkillers, such as paracetamol, and anti-inflammatory drugs, such as ibuprofen, are advised initially, with strong opioids only used for a short period of time for severe pain.  

    If you are having trouble coping with chronic pain, contact your GP, who may be able to recommend additional treatments and services.

    Where did the story come from?

    The study was carried out by researchers from the George Institute for Global Health at the University of Sydney, and other institutions in Australia.

    Funding was provided by the Australian National Health and Medical Research Council.

    The review was published in the peer-reviewed journal JAMA Internal Medicine on an open-access basis, so it is free for you to read online.

    The Mail's reporting of the study was generally accurate, but the headline in the print version of its story – "Back pain drugs 'do more harm than good'" – is unsupported.

    The study only considered short-term side effects such as nausea and constipation, and not the longer-term problems addressed in the paper's reporting, like addiction and overdose.

    What kind of research was this?

    This systematic review and meta-analysis pooled the results of randomised controlled trials, aiming to see whether opioid painkillers such as codeine, tramadol and morphine are safe and effective for managing lower back pain.

    Although people with chronic lower back pain may often resort to the use of opioids because lesser painkillers are ineffective, the researchers say there has been no systematic study examining their effects and tolerability at different doses.

    A systematic review is the best way of gathering the available evidence to look at safety and effectiveness, but the strength of a review's findings are only as good as the studies it includes.

    What did the research involve?

    The researchers searched several literature databases to identify randomised controlled trials of opioid use in people with non-specific lower back pain.

    Sometimes called mechanical lower back pain, this is back pain where no specific cause can be identified, such as a herniated, or "slipped", disc, inflammatory conditions, infection, or cancer, for example.

    Trials were eligible if they compared an opioid with inactive placebo, or compared two different drugs or doses, and reported outcomes of pain, disability or adverse effects.

    There were no restrictions on the duration of back pain, painkiller use, use of other medications, or the presence of other illnesses. Two researchers reviewed and quality assessed studies, and extracted data.

    The trials included rated pain on visual or numerical scales (for example, rating pain from 0 to 100) and disability scores on questionnaires such as the Roland Morris Disability Questionnaire and Oswestry Disability Index.

    The researchers reported the mean difference in scores between the opioid and control groups. A difference of 10 points on a 100-point scale was a minimal difference required for any effect on pain, but a 20-point difference was considered a clinically meaningful effect.

    The researchers were mainly interested in short-term effects on pain relief. They also looked at the number of people who withdrew from the trial or were lost to follow-up as a result of adverse effects or lack of effect.    

    Twenty trials involving 7,295 people were identified, 17 of which compared opioids with placebo, while two compared opioids with each other.

    All the trials examined effects in the short term only – the maximum treatment and follow-up period was three months. The trials were generally high quality. 

    What were the basic results?

    The pooled results of 13 studies (3,419 people) found opioids had a minimal effect on pain – there was a mean 10.1 score difference between opioids and placebo (95% confidence interval [CI] 7.4 to 12.8 reduction).

    The difference when using single-ingredient opioids was 8.1, and 11.9 when using an opioid combined with another simple painkiller, like paracetamol.    

    There was limited data available for disability. Two studies found the combination of tramadol and paracetamol had no effect on disability compared with placebo, while another found no effect for morphine. However, the quality of evidence for these outcomes was said to be very low.

    The researchers looked at studies with a run-in period separately. This is where only those who responded favourably during the trial phase were actually randomised. Such trials therefore preferentially only include good responders.

    These results found increasing opioid dose was associated with better pain relief, but clinically meaningful effects on pain were still not seen at any of the doses evaluated.

    When looking at the two head-to-head trials directly comparing two opioids/doses, both trials found around a five-point score difference.

    The proportion of participants who withdrew was high in all trials – up to around 50% or greater withdrew.

    The main cause for withdrawal was lack of effect or adverse effects. More than half the people taking opioids experienced side effects such as nausea, constipation and headaches. 

