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A diet combining fruit and vegetables with foods such as fish, poultry and nuts “can protect you against heart attack”, reported The Independent.

The news is based on a well-conducted trial which tested the DASH diet, a diet high in fruit and vegetables but low in saturated fat that is recommended by the US government. The study enrolled 459 healthy people with slightly high blood pressure and randomly assigned them to follow the DASH diet, a high-fat “American” diet or an American diet supplemented with more fruit and vegetables. After eight weeks, the DASH diet lowered blood pressure and cholesterol, and decreased the participants’ risk of developing heart disease in the next 10 years more than the other diets.

This study has numerous strengths, but it only estimated future heart disease risk rather than monitoring participants over 10 years. Additionally, the risk of heart disease at the start of this study was also very low at only 1%, and the DASH diet reduced this risk by only a minimal amount. Despite these small limitations, this study demonstrates the importance of blood pressure as a risk factor for coronary heart disease and the role a balanced diet might play in reducing this risk.

 

Where did the story come from?

This study was carried out by researchers from Johns Hopkins University, Baltimore. This particular trial was funded by the US National Center for Research Resources, and individual researchers received various other grants and research awards. The trial used data from a previous study, the DASH trial, which was sponsored by the US National Heart, Lung and Blood Institute. The study was published in the peer-reviewed medical journal Circulation.

In general, The Independent accurately reflected the findings of this well-conducted study, but did not mention some important limitations.

 

What kind of research was this?

This randomised controlled trial investigated the effects of dietary pattern on the 10-year risk of coronary heart disease (CHD). A randomised controlled trail is the best way of investigating a treatment’s ‘efficacy’, i.e. its effectiveness under ideal test conditions.

Dietary studies frequently have an inherent limitation in that it is difficult to accurately control how well a person adheres to the experimental diet being tested. However, this trial had the benefit of providing all the participants’ meals.

 

What did the research involve?

The researchers analysed findings of the Dietary Approaches to Stop Hypertension (DASH) trial, a previous study that assessed how various short-term dietary interventions affected high blood pressure. The trial had enrolled 459 healthy people with an average age of 45 and blood pressure that was on the high side of normal (average 131/85 mmHg) but not yet considered to be high. The researchers excluded participants with any significant illness, high cholesterol, any cardiovascular event in the previous six months or a BMI higher than 35kg/m2 (a BMI over 25kg/m2 is above ideal weight).

Participants were randomly assigned to follow one of three dietary patterns for eight weeks:

• a control diet: a “typical American diet”, high in saturated fat and cholesterol, low in minerals such as calcium and magnesium
• the F/V diet: rich in fruit and vegetables but otherwise similar to the control diet
• the DASH diet: rich in fruit, vegetables and low-fat dairy, and with a higher ratio of polyunsaturated fat to saturated fat than the other diets

Diets were reportedly prepared in research kitchens, with lunch and dinner prepared on site and breakfast provided for participants in a cooler to be eaten at home. Participants were also asked to record any additional items they consumed, including drinks and added salt. Blood pressure was measured on five occasions during the last two weeks of the study and the average measure was calculated. Cholesterol was also checked.

This subsequent study took the data from the DASH trial and applied the Framingham heart risk tool, a recognised method for predicting an individual’s risk of developing coronary heart disease (CHD). The researchers estimated the 10-year CHD risk of each participant at the beginning of the study and after eight weeks of their assigned diet. This heart risk calculation method takes into account several factors that can contribute to CHD risk, including gender, age, blood pressure, smoking status and diabetes.

 

What were the basic results?

At the start of the study, all participants had a low risk of developing CHD within the next 10 years (0.98% on average). The researchers found that, compared with the control diet, following the DASH diet for eight weeks:

• lowered blood pressure
• lowered total cholesterol
• lowered LDL (“bad” cholesterol)
• lowered HDL (“good” cholesterol)

At the end of the eight-week study period, there was no significant difference in 10-year CHD risk between the control and F/V diet groups. However, the DASH group had a significantly greater decrease in their 10-year CHD risk compared to the control group and to the F/V group.

Over the course of the trial, participants in the DASH group had:

• an 18% decrease in their CHD risk compared to those in the control group (relative risk [RR] 0.82, 95% confidence interval [CI] 0.75 to 0.90)
• an 11% decreased risk compared to those in the F/V group (RR 0.89, 95% CI 0.81 to 0.97)

 

How did the researchers interpret the results?

The researchers concluded that the DASH diet, which was low in saturated fat and high in fruit and vegetables, decreased the 10-year CHD risk more than a diet high in fruit and vegetables alone or a typically American control diet that was high in saturated fat.

 

Conclusion

This well-conducted trial benefits from its relatively large size, accurate provision of the three randomised diets and high study completion rates (95%). It also featured a reliable study outcome by using the average of a series of blood pressure measures, which is preferable to relying on a single blood pressure reading.

