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Press releases Saturday 2 November 2007

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(1) New studies add weight to link between pre-eclampsia and heart disease
(2) Patients denied admission to intensive care because of doctors' pessimism
(3) Litvinenko poisoning caused limited public concern
(4) New report shows how our diet must change to cut cancer risk

(1) New studies add weight to link between pre-eclampsia and heart disease
(Pre-eclampsia and the risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis)
http://www.bmj.com/cgi/content/full/bmj.39335.385301.BEv1
(Pre-pregnancy cardiovascular risk factors as predictors of pre-eclampsia: population based cohort study)
http://www.bmj.com/cgi/content/full/bmj.39335.385301.BEv1
(Editorial: Pre-eclampsia and increased cardiovascular risk)
http://www.bmj.com/cgi/content/full/bmj.39337.427500.80v1

Two studies, published together on bmj.com today, add further weight to the theory that pre-eclampsia and cardiovascular diseases may share common causes or mechanisms.

The first study finds that women who have had pre-eclampsia during pregnancy have a more than two fold higher risk of heart disease in later life, while the second shows that women with cardiovascular risk factors that are present years before pregnancy may be predisposed to pre-eclampsia.

Pre-eclampsia is a serious condition where abnormally high blood pressure and other disturbances develop in the second half of pregnancy. It affects about 5% of all first-time pregnancies and is dangerous for both mother and child.

In the first study, researchers in London analysed 25 studies involving over 3 million women to calculate the future health risks of women who have had a pregnancy affected by pre-eclampsia that is likely explained by the association with heart disease.

They found a small increase in overall mortality among women who had had pre-eclampsia. Women with a history of pre-eclampsia also had an almost four fold increased risk of high blood pressure (hypertension) and a two fold increased risk of fatal and non-fatal ischaemic heart disease, stroke, and blood clots (venous thromboembolism) in later life.

They found no increase in risk of any cancer, including breast cancer, suggesting a specific relationship between pre-eclampsia and cardiovascular disease.

The authors explain that, since the risk of a cardiovascular event increases with age, and assuming that the effect of the pre-eclampsia is independent of other risk factors, absolute risk at age 50-59 years would be around 8% without and 17% with a history of pre-eclampsia and at 60-69 years the risk would be 14% without and around 30% for a woman with a history of pre-eclampsia.

This suggests that a woman with pre-eclampsia might become eligible for preventative therapies at an earlier age than would otherwise be the case.

The mechanism underlying this association remains to be defined, but whatever its nature, a history of pre-eclampsia should be considered when evaluating risk of cardiovascular disease in middle aged women, they conclude.

In the second study, researchers in Norway examined whether cardiovascular risk factors assessed before conception predict pre-eclampsia.

3,494 women were included in the analysis. Several cardiovascular risk markers, including blood pressure, cholesterol and blood sugar levels, weight, and body mass index, were recorded before pregnancy.

133 (3.8%) of these women had a pregnancy complicated by pre-eclampsia. After adjusting for factors such as smoking and social status, the odds of pre-eclampsia were seven times greater in women with high pre-pregnant blood pressure, total cholesterol and blood sugar levels compared to women with readings in the normal range.

Furthermore, a family history of high blood pressure, ischaemic heart disease, or diabetes was each associated with a doubling in risk, while overweight and obese women also had a higher risk compared to women of normal weight. Women who used oral contraceptives before pregnancy had half the risk of pre-eclampsia compared to never or previous users.

These results show that unfavourable cardiovascular risk factors that were present years before pregnancy are strong predictors of pre-eclampsia, suggesting that pre-eclampsia and cardiovascular diseases may share a common origin, say the authors.

However, this does not rule out the possibility that the pre-eclamptic process itself may also contribute to subsequent cardiovascular risk, they conclude.

An accompanying editorial says that guidelines for prevention of cardiovascular disease are appropriate for all women, while future research must investigate whether women with previous pre-eclampsia should have their cardiovascular risk markers treated earlier and more aggressively (or both).