    How did the researchers interpret the results?

    The researchers concluded: "For people with chronic low back pain who tolerate the medicine, opioid analgesics provide modest short-term pain relief, but the effect is not likely to be clinically important within guideline recommended doses." 

    Conclusion

    This systematic review found no evidence that opioids provide a meaningful effect on chronic non-specific lower back pain.

    Opioids are often used as a last resort for people who have not responded to other painkillers. But these results found opioids gave only half the size of the effect that would be needed to make a real difference – about a 10-point score difference, rather than 20.

    On the whole, the body of evidence was high quality. A large number of trials where identified, and most were multi-centre trials with good sample sizes carried out in the US, Canada, Australia and Europe. This means the findings should be representative of people with this condition in the UK.

    Most of the evidence compared the effect of opioids with placebo only, rather than any other active intervention.

    And 17 of the studies were funded by the pharmaceutical industry, giving uncertain potential for publication bias.

    However, in these cases, if anything, you would expect to see an overly favourable effect of opioids, which is not the case.  

    The extremely high dropout rate also cannot go unnoticed – 50% or greater in many studies.

    This may have contributed to the lack of effect seen, but also demonstrates the difficulty there is tolerating these strong painkillers. Many people experience debilitating side effects when taking them, such as nausea, vomiting and constipation.  

    Chronic non-specific lower back pain is an extremely common cause of disability in the UK. Perhaps overreliance on pain killers and anti-inflammatory drugs isn't the best answer.

    As the guideline body the National Institute for Health and Care Excellence (NICE) says, a key focus should be on helping people manage their condition themselves through education and information, exercise programmes, or manual therapy.

    Chronic non-specific pain can sometimes also have a psychological element, and interventions such as cognitive behavioural therapy can be helpful.

    NICE recommends regular paracetamol as the first-choice option for pain relief. If this is insufficient, they suggest moving to non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, or weak opioids, such as codeine, but being aware of the potential side effects of both.

    Stronger opioids, such as fentanyl or oxycodone, are only advised for short-term use for severe pain.     

    These recommendations, and the findings of this review, do not apply to people with identified causes of their back pain, such as inflammatory conditions, infections, cancer, or trauma. 

    If you have been taking opiate-based painkillers for some time and feel you no longer need or want to take them, you should talk to your GP. Stopping suddenly is not a good idea as this could trigger withdrawal symptoms.

    For more information, visit the NHS Choices guide to back pain.

    Links To The Headlines

    Powerful painkillers for back pain like morphine and tramadol are 'NOT effective and can be dangerous'. Daily Mail, May 23 2016

    Links To Science

    Shaheed CA, Maher CG, Williams KA, et al. Efficacy, Tolerability, and Dose-Dependent Effects of Opioid Analgesics for Low Back Pain. JAMA Internal Medicine. Published online May 23 2016



  • Report attacks official guidance on low-fat diets

    "Low-fat diet bad for your health and cutting back on meat, dairy and eggs a disastrous mistake," the Daily Mirror reports.

    That is the main message of a controversial report attacking official UK guidelines on diet and weight loss.

    The report suggests it doesn't matter how much saturated fat we eat, and doesn't recommend counting calories.

    Critics have pointed out there were no agreed criteria about what evidence would be considered in the report, leaving it open to accusations of cherry-picking.

    This means the report's authors may have promoted evidence supporting their argument while ignoring evidence they saw as unhelpful.

    Dr Mike Knapton, associate medical director at the British Heart Foundation (BHF), said: "This report is full of ideas and opinion.

    "However, it does not offer the robust and comprehensive review of evidence that would be required for the BHF, as the UK's largest heart research charity, to take it seriously."

     

    Who produced the report?

    The report was published by the Public Health Collaboration, a not-for-profit organisation described as being dedicated to informing the public and implementing healthy decisions.

    The report is said to follow decades of work and experience that founding and advisory board members have gathered through working with thousands of patients to improve their health.

