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|Fri, 06 Dec 2013 09:29:00 GMT Study questions role of vitamin D in disease|
"Doubt cast on vitamin D's role against disease," reports BBC News. The news come from a study summarising a large body of evidence from the best kind of trials – randomised controlled trials (RCTs).
The results of these trials showed that vitamin D supplements didn't appear to help prevent many diseases, including cancer and cardiovascular disease. Importantly, these trials did not cover – so do not apply to – diseases affecting the bones.
The review also highlighted that observational research has consistently found a link between low vitamin D levels and an increased risk of disease, including cardiovascular diseases, inflammatory and infectious diseases.
Because the RCTs did not show that vitamin D supplements helped these diseases, the researchers concluded that vitamin D deficiency might be a symptom related to these conditions, rather than the cause.
However, the reasons why the trials may have found no link between vitamin D supplementation and disease prevention include:
It is not clear which explanation is the correct one at this stage, but the study authors highlight that research scheduled to report in 2017 may clarify whether vitamin D supplements protect against non-bone diseases.
Where did the story come from?
The study was carried out by researchers from French and Belgian research institutions and was funded by the International Prevention Research Institute.
It was published in the peer-reviewed medical journal, The Lancet Diabetes and Endocrinology.
The media reporting was generally balanced and included both the study's conclusions and comments on some of its limitations.
What kind of research was this?
This was a systematic review of evidence from prospective and intervention studies (randomised controlled trials) looking at whether low vitamin D levels caused various diseases, or whether disease caused low vitamin D levels. The effect of vitamin D supplementation on preventing disease was also looked into.
The researchers say low vitamin D levels have been associated with many diseases. However, the researchers pointed out that it is not clear whether low vitamin D is the cause of disease, or whether ill health causes vitamin D levels in the body to fall.
Vitamin D is vital for good bone health, so supplementation may be expected to have an effect on conditions that affect the bones and bone density. However, this research looked at a variety of diseases that do not affect bones – so-called non-skeletal diseases.
What did the research involve?
The research involved searching electronic databases to identify all published scientific research investigating vitamin D and disease up to 2012. The researchers focused on two specific style types: prospective studies and randomised control trials.
Prospective studies can't prove cause and effect, but well-designed randomised control trials can, so the two study design types were included to ensure all the best available evidence was considered and to see if the findings were similar.
All the studies included measures of blood vitamin D levels before the development of any disease. Where possible, the main analysis synthesised all the published results into a single summary measure.
What were the basic results?
The systematic review included 290 prospective cohort studies (279 on disease occurrence and 11 on cancer characteristics or survival) and 172 randomised trials on major health outcomes and physiological parameters related to disease risk, death or inflammatory status.
Results from observational prospective studies
Investigators of most prospective studies reported moderate to strong links between low vitamin D concentrations in the blood and higher risks of illness or disease, including:
High vitamin D concentrations were not associated with a lower risk of cancer, except colorectal (bowel) cancer. This indicated there was a link between low vitamin D levels and a host of different diseases, but cause and effect was not clear, so the pooled results from the RCTs aimed to find out what was causing what.
Results from RCTs
Results from intervention studies did not show a link between vitamin D supplementation and disease occurrence across the range of diseases tested, including colorectal cancer.
The 34 intervention studies included 2,805 individuals with an average (mean) vitamin D concentration lower than 50nmol/l at baseline. The trials found that supplementation with 50 micrograms per day or more of vitamin D did not have a significant effect on the risk of developing the various diseases examined. Supplementation in elderly people (mainly women) with 20 micrograms of vitamin D per day was reported to slightly reduce all-cause mortality.
How did the researchers interpret the results?
The researchers concluded that, "The discrepancy between observational and intervention studies suggests that low 25(OH)D [vitamin D] is a marker of ill health.
"Inflammatory processes involved in disease occurrence and clinical course would reduce 25(OH)D [vitamin D], which would explain why low vitamin D status is reported in a wide range of disorders.
"In elderly people, restoration of vitamin D deficits due to ageing and lifestyle changes induced by ill health could explain why low-dose supplementation leads to slight gains in survival."
This large systematic review suggests that low vitamin D levels in the blood may be the result of disease and illness, rather than the cause of it.