The study found that eight weeks of the DASH diet, which was rich in fruit and vegetables and low in saturated fat, lowered blood pressure and cholesterol. This contributed to a decrease in predicted 10-year CHD risk. The DASH diet reduced this risk by 18% compared to a high-saturated fat “American” diet and by 11% compared to a diet similar to the American diet but with higher intake of fruit and vegetables.

Some points to note when interpreting this study include:

• All participants in this study had a low risk of developing coronary heart disease in the next 10 years (only about 1%). The DASH diet lowered this 1% risk by approximately one-tenth compared with the diet high in fruit and vegetables and by approximately one-fifth compared to the high-fat diet. Therefore, although the DASH diet lowered risk further, the overall risk remained low in all groups and the differences in risk between the groups were small.
• Although the tool used to calculate 10-year CHD is fairly reliable and commonly used, it is still only an estimate. The people were not followed up over 10 years to see whether they developed heart disease.
• This was only a brief eight-week intervention period. The effects of continuing these diets in the long term are unclear.
• The content of these diets is unclear. Although the newspapers reported that a more balanced diet involving nuts, chicken and fish was the most beneficial, the researchers did not describe the particular foods the participants ate, the calorific content or how much fat and cholesterol the diets contained.
• There were some differences between the three dietary groups at the start of the study. Those in the DASH group had a lower starting cholesterol level than participants in the F/V and control groups. This is an important difference as it could affect blood pressure.
• 60% of the participants in the trial were of African-American ethnicity, 35% were white and the remainder were of other ethnicity. Subgroup analysis also demonstrated that there was a greater decrease in CHD-risk in African-American participants. Therefore, it seems that these results are most applicable to this population group, which should be taken into account when generalising results to all ethnic populations.
• As the researchers acknowledge, this study was too small to reliably predict how the diets tested may affect other population subgroups, such as postmenopausal women, people with higher CHD risk or people with existing CHD.

Overall, this well-conducted study demonstrates the importance of blood pressure as a risk factor for coronary heart disease. It also supports the benefits of fruit and vegetables and low saturated fat as part of a healthy lifestyle to further modify the risk of heart disease.

Links To The Headlines

Revealed: the diet that can protect you against heart attacks. The Independent, August 31 2010

Links To Science

Chen ST, Maruthur NM, Appel LJ. The Effect of Dietary Patterns on Estimated Coronary Heart Disease Risk Results From the Dietary Approaches to Stop Hypertension (DASH) Trial. Circulation: Cardiovascular Quality and Outcomes. Published online before print August 31 2010

“Smoking cannabis from a pipe can significantly reduce chronic pain in patients with damaged nerves,” reported the BBC. It added that improvements in sleep and anxiety were also seen.

This news story is based on a small randomised controlled trial in 23 people, which found that a low dose of inhaled cannabis (lower than that needed to cause euphoria or a “high”) modestly improved reported pain in patients with neuropathic pain.

This is a well-conducted study, but its small size means that it is not possible to tell whether the results demonstrate a real association between cannabis and pain relief, or if they are due to chance.

More research in larger groups of people over a longer period of time is needed to see if the effects of cannabis for this type of pain can be replicated. In addition, there are health concerns related to the use of smoked cannabis, including mental health problems and lung damage.

It is important to point out that cannabis is a class B drug, which is illegal to possess or supply, and is not licensed in any form for medical use.

 

Where did the story come from?

The study was carried out by researchers from McGill University, Canada, and was funded by The Canadian Institutes of Health. The study was published in the (peer-reviewed) Canadian Medical Association Journal.
 
This research was covered well by The Daily Telegraph and the BBC, though the study did not find any evidence for effects on anxiety or depression, as the Telegraph headline suggests.

 

What kind of research was this?

This randomised controlled trial investigated whether cannabis can relieve neuropathic pain (neuralgia) – severe pain caused by the abnormal activity of nerve cells. Various events can set off neuropathic pain, including surgery, trauma or shingles.

The researchers say that although there are drug treatments for neuropathic pain, such as anticonvulsants, antidepressants, opioids and local anaesthetics, their effectiveness varies between patients. Some patients are put off taking them because of unpleasant side effects. They say there is anecdotal evidence that cannabis relieves chronic neuropathic pain and improves sleep. The researchers wanted to investigate whether these reported effects could be replicated under controlled experimental conditions.

This type of study design is the most appropriate way of determining whether a drug is effective. However, this was a very small trial in only 23 people, so it is not possible to conclude that the results are not down to chance alone.

 

What did the research involve?