    The listed advisory board members are named health professionals, including dietitians, GPs, a cardiologist, a diabetes specialist and a psychiatrist. They also list a number of patrons.

    It is unclear where Public Health Collaboration's funding comes from. Nor is it clear who wrote the report.

    No author or authors are named, and it does not appear to have been peer-reviewed by independent experts.

    The aim of the report is said to be to raise concerns about the government's current recommendations about healthy eating and weight loss, and also provide new evidence-based solutions to help people obtain healthy lifestyles and improve public health.   

     

    What does the report say?

    The report states the current prevalence of obesity in the UK is 25%, costing the economy £47 billion a year. 

    It summarises the recommendations of the current Eatwell Guide for healthy eating, saying it has three main concerns with this guidance:

    • the avoidance of foods because of their saturated fat content
    • the dietary reference value of no more than 35% total fat
    • the quality and quantity of carbohydrates

    Saturated fat

    The researchers say current recommendations given on NHS Choices are to opt for low-fat dairy options, as high saturated fat can increase the risk of heart disease.

    They highlight a large US cohort study from 2010 that concluded saturated fat intake was not associated with risk of cardiovascular disease.

    They quote several other observational studies that supported the notion that high-fat dairy was not linked to obesity or cardiovascular and diabetes risk.

    The researchers say: "In retrospect, there was never any strong evidence to recommend reducing total and saturated fat consumption, and in the 30 years since, the deteriorating health of the UK population suggests such advice may have been a dire mistake, however well intentioned."

    They consider that if people had been opting for foods in the natural form, rather than manufactured low-fat foods, we wouldn't have the obesity problem we do today.

    The Public Health Collaboration concludes the UK should stop recommending the avoidance of high saturated fat foods and focus on consuming food in its natural form – however much saturated fat it contains.

    No more than 35% total fat

    The authors question recommendations that too much fat in your diet raises the risk of heart disease and makes you overweight, saying this is not backed by scientific evidence.

    They reference a trial published this year, which found people on low-carb diets experienced more weight loss than people on low-fat diets, and say how recent US dietary guidelines have removed their previous 30% total fat limit and no longer place any restriction on fat.

    They conclude the UK should remove the recommendation to eat no more than 35% total calorie intake from fat and instead focus on the health benefits of eating food in its natural form – regardless of fat content.

    Quality and quantity of carbohydrates

    As the authors say, good blood glucose control is important to maintain health and reduce the risk of developing diabetes or pre-diabetes conditions.

    However, they say eating lots of foods that raise blood glucose and promote the release of insulin are factors likely to increase this risk – and high carbohydrates do just that.

    They discuss the glycaemic index (GI) of different foods, and say the UK's Eatwell Guide "illogically" recommends high-GI foods, advising people to "base meals on potatoes, bread, rice, pasta or other starchy carbohydrates".

    They suggest that such recommendations are behind the increase in rates of type 2 diabetes and obesity.

    The Public Health Collaboration concludes people should avoid foods that have a high carbohydrate density, and instead focus on food and drink that has a carb density of less than 25%. Such foods are usually in their natural form.

    "Real food" lifestyle

    The Collaboration sets out a new form of the Eatwell Guide called "The Real Food Lifestyle", which has a 50:50 split of fats and proteins against carbohydrates, but all food and drinks on the wheel are in their natural form.

    They emphasise carbs with a density less than 25% and a minimum of 1g protein per 1kg bodyweight per day.

    They also emphasise eating "real" foods that will fill you and avoiding processed "fake foods", which won't.

    For example, they recommend natural oils and butter, including coconut oil, ghee, lard and cold-pressed olive oil – the "fake" ones are rapeseed, sunflower and corn oil – and no juices or processed sugar products.

    If you were being critical you could argue that the division between “real food” and “fake food” is scientifically meaningless.
     

    What evidence is this based on?