Contacts:
Paper 1: David Williams, Consultant Obstetric Physician, Institute for Women's Health, Elizabeth Garrett Anderson Obstetric Hospital, University College London, UK
Email: d.williams@uclh.nhs.uk 

Paper 2: Elisabeth Balstad Magnussen, Research Fellow, Department of Public Health, Faculty of Medicine, Trondheim, Norway
Email: elisabeth.b.magnussen@ntnu.no 

Pål Richard Romundstad, Associate professor, Department of Public Health, Faculty of Medicine, Trondheim, Norway
Email: pal.romundstad@ntnu.no 

(2) Patients denied admission to intensive care because of doctors' pessimism
(Implications of prognostic pessimism in patients with chronic obstructive pulmonary disease (COPD) or asthma admitted to intensive care in the UK within the COPD and asthma outcome study (CAOS): multicentre observational cohort study)
www.bmj.com/cgi/content/full/bmj.39371.524271.55v1
(Deciding who to admit to a critical care unit)
www.bmj.com/cgi/content/full/bmj.39378.654329.80v1

Doctors are overly pessimistic about the chances of survival for patients with COPD related attacks and, as a result, some patients may be denied admission to hospital for vital help, according to a study published today on bmj.com.

COPD (chronic obstructive pulmonary disease) causes around 30,000 deaths a year in the UK and many patients who have COPD attacks can benefit from assisted ventilation, but they have to be admitted to an intensive care unit (ICU) to be intubated.

Researchers studied results from 92 intensive care and three respiratory high dependency units in the UK that dealt with 832 patients aged 45 years and over who had breathlessness, respiratory failure or change in mental status due to a COPD attack, asthma or both.

Information gathered over an 18-month period from a database covering 74% of UK ICUs said there was no significant difference in outcomes when comparing units that took part in the study and those that did not.

Overall, 517 (62%) patients survived to 180 days after the incident, but clinicians prognoses were pessimistic, predicting a survival rate of just 49%.

For the fifth of patients with the poorest prognosis according to the clinician, the predicted survival rate was 10% and the actual rate was 40%

The survival rates were 80% at discharge from ICU or high dependency units, 70% at discharge from hospital and 62% at 180 days after ICU admission.

The authors say: "Clinicians are generally pessimistic about the survival of patients with exacerbations of COPD and have particular problems in identifying those with poor prognosis. Patients might therefore be inappropriately excluded from intensive care and the chance of intubation on the basis of a false prediction of futility."

In an accompanying editorial, US researchers point to a scarcity of intensive care resources as a possible explanation for these results.

They say that making decisions about admission to intensive care is complex, especially in the UK and southern Europe, where intensive care beds are often lacking. And they call for further studies to determine whether prognostic pessimism requires intervention aimed at doctors or at underlying healthcare systems that have inadequate provision of critical care services.

Contacts:
Research: Martin Wildman, Consultant in Respiratory Medicine, Northern General Hospital, Sheffield, UK
Email: martin.wildman@sth.nhs.uk 
Editorial: Dale Needham, Assistant Professor, Johns Hopkins Medical Institutions, Division of Pulmonary and Critical Care Medicine, Baltimore, USA
Email: cbrownlee@jhmi.edu 

(3) Litvinenko poisoning caused limited public concern
(Public information needs after the poisoning of Alexander Litvinenko with polonium-210 in London: cross sectional telephone survey and qualitative analysis )
www.bmj.com/cgi/content/full/bmj.39367.455243.BEv1
(Editorial: Communicating risk to the public after radiological incidents)
www.bmj.com/cgi/content/full/bmj.39377.655845.80v1

The fatal poisoning of Alexander Litvinenko with radioactive polonium-210 in London in 2006 caused limited public concern about potential health risks, according to a study published on bmj.com today.

During major public health incidents, health agencies and emergency services often need to reassure the public about the level of risk involved, advise them of measures that are being taken to safeguard public health, and specify what actions individuals can take to minimise their own risk. Learning lessons from any relevant events that occur in the real world is therefore vital.

So researchers at King's College London and the Health Protection Agency (HPA) assessed public perceptions of the risk to health and the impact of public health communications following the death of Alexander Litvinenko from radioactive polonium-210 in central London on 23 November 2006.

They carried out a telephone survey of a representative sample of adult Londoners during the incident. Interviews were also conducted with a sample of the public who had been in a contaminated area (a central London sushi restaurant and the bar of a London hotel).

One thousand people completed the telephone survey and 86 took part in the interviews.

One hundred and seventeen (11.7%) of those surveyed perceived their health to be at risk. Factors associated with perceiving one's health to be at risk included being female, having a non white ethnic background, having a household income of under £30,000 per year, and renting one's home.