The study recruited people who had experienced neuropathic pain for at least three months as a result of trauma or surgery. The participants ranked their current level of pain on a 10-point scale, and patients reporting pain intensity greater than four were included. Excluded from the study was anyone whose pain was due to cancer, those who had heart or lung disease, and those who had any type of substance abuse, a history of psychiatric disorders, or who were pregnant. In total 23 people were eligible to participate in the study.

The effect of smoking cannabis with the active ingredient, tetrahydrocannabinol (THC), was compared to smoking cannabis in which the THC had been removed (the control). Different potencies of THC were also compared to each other. Participants were not told the treatment they were given.

The control cannabis that had the THC removed was provided to the researchers by the US National Institute of Drug Abuse. The cannabis doses were prepared by blending the flowers and leaves of the plant to make three different potencies of the active drug (2.5%, 6.0% and 9.4% of THC).

Cannabis doses were delivered as single smoked inhalations taken through a pipe. The participants were instructed to inhale for five seconds as the cannabis was lit, hold the smoke in their lungs for 10 seconds, then exhale. The patients were observed taking the first dose. They then took subsequent doses at home, three times daily for five days. After 14 days, the participants swapped treatments so that those who had received the cannabis without THC then received cannabis containing the active drug. And those who had received active cannabis then received the placebo or a different dose of cannabis treatment.

In total, participants had four cycles of treatment where they received doses of 0%, 2.5%, 6% and 9.4% THC. Throughout the trial, the participants continued any routine medications that they were taking.

On the first day of each treatment period, the participants were asked about their feelings of pain, and how relaxed, stressed or happy they were. Their heart rate was also measured and a blood sample taken. During the five days of treatment or placebo, the participants were contacted by telephone and asked about their pain, how they were sleeping, their medication, and whether they were having any side effects. A urine sample was taken every day. On the fifth day of each treatment, a blood sample was taken and the participants were asked more questions about their pain, mood and quality of life.

 

What were the basic results?

The study had screened 113 participants but only 23 were eligible. Out of these, 21 completed all four cycles.

The researchers found that the average pain intensity was significantly lower on 9.4% THC cannabis (score 5.4 out of 10) than on 0% THC cannabis (6.1 out of 10) (p=0.023). However, no other comparisons between the different doses were statistically significant.

Participants using 9.4% THC cannabis reported finding it easier to fall asleep and had better quality of sleep than those taking 0% THC. No differences in mood or quality of life were seen with the different THC potencies.

Of the reported side effects, none were serious or unexpected. The most frequent side effects reported by participants when taking 9.4% THC cannabis were headache, dry eyes, burning sensation, dizziness, numbness and cough. Feeling “high” and euphoric was reported once in the 2.5%, 6% and 9.4% THC cannabis treatment periods.

 

How did the researchers interpret the results?

The researchers said that the 25mg herbal cannabis with 9.4% THC, administered as a single smoked inhalation three times a day for five days, significantly reduced average pain intensity compared to placebo in adults with chronic post-traumatic or post-surgical neuropathic pain. They also said that there were improvements in measures of sleep quality, but that long-term safety and efficacy studies are needed.

 

Conclusion

This placebo-controlled trial found that cannabis containing 9.4% THC could reduce neuropathic pain compared to the placebo. However, this was a small trial with only 23 participants, so it is difficult to tell whether these results demonstrate a real association, or if they are due to chance. A much larger trial would be needed for a longer period to assess the long-term outcomes of such a treatment. Additionally there are health concerns related to the use of smoked cannabis, including mental health problems and lung damage. Further research is needed to assess such potential side effects over the long term.

The researchers say that their study provides a way of looking at the short-term effects of smoked cannabis in a placebo-controlled trial. It is important to point out that cannabis is a class B drug, which is illegal to possess or supply, and is not licensed in any form for medical use.

Links To The Headlines

Cannabis may relieve chronic nerve pain. BBC News, August 30 2010

Smoking cannabis ‘alleviates pain and depression’. The Daily Telegraph, August 30 2010

 

Links To Science

Ware MA, Wang T, Shapiro S, et al. Smoked cannabis for chronic neuropathic pain: a randomized controlled trial. Canadian Medical Association Journal 2010, Published online ahead of print August 30

The lives of 10,000 patients could be saved each year by a “breakthrough pill”, according to the Daily Express.

The news story comes from a study that looked at whether a drug called ivabradine could help prevent deaths or hospital admissions due to chronic heart failure. This relatively common condition occurs when the heart is no longer able to pump enough blood to meet the demands of the body. The study found that over an average of 23 months, patients taking the drug experienced fewer cardiovascular deaths or hospital admissions with worsening heart failure than people taking an inactive placebo pill.

Ivabradine is a drug that lowers the heart rate and is already prescribed for some people with angina. The results of this large, multinational study demonstrate that heart rate reduction could improve the outcome for people with chronic heart failure. However, as the authors note, its results only apply to patients with a certain type of chronic heart failure that meets specific criteria. It cannot be assumed that these results apply to all patients with chronic heart failure.