    The report is presented in the form of a narrative, where individual pieces of evidence are cited as coming from particular studies. A list of references is then provided at the end.

    However, the report does not provide any information about how the authors identified and selected the research reviewed.

    As such, it is not possible to say this was a systematic review, and we cannot know for sure this is a balanced report that has reviewed all evidence relevant to diet and nutrition.

    The standard warnings about cherry-picking – evidence that is inconvenient may be ignored – apply.

    Also, without reviewing the individual studies referenced, it is not possible to appraise the quality and strength of this evidence. However, many are observational.

    There is potential for various sources of confounding and bias to influence associations between self-reported diet and health outcomes, such as inaccurate recall on food questionnaires or the potential influence of other unmeasured health and lifestyle factors.

    It can be difficult to know to what extent a particular outcome can be directly attributed to a particular food – or the absence of it.

    The report further says it "clearly and concisely provides an insight into the decades of work and experience that our founding members and advisory board have accumulated from working with thousands of patients".

    But it's not known what sort of experience or data from patients has contributed to informing this.  

    We also don't know, for example, whether the recommendations on fat and carbohydrate intake would be applicable to all stages in life, or whether there might be different advice for children.

    The report makes much of the fact that in spite of UK dietary guidelines, the number of people with obesity and type 2 diabetes has grown in recent decades. However, this does not prove that the guidelines are to blame. 

    What response has there been to the report?

    The report has attracted quite considerable criticism.

    Some professionals, such as the professor of diet and population health at the University of Oxford, note the lack of systematic review methods and accuse the report of potentially cherry-picking studies to support its viewpoint.

    Other studies presenting contradictory findings do not seem to have been included, they say.

    As a scientist from the University of Reading says: "As with any public health measure, it is important that any recommendations are based on solid evidence and take the wider implications of implementation into account. That doesn't seem to be the case in this instance."

    Professor Tom Sanders, emeritus professor of nutrition and dietetics at King's College London, says statements such as "fat doesn't make you fat", "saturated fat doesn't cause heart disease", and "avoid 'low fat' " are potentially harmful and could mislead the public.

    Other opinion is more mixed, with one professor saying the report has "good, bad and ugly elements in it". There are views that snacking and added sugar are to be avoided, but ideas that we should eat limitless fat and cut out sugar altogether are criticised.

    BBC news quotes Dr Alison Tedstone, Public Health England's chief nutritionist, who says: "In the face of all the evidence, calling for people to eat more fat, cut out carbs and ignore calories is irresponsible."

    She says thousands of scientific studies have been considered when making current UK health and nutrition recommendations.

    "It's a risk to the nation's health when potentially influential voices suggest people should eat a high-fat diet, especially saturated fat," she says.

    "Too much saturated fat in the diet increases the risk of raised cholesterol, a route to heart disease and possible death." 

    Links To The Headlines

    Low fat diet bad for your health and cutting back on meat, dairy and eggs a disastrous mistake. Daily Mirror, May 23 2016

    Public Health England: Advice to eat more fat 'irresponsible'. BBC News, May 23 2016

    Official advice on low-fat diet and cholesterol is wrong, says health charity. The Guardian, May 23 2016

    Now experts say low fat diets are BAD for you: Obesity charity claims you should stop counting calories and eat more healthy fats. Daily Mail, May 23 2016

    'Eat fat to get thin': Official diet advice is 'disastrous' for obesity fight, new report warns. The Daily Telegraph, May 23 2016

    Eating full fat foods 'can lower chance of obesity'. The Independent, May 23 2016

    Get fat to get fit: A diet rich in full fat dairy and meat can lower the chance of obesity, health charity claims. The Sun, May 23 2016

    Row over 'eat more fat' dietary advice. ITV News, May 22 2016



  • Healthier lifestyles 'could cut cancer death rates'

    "Half of all cancer deaths could be avoided if people simply adopted a healthier lifestyle," the Daily Mail reports.

