Press releases Monday 9 August to Saturday 14 August 2010

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(1) Colder days raise the risk of more heart attacks
(2) UK breast cancer mortality rates have fallen faster than in other European countries
(3) Access to hip and knee replacement across England is unfairly skewed
(4) Patients prefer tablets to chocolate to treat high blood pressure

(1) Colder days raise the risk of more heart attacks
(Research: Short term effects of temperature on risk of myocardial infarction in England and Wales: time series regression analysis of the Myocardial Ischaemia National Audit Project (MINAP) registry)
(Editorial: Temperature changes and the risk of cardiac events)

A drop in the average temperature outside is linked to a higher risk of people having heart attacks, according to a new study published on bmj.com today.

UK researchers found that each 1°C reduction in temperature on a single day is associated with around 200 extra heart attacks.

In the light of global climate change, the relations between weather and health are of increasing interest. Previous studies have shown that ambient outdoor temperature is linked to mortality risk in the short term, with both hot and cold days having an effect, but the effect of temperature on the risk of myocardial infarctions (heart attacks) is unclear.

Researchers from the London School of Hygiene and Tropical Medicine carried out a study to examine the short term relation between ambient temperature and risk of heart attack.

They analysed data on 84,010 hospital admissions for heart attack recorded in the Myocardial Ischaemia National Audit Project (MINAP) during 2003-2006, and daily temperatures from the British Atmospheric Data Centre, focusing on 15 geographical areas in England and Wales.

The results were adjusted to take into account factors such as air pollution, influenza activity, seasonality and long term trends.

The researchers found that a 1°C reduction in average daily temperature was associated with a cumulative 2% increase in risk of heart attack for 28 days. The highest risk was within two weeks of exposure.

The heightened risk may seem small, but the UK has an estimated 146,000 heart attacks a year and 11,600 events in a 29 day period, so even a small increase in risk translates to substantial numbers of extra heart attacks, around 200 for each 1°C reduction in temperature nationwide on a single day.

Older people between the ages of 75 and 84 and those with previous coronary heart disease seemed to be more vulnerable to the effects of temperature reductions, while people who had been taking aspirin long-term were less vulnerable.

The researchers found no increase in the risk of heart attacks at higher temperatures, possibly because temperature in the UK is rarely very high in global terms.

In conclusion, they say “our study shows a convincing short term increase in risk of myocardial infarction associated with lower ambient temperature, predominantly operating in the two weeks after exposure.”

They call for further studies to help shed light on the role of adaptive measures such as clothing and home heating, and further clarify which groups are likely to be the most vulnerable.

In an accompanying editorial, Dr Paola Michelozzi and Manuela De Sario, of the Lazio Region Department of Epidemiology in Rome, write: Heat and cold exposure affect people with cardiovascular diseases and increase the incidence of coronary events with high impact on short term mortality. Moreover, while the effect of cold on myocardial infarction is well documented, the short-term effect of heat is still contradictory but cannot be disregarded.

This is even more relevant under climate change scenarios that predict a decrease of cold related mortality that will be outweighed by an increase in cardiovascular mortality and morbidity associated with increased frequency and intensity of heat waves.

Clinicians should be aware that exposure to environmental heat and cold is a risk factor for cardiovascular disease and should consider this in risk prevention and management, and efforts should be especially directed towards most vulnerable individuals identified by a multiplicity of risk factors.

Contacts:
Research: Krishnan Bhaskaran, Research Degree Student, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
Email: krishnan.bhaskaran@lshtm.ac.uk

Editorial: Manuela De Sario, Epidemiologist, Lazio Region Department of Epidemiology, Rome, Italy
Email: desario@asplazio.it

(2) UK breast cancer mortality rates have fallen faster than in other European countries
(Research: Disparities in breast cancer mortality trends between 30 European countries: retrospective trend analysis of WHO mortality database)
(Editorial: UK cancer survival statistics)

Population-based breast cancer mortality rates in the UK have fallen steeply in the last two decades - more than in any other major European country, finds a study published on bmj.com today. These results challenge claims that survival after breast cancer is worse in the UK than elsewhere in western Europe.

The apparently poor UK survival rates are misleading because of shortcomings in the way cancers are registered in the UK, whereas the population-based mortality rates are reasonably reliable, says an accompanying editorial.

Since the late 1980s, breast cancer mortality rates have been falling in many European countries. This has been largely attributed to the combined effects of early diagnosis, including breast screening, and the effective treatment of breast cancer.

A team of researchers led by Philippe Autier from the International Prevention Research Institute in France, examined changes in breast cancer mortality rates in women living in 30 European countries from 1980 to 2006.

Using World Health Organisation data, mortality rates were calculated for all women and by age group (less than 50 years, 50-69 years and 70 years and over).

From 1989 to 2006, breast cancer mortality decreased by 20% or more in 15 European countries. In the UK, mortality rates fell by about 30%, more than in any other major European country. In France, Finland and Sweden, that have also invested much in breast screening and new cancer drugs, mortality rates decreased by 10-16%.

In central European countries, breast cancer mortality rates did not decline and even increased during the last two decades.