The review also found that vitamin D supplementation did not appear to help reduce the risk of developing non-skeletal diseases (diseases not affecting the bones) in people with low vitamin D levels in a range of diseases. Consequently, this review has cast doubt on the usefulness of people taking vitamin D to reduce their risk of any other diseases not affecting the bones.
This research is useful in drawing attention to the evidence gaps around the role of vitamin D in non-skeletal diseases. However, one of the main points to note is that the research did not cover bone diseases.
Vitamin D is essential for good bone health, particularly during times of skeletal growth (such as during infancy and childhood). The main reason that vitamin D supplementation is recommended is to increase bone health in people who may not be getting adequate vitamin D through natural sources.
The effect of vitamin D on bone health was not addressed, so readers shouldn't conclude that this research casts doubt on the usefulness of taking vitamin D supplements for good bone health – this study only relates to the effects on diseases not affecting the bones.
However, this review still doesn't prove that vitamin D definitely has no effect on non-skeletal diseases. A consistent link was found in observational studies, which was not seen in RCTs. There are a number of possible explanations that could explain this finding in the RCTs:
These issues were discussed by the study authors, who suggested that the vitamin D dose in the RCTs was probably not an issue. However, it is not clear which of these explanations, or alternatives, is correct.
The study highlights that further research needs to look into the effect of vitamin D on diseases not affecting the bones. It also shows that when studies look at non-skeletal diseases, researchers need to pay special attention to specific issues, such as the level of vitamin D deficiency and the dose and duration of supplementation, to eliminate alternative explanations for results like these. The researchers report that such research is underway and may be ready in 2017.
Who should have daily vitamin D supplements?
The Department of Health currently recommends a daily vitamin D supplement for those who may be at risk of deficiency. This includes:
These people should have 10 micrograms for adults, including pregnant women, and 7 to 8.5 micrograms for babies and children.
Links To The Headlines
Lack of vitamin D 'is symptom not cause of illness'. The Times, December 6 2013
Doubt cast on vitamin D's role against disease. BBC News, December 6 2013
Links To Science
Autier P, et al. Vitamin D status and ill health: a systematic review. The Lancet Diabetes & Endocrinology. Published online December 6 2013
|Fri, 06 Dec 2013 09:23:00 GMT Number of teen mothers falls by 8% in a year|
BBC News and the Metro both covered new official statistics on births in England between April 2012 and March 2013.
The detailed data, on all births in NHS hospitals in England during the last year, showed deliveries for teenage mothers (ages 13 to 19) had fallen 8.4% on the previous year and revealed huge differences in birth rates linked to deprivation.
Interviewees in the media welcomed the overall reduction, highlighting it may be a sign of success for sustained sexual health and education efforts aimed at reducing the nation’s high levels of teenage births. However, some also warned against complacency, noting that the UK still has higher teenage pregnancy rates than much of western Europe.
As well as the number of births to teenage mothers, the new statistics paint a detailed picture of the nation’s latest birthing behaviour, including the proportion of “spontaneous” deliveries (not medically induced or requiring a caesarean section), those requiring no anaesthetic before or during delivery, and length of hospital stay.
What is the basis for the teenage pregnancy figures?
The news followed the latest release of official maternity statistics from the Health and Social Care Information Centre. The data collected is vast and detailed, covering all aspects of births in NHS hospitals in England. It includes private patients treated in NHS hospitals, patients who were resident outside of England, and care delivered by treatment centres (including those in the independent sector) funded by the NHS. It does not cover births occurring outside of NHS hospitals such as home births or those in private hospitals.
Maternity data is presented as “delivery episodes”. This is in effect, the number of mothers not the number of births. Multiple births (twins, triplets, and so on) are only counted once. In the rare event mothers have more than one delivery in a year, they are counted more than once.
Was deprivation linked to any differences in teenage pregnancy rates?
Both media headlines chose to lead with the teenage deliveries figures. Both also reported startling differences between the birth rates of women from the least deprived areas of England and those living in the most deprived areas.
The figures showed birth rates were approximately twice as high for women living in the most deprived areas compared with least deprived. The birth rate was 37.2 per 1,000 women in the most deprived areas compared with 18.6 per 1,000 in the least deprived areas. The difference was even larger for teenage mothers: 31.1 per 1,000 teenage girls in the most deprived areas compared with 3.6 per 1,000 teenage girls in the least deprived.