    A new study adds to the weight of evidence that says combining simple lifestyle changes can dramatically cut cancer death rates.

    More than 100,000 health professionals from the US were asked to complete questionnaires about their lifestyle and cancer status every two years, and diet every four years.

    The researchers compared cancer rates between people with low- and high-risk lifestyle factors, and also compared rates in the low-risk group with the general white population in the US.

    They found a large number of cancer cases and deaths could be attributed to a high-risk lifestyle, such as an individual being overweight, smoking, drinking heavily, or being physically inactive.

    The researchers estimated between a quarter and a third of all cancer cases in this population group could be attributed to poor lifestyle factors.

    These findings are in agreement with past research and the understanding that a healthier lifestyle may reduce the risk of various types of cancer.

    But this study has limitations, including the population group, which only involved white American health professionals, and the possibility that the estimates are inaccurate. 

    The study would appear to confirm that any small lifestyle changes you can make, such as quitting smoking, could considerably reduce your risk of developing cancer. And the more of these small changes you can combine, the greater the effect.

    Read more about how lifestyle changes can help prevent cancer.

    Where did the story come from?

    The study was carried out by researchers from Harvard Medical School and was funded by the US National Institutes of Health.

    It was published in the peer-reviewed journal, JAMA Oncology.

    The Daily Mail reported on the study fairly accurately, but did not present any of its limitations.

    It's nice to see that the article included clear recommendations from the research team about how a person can reduce their risk of cancer.

    However, the headline figure of "half of all cancer deaths" seems a bit of a fudge, as the study presented a range of different results for specific cancer types.

    What kind of research was this?

    This prospective cohort study followed a large population group over time, and assessed the incidence of cancer and related deaths.

    The researchers looked at how these cancer outcomes were related to various lifestyle factors, and then estimated the proportion of cancers that could be attributed to these factors.

    The observational nature of this type of study means it is not able to prove causation, but it can find links and potential risk factors.

    This type of study has strengths in terms of being able to follow a large number of participants over a long period of time, but the number of people who become non-responsive to follow-up assessments may increase over the years.

    What did the research involve?

    The researchers recruited participants from two cohort studies:

    • The Nurses' Health Study – which started in 1976 and enrolled female nurses aged 30 to 55
    • The Health Professionals Follow-up Study – which started in 1986 and enrolled male health professionals aged 40 to 75

    Participants completed questionnaires about their medical history and lifestyle at the beginning of the study and every two years thereafter. Dietary information was collected every four years using a validated food frequency questionnaire.

    The researchers split the participants into two groups according to the level of health risk associated with their lifestyle.

    To be considered low risk, a participant had to meet the following requirements:

    • have never smoked or be a past smoker more than five years ago
    • drink no or a moderate amount of alcohol – no more than one drink a day for women and two for men
    • have a body mass index (BMI) of at least 18.5 and lower than 27.5
    • do at least 75 minutes of vigorous-intensity or 150 minutes of moderate-intensity aerobic physical activity a week

    If all of these requirements were not met, the participant would be considered high risk.

    The outcomes of interest were the incidence of total and major individual cancers and associated deaths. Cancer was self-reported in the questionnaires. Where a participant failed to respond, the National Death Index was used to identify deaths.

    The researchers compared the cancer rates between the low- and high-risk groups. They then compared cancer rates in the low-risk group with cancer rates in the general population using national surveillance data.

    They used this information to help them calculate population-attributable risk (PAR).

    This is an estimate of the proportion of all cancer cases that can be attributed to poor lifestyle factors, or the number of cancers that would not occur in a population if the risk factor – in this case, a high-risk lifestyle – was eliminated.

    For example, a PAR could be used to estimate how many people in a given population would not die of lung cancer if nobody in that population smoked.

    What were the basic results?

    A total of 135,910 people were included in the study (89,571 women and 46,339 men). The low-risk group contained 21% of all participants (12% women and 9% men) with the remaining 79% classed as high risk (54% women and 25% men).