Women aged under 50 showed the biggest reductions in mortality rates, although screening at that age is uncommon. This may reflect better targeting of effective treatments, suggest the authors. They also suggest that the sustained decline observed in many countries seems to indicate that breast cancer mortality will continue to decrease beyond 2006.

The authors call for better data collection to help understand the variations in breast cancer mortality across Europe and action to reduce avoidable breast cancer mortality in central European countries.

In an accompanying editorial, Valerie Beral and Richard Peto, at the University of Oxford, point out that cancer registration in the UK is known to be incomplete and that defects in these data make cancer survival rates appear significantly worse than they really are. By contrast, the registration of death is complete, deaths from breast cancer are well recorded (except at old age), and so population-based mortality trends in middle age are fairly reliable.

They conclude that the rapid decline in UK population-based breast cancer mortality rates in middle age (see graph - link below) are valid and that failure to make proper allowances for the shortcomings of cancer registration data “may well have led to misleading claims about the supposed inferiority of UK cancer treatment services in general."

Contacts:
Research: Philippe Autier, Research Director, International Prevention Research Institute, Lyon, France
Email: philippe.autier@i-pri.org

Editorial: Valerie Beral, Professor of Epidemiology; University of Oxford, UK
Email: pa.valerie.beral@ceu.ox.ac.uk

(3) Access to hip and knee replacement across England is unfairly skewed
(Research: Equity in access to total joint replacement of the hip and knee in England: cross sectional study)
(Editorial: Unequal access to health care in England)

Peoples’ access across England to total joint replacement of the hip or knee is uneven and affected unfairly by age, sex, deprivation, geography and ethnicity, according to a new study published on bmj.com today.

The results show that women, elderly people, and those in deprived areas continue to be worse off.

Total joint replacement of the hip or knee is a common procedure, which is cost effective and boosts public health. There were 82,419 knee operations in 2008-09 in England and 77,608 hip operations.

Fairness in access to healthcare is a founding principle of the health service and local primary care trusts (PCTs) are required to conduct Health Equity Audits.

Researchers from the UK and Canada set out to explore the geographical and socio-demographic factors linked to variation in equity of access to these operations.

They used data from the Somerset and Avon Survey of Health (a small-area population based survey), the English Hospital Episode Statistics (HES) database and the English Longitudinal Study of Aging (ELSA) – a nationally representative population based survey of 11,329 people aged 50 and over living in private households in England.

The Somerset survey and ELSA data gathered between March 2002 and March 2003, allowed the researchers to work out predicted rates of need of total knee or hip replacement amongst the population.

They then used the HES data to calculate actual provision of these operations for patients aged 50 or over during 2002.

They combined the different sources of routine data into a single model and found there was clear evidence of under-provision of hip and knee replacement relative to need.

Results showed that people aged 60-84 were more than twice as likely to have received an operation than people aged 50-59, despite all people in both groups having an equal need. People aged 85 and over, however, were less likely to have had the operations.

Men received 31% more knee replacements relative to need than women and 8% more for hip replacements.

People living in deprived areas were found to receive around 70% less provision relative to need compared with the most affluent areas for both knee and hip replacements.

Those living in urban areas got greater provision of knee replacement relative to need than people living in more isolated places, but the effect was different for hip replacement with people in villages or isolated areas getting the most provision relative to need.

These results are illustrated in two maps in the full paper (see link below).

The ethnic mix of an area made no difference for hip replacements, but people living in non-white areas were more likely to receive a knee replacement than people residing in mostly white areas.

The authors conclude: “Policy makers should examine factors at the patient or primary care level to understand the determinants of inequitable provision.”

Although this study provides a major methodological advance, the implications of its findings for current policy are limited because the data are from 2002, say Professors Ann Bowling and Martin McKee, in an accompanying editorial.

Investment in the NHS has increased since then. Hence the considerable under-provision recorded here is likely to have been alleviated to some extent, they write, although they cannot be sure of this.

They believe that further analyses using both NHS and private sector data are needed to know whether the health needs of the population are being met and ask why any inequalities exist and how they can be tackled.

Now that the Department of Health in England has signified its intent to move to general practice commissioning, they ask who, if anyone, will have the skills or interest to take on this important role?

Contacts:
Research: Andrew Judge, Senior Statistician, NIHR Musculoskeletal Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, UK
Email: andrew.judge@ndorms.ox.ac.uk

Editorial: Ann Bowling, Professor of Health Services Research, Department of Primary Care and Population Health, University College London, UK
Email: a.bowling@ucl.ac.uk

(4) Patients prefer tablets to chocolate to treat high blood pressure
(Letter: Chocolate dose may be too much)

Given the choice, patients would rather pop a pill than have a daily bar of chocolate to lower their blood pressure, according to a letter published in this week’s BMJ.

A recent study by Karin Ried and colleagues at the University of Adelaide suggested that dark chocolate may be better than placebo in reducing high blood pressure. However, in another study they found that taking 50 g of 70% cocoa chocolate daily was significantly less acceptable than one capsule daily of placebo or tomato extract, making the practicability of chocolate as a long term treatment debatable, they say.

Contact:
Karin Ried, Research Fellow, Discipline of General Practice, University of Adelaide, Adelaide, Australia
Email: karin.ried@adelaide.edu.au

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