Importantly, the measure of deprivation used, called IMD scores, comprise seven different areas – some of which may directly correlate with age. So for example, the younger the person, the more likely that they are in employment which pays lower wages. It wasn’t clear to what extent the large differences observed were due to this age correlation, or due to the non-age linked domains.
Birth rates also varied by location. The north east saw the highest rate of teenage births, the lowest was in London.
How much have deliveries for teenage mothers fallen?
The data showed that hospital deliveries for teenage mothers have been falling since 2007 – the earliest year reported in the statistical release. There were 42,671 hospital deliveries to teenage mothers in England in 2007/8, which had reduced steadily to 30,794 by 2012/13, the latest figures.
Over the last year (2011/12 to 2012/13) there were 2,827 fewer deliveries, which was a reduction of 8.4%, the figure picked up and used in the media's headlines.
How do English teenage pregnancy rates compare with other countries?
The statistics released today were only for England so they don’t address this question directly. However, the BBC interviewed Natika Halil of the FPA (Family Planning Association), who said: "While the figures are promising, we are still not at the levels recorded in comparable western European countries, so we must keep up the momentum."
What else do the English maternity statistics show?
The key facts from the report included:
Links To The Headlines
Teenage birth rate down 8% in a year. BBC News, December 5 2013
Number of teenage mothers drops eight per cent. Metro. December 5 2013
|Thu, 05 Dec 2013 11:00:00 GMT UK cancer survival rates below European average|
“Cancer survival in Britain the worst in Europe,” The Daily Telegraph reports.
This and many other similar headlines are prompted by a major new study on cancer survival rates in Europe from 1997 to 2007.
While survival rates have tended to improve, cancer survival still varies widely between European countries. The lowest survival rates for most cancers were found in eastern Europe.
The study also found that the UK and Ireland has lower survival rates than the European average for many cancers, particularly of the colon, ovary, kidney, stomach and lung. The lung cancer survival rate in particular was far lower than for other regions. The UK has about average survival rates for cancer of the rectum, breast, prostate, melanoma of the skin and lymphomas.
Researchers say the main reason for low survival rates in the UK seems to be delayed diagnosis, underuse of successful treatments and unequal access to treatment, particularly among elderly people.
However, patient factors are not accounted for, such as the level of smoking, alcohol misuse and poor diet in the UK.
It could be the case that poor cancer care in the UK is not solely to blame for the below average cancer survival rates, but may also be related to the factors listed above.
Where did the story come from?
The study was carried out by researchers from a number of centres across Europe including the London School of Hygiene and Tropical Medicine in the UK. It was funded by the European Commission, Italian Ministry of Health and the Cariplo Foundation.
The study was published in the peer-reviewed medical journal Lancet Oncology.
Unsurprisingly, the research got wide coverage in the UK press, with the Mail Online pointing out that cancer survival rates in the UK were often on a par with former states of the eastern bloc and below comparable countries such as France and Germany. The Mail also included comments from NHS England as well as cancer charities, while The Guardian linked the study to a story about reported moves to raise awareness of cancer among older people.
The good news about the improvements in childhood cancer rates appears to have been ignored.
Links To The Headlines
Cancer survival in Britain the worst in Europe. The Daily Telegraph, December 5 2013
UK cancer survival rates ‘lag behind Europe’ for nine of the ten most common forms. The Independent, December 5 2013
Cancer Survival Rates Are 'Truly Depressing'. Sky News, December 5 2013
UK has worst ovarian cancer survival rate for women in Europe as delays blamed for poor results. Daily Mirror, December 5 2013
UK cancer survival rates 'low'. ITV News, December 5 2013
Cancer care shame as UK survival rate is one of EU’s worst. Daily Express, December 5 2013
UK's survival rates worse than European average for 9 out of 10 major cancers. Daily Mail, December 5 2013
Links To Science
De Angelis R, Sant M, Coleman MP, et al. Cancer survival in Europe 1999-2007 by country and age: results of EUROCARE-5 – a population-based study. The Lancet. Published online December 5 2013