    The incidence of cancer per 100,000 people was 463 for women and 283 for men in the low-risk groups, compared with 618 for women and 425 for men in the high-risk groups.

    From this, the researchers estimated that 25% of cancers in women and 33% of cancers in men could be attributed to high-risk lifestyle factors. For cancer-related deaths, 48% of cancer deaths in women and 44% of cancer deaths in men could be attributed to a high-risk lifestyle.

    For individual cancers, the proportion of cancers estimated to be caused by high-risk lifestyle factors were:

    • lung – 82% for women, 78% for men
    • bowel – 29% for women, 20% for men
    • pancreas – 30% for women, 29% for men
    • bladder – 36% for women, 44% for men

    Estimates were similar for cancer death, though there were additional associations for some other sites, including breast (12%), womb (49%), kidney (48% in men), and oral and throat (75% in women and 57% in men) cancers.

    The general US populations were at higher risk than the whole study population, meaning that the PARs for these cancers resulting from a poor lifestyle were even higher than the researchers' estimates – for example, the PAR for bowel cancer jumped to 50%. 

    How did the researchers interpret the results?

    The researchers concluded that, "In this cohort study of a portion of the US white population, about 20-40% of cancer cases and about half of cancer deaths can be potentially prevented through lifestyle modification.

    "These figures increased to 40-70% when assessed with regard to the population of US whites, and the observations are potentially applicable to broader segments of the US population." 

    Conclusion

    This prospective cohort study assessed the number of cancer cases and related deaths associated with poor lifestyle factors in a sample of US health professionals.

    As the findings demonstrate, a large number of cancer cases and deaths in both men and women can be attributed to a high-risk lifestyle, such as being overweight, smoking, drinking heavily, or being physically inactive.

    Worryingly, a poor lifestyle was estimated to account for an even greater number of cancers in the general population.

    These findings are in agreement with much research, which has found that a healthier lifestyle may reduce the risk of various cancers.

    The study has both strengths and limitations to consider. It contained a large number of participants and excluded types of cancer where incidence may be related to environmental factors rather than lifestyle, both adding strength to the findings.

    It did have limitations, however:

    • The use of questionnaires for collecting information is prone to bias, either by people reporting what they think they should be doing rather than what they are doing, or because of difficulty recalling information over a period of time.
    • Only medical professionals were included in the study. This group are potentially more health conscious, so may not be a good reflection of the whole population. This is supported by the fact that even the high-risk study group were healthier than the US population overall, and PAR estimates for cancer from poor lifestyle factors were higher in the general population.
    • Only including a white population means these findings may not necessarily apply to other ethnicities.
    • These results are only estimates: though informed by careful analysis of this population and their lifestyle factors and cancer rates, it's possible that the proportion of cancers attributed to poor lifestyle factors is inaccurate, particularly for wider populations.

    Despite these limitations, it is well known that unhealthy lifestyle factors could increase your risk of developing cancer, as well as various other health problems. Any small changes you can make to your lifestyle could considerably reduce your risk.

    Read more about how to prevent cancer.

    Links To The Headlines

    HALF of all cancer deaths could be avoided if we simply adopted a healthier lifestyle. Daily Mail, May 19 2016

    Links To Science

    Song M, Giovannucci E. Preventable Incidence and Mortality of Carcinoma Associated With Lifestyle Factors Among White Adults in the United States. JAMA Oncology. Published online May 19 2016



  • Review calls for global action to tackle antibiotic resistance crisis

    "Superbugs will kill someone every three seconds by 2050 unless the world acts now," BBC News reports.

    A review commissioned by the UK government says wide-ranging action is required at a global level to prevent a post-antibiotic future.

    The review panel, chaired by economist Jim O'Neill, warns that without global action, antibiotic resistance will become a "devastating problem" by 2050, responsible for an estimated 10 million deaths a year.

    Surgery could also carry a much higher risk of complications because of the possibility of infection.