Levels of knowledge about polonium-210 were generally low, with recognition of HPA messages ranging from 15% to 58%. The exception was the statement that "If you have not been in one of the areas known to be contaminated with polonium-210, then there is no risk to your health." 71% of participants recognised that this was correct.

Participants who believed that the incident was related to terrorism or a public health threat were more likely to believe that their health was at risk than those who reported that it was related to espionage or was aimed at a single person.

Most (80%) also felt the HPA's response to the incident had been "appropriate or about right."

Interviewees were also generally satisfied with the information they received, though would have preferred more information about their individual risk of exposure, the results of their urine tests, and the health implications of the incident.

Despite involving radioactive contamination in the heart of a major city, these results show that the polonium incident caused limited public concern about potential health risks, say the authors.

This was partly due to the perception of the incident as a 'spy story' and partly due to successful communication about the restricted nature of any risk. Had the incident been portrayed as linked to terrorism, public concern might have been greater.

Care should be taken in future incidents to ensure that detailed, comprehensible and relevant information about the risks of exposure is made available to those who require it, they conclude.

This view is supported in an accompanying editorial that calls for improved crisis and emergency risk communication to be at the heart of future planning and training.

The research also continues to show that the general public is more resilient in the face of new threats than is sometimes anticipated.

Contact:
G James Rubin, Lecturer, King's College London, Institute of Psychiatry, Department of Psychological Medicine, London, UK
Email: g.rubin@iop.kcl.ac.uk 

(4) New report shows how our diet must change to cut cancer risk
(Editorial: Diet and the risk of cancer)
http://www.bmj.com/cgi/content/full/335/7625/897

A new report published this week by the World Cancer Research Fund (WCRF) will show how much our diet needs to change if we are to reduce the risk of cancer.

In this week's BMJ, Professor Tim Key from the Cancer Research UK unit at the University of Oxford discusses what would be needed to achieve the report's goals.

The report concludes that obesity increases the risk of cancer of the oesophagus, colorectum, pancreas, breast, endometrium, and kidney. Its goal is for the average body mass index of the population to be between 21 and 23.

Yet, mean body mass index in adults in the UK is now about 27 and has not fallen into the target range since the 1940s, says Professor Key. Enormous efforts by individuals, society, and government will therefore be needed to reverse the current trend.

The report also shows that alcohol increases the risk of cancers of the mouth, pharynx, larynx, oesophagus, colorectum, and breast and also causes cirrhosis, which predisposes to liver cancer. It recommends much lower drinking limits than currently advised in Britain, so a substantial shift in drinking habits would be needed to achieve these goals.

Evidence for a protective effect of fruit and vegetables is less convincing. Nevertheless, the report recommends that people should eat at least five portions of vegetables and fruits each day.

To meet this individual recommendation, the average consumption in the population would need to be about 7.5 portions a day. The average consumption in Britain is currently about three portions a day, says Professor Key, so the consumption of fruit and vegetables would need to be more than doubled.

The major new conclusion in the report is that red and processed meat convincingly cause colorectal cancer. This is based on results from several studies showing that, on average, people who ate the most red or processed meat had about a 30% increased risk compared with those who ate the least. The report therefore recommends that the average intake of red and processed meat in the population should be no more than 300g each week.

In most regions of the world, total meat consumption is well above this goal. In Britain, the current mean intake is about 970g a week in men and about 550g a week in women, so reaching this goal would require a large reduction in meat consumption.

The report identified several foods and nutrients for which some evidence exists of a beneficial effect on the risk of cancer. For example, foods rich in folate may reduce the risk for cancer of the pancreas, and diets rich in calcium may reduce the risk for colorectal cancer.

Professor Key believes that, while the effects of obesity and excessive alcohol consumption are clear, the goal for intake of fruit and vegetables has financial and environmental implications and requires careful consideration.

It may be better to concentrate efforts on increasing the consumption of plant foods such as cereals and beans, which supply energy and protein and can therefore partially replace meat, he concludes.

These wider questions will be dealt with in the WCRF's policy report, due to be published next year.

Contact:
Professor Tim Key, Cancer Research UK, Oxford University, Oxford, UK
Email: Paul.Thorne@cancer.org.uk 

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