    What is antibiotic resistance?

    Antibiotics are often used to treat bacterial infections and are a cornerstone of infectious disease care.

    However, bacteria evolve in response to their environment. Over time, they can develop mechanisms to survive a course of antibiotic treatment.

    This "resistance" to treatment starts as a random mutation in the bacteria's genetic code, or the transfer of small pieces of DNA between bacteria.

    If the mutations are favourable to them, they are more likely to survive treatment and be able to replicate, and are therefore more likely to pass on their resistant nature to future generations of bacteria.

    When taken correctly, antibiotics will kill most non-resistant bacteria, so these resistant strains can become the dominant strain of a bacterium. This means that when people become infected, existing treatments may be unable to stop the infections.

    What recommendations does the review make?

    The review makes 10 recommendations, outlined below.

    Launch a massive global public awareness campaign

    The issue of antibiotic resistance is still not fully appreciated, especially in the developing world, where antibiotics are often sold without prescription.

    The review estimates that a successful global campaign could be mounted for around $40 to $100 million a year, a fraction of the advertising costs for products like pet food or chocolate.

    Improve hygiene and prevent the spread of infection

    Improving access to clean water and sanitation, promoting best practice in hospital infection control, and simply encouraging people to wash their hands will all help prevent infection.

    Reduce unnecessary use of antibiotics in agriculture

    The US Food and Drug Administration estimates 70% of medically useful antibiotics are actually sold for use in animals.

    It argues that critically important antibiotics should be restricted from animal sales.

    Improve global surveillance of drug consumption and resistance

    Governments need to share data on antibiotic consumption and levels of resistance, and the biological reasons underpinning the two. Poorer countries should be given assistance in gathering data.

    Promote new rapid diagnostic tests to reduce unnecessary use of antibiotics

    Many antibiotics are prescribed in cases when a bacterial infection hasn't been confirmed, as a precaution. New types of tests could help prevent this.

    The review hopes that by 2020, in wealthy countries antibiotics would only be prescribed if a bacterial infection had been confirmed through testing.

    Promote the development and use of vaccines and alternatives

    Encouraging the take-up of existing vaccines, as well as providing incentives for the creation of new ones, should help reduce the demand for antibiotics.

    There also may be alternative interventions that can help prevent infections occurring.

    Improve the number, pay and recognition of people working in infectious diseases

    Infectious disease health professionals tend to be paid less than their peers working in other fields.

    A similar pattern can be seen in both private and public sector workers involved in infection research.

    Establish a Global Innovation Fund for early-stage and non-commercial research

    The review recommends that a Global Innovation Fund, endowed with $5 billion over the next five years, should be set up to fund "blue sky" research – research that may not have an immediate commercial application, but could lead to breakthroughs in the future.

    Better incentives to promote investment for new drugs and improve existing ones

    There is currently not a great deal of profit in antibiotic research, so pharmaceutical companies should be encouraged by meaningful incentives, such as a reward for bringing a new drug to market.

    Build a global coalition for real action

    Antibiotic resistance is a global problem, so it can only be tackled through global action. The review recommends that the G20 countries spearhead action via the United Nations. 

    Links To The Headlines

    Global antibiotics 'revolution' needed. BBC News, May 19 2016

    Blueprint To Tackle Growing Drug Resistance. Sky News, May 19 2016

    Antibiotics will stop working at a 'terrible human cost', major report warns. The Independent, May 19 2016

    No antibiotics unless doctor runs tests first: Superbugs tsar urges crackdown over fears infections 'will kill more than cancer' by 2050. Mail Online, May 19 2016

    Billion dollar rewards for new antibiotics called for to defeat catastrophic rise of superbugs. The Daily Telegraph, May 19 2016

    No antibiotics without a test, says report on rising antimicrobial resistance. The Guardian, May 19 2016

    Superbugs will kill 10m people a year without new antibiotics claims report. The Sun, May 19 2016