 

Where did the story come from?

The study was carried out by researchers from a number of centres in Europe and the US, including the University of Gothenburg, Sweden. It was funded by Servier, a French pharmaceutical company, which was also responsible for the study’s data management and final data analysis (although these were verified by an independent statistical centre). It was published in the peer-reviewed medical journal The Lancet.

The study was widely covered by the media, and reports featured quotes from experts that suggested the drug could save 10,000 lives a year.  It is unclear how this figure was reached. The study itself calculated that 26 patients would need treatment for one year to prevent one cardiovascular death or one hospital admission for worsening heart failure (the main outcomes of the study). The BBC’s headline that the drug may ‘prevent’ heart failure is misleading.

 

What kind of research was this?

This randomised controlled trial, in which both the researchers and participants were blinded, investigated whether the drug ivabradine had any effect on cardiovascular outcomes, symptoms and quality of life in patients with heart failure when used in addition to standard treatment. This kind of trial, in which patients are randomly assigned to either an active treatment or a placebo, is the best way to find out about the effects of medical treatments.

The researchers say that chronic heart failure, which affects 2-3% of the population in many industrialised countries, has a fairly poor prognosis and that the development of new medicines to treat it is crucial. In chronic heart failure, the heart is unable to pump enough blood around the body.  The researchers say that reducing the heart rate could be particularly important in improving some types of chronic heart failure. This is because a lower heart rate would allow more blood to enter the chambers of the heart between each beat and reduce the effect of low blood supply to the heart muscle.

The benefits of one standard treatment for heart failure, called beta-blockers, seem to be linked in part to its heart rate-lowering properties. However, beta-blockers can have undesirable effects for heart failure patients. Ivabradine, say the researchers, seems to reduce heart rate without these side effects on the heart. It is currently licensed for use in people with angina who have a normal, regular heartbeat (sinus rhythm), either in combination with a beta-blocker or without if a beta-blocker is unsuitable or not tolerated.

 

What did the research involve?

The study was undertaken in 677 medical centres in 37 countries. Researchers enrolled 6,558 patients with moderate to severe heart failure associated with left ventricular systolic dysfunction (where contraction of the lower left heart chamber pumps an inadequate amount of blood to the rest of the body). The patients had to meet various other selection criteria, including being on stable background treatment and having a resting heart rate of at least 70 beats a minute.

Between October 2006 and June 2009, the patients were randomly assigned to receive either ivabradine or an inactive placebo drug. Both groups continued to take their standard heart failure medications, including beta-blockers. Neither patients nor researchers knew which patients were in which group. The dose of ivabradine was started at 5mg twice a day and was increased (up to a maximum dose of 7.5 mg twice a day) or decreased according to the change in each patient’s heart rate.

The patients were followed up for an average of 22.9 months. Researchers looked primarily at the “combined outcome” of cardiovascular death or admission to hospital with worsening heart failure (i.e. the occurrence of either or both outcomes). They also separately looked at a number of secondary outcomes, including deaths from any cause and all hospital admissions. All the results were analysed using standard statistical methods.

 

What were the basic results?

A small number of patients were removed from the study due to various problems. After these exclusions, final results were available for 3,241 patients in the ivabradine group and 3,264 patients in the placebo group. The main results were as follows:

• 24% of patients taking ivabradine experienced cardiovascular death and/or admission to hospital because of worsening heart failure, compared to 29% of those taking placebo (an 18% reduction in risk, hazard ratio [HR] 0.82, 95% confidence interval [CI] 0.75 to 0.90).
• When the results were analysed separately, 16% of patients taking ivabradine were admitted to hospital with worsening heart failure, compared to 21% taking a placebo (a 26% risk reduction, HR 0.74, 95% CI 0.66 to 0.83).
• 3% of patients on ivabradine died of heart failure, compared with 5% taking a placebo (a 26% risk reduction, HR 0.74, 95% CI 0.58 to 0.94).

Adverse effects were also examined:

• 5% of ivabradine patients had bradycardia (an abnormally low heart rate) compared to 1% of the placebo group.
• 3% of patients on ivabradine had blurred vision compared to 1% of the placebo group.
• 21% of patients on ivabradine withdrew from the study compared to 19% of patients on the placebo.

The researchers note that the overall effects of ivabradine were less marked in patients taking at least 50% of a standard dose of beta-blockers.

 

How did the researchers interpret the results?

The researchers concluded that ivabradine significantly reduced the major risks associated with heart failure when added to standard treatments. They also said the findings suggest that those with higher heart rates will benefit most.

Treatment with ivabradine was also associated with a reduction in heart rate of 15 beats a minute. Heart rate is an important physical factor that contributes to heart failure and reducing it can interrupt progression of the disease, the study authors suggest.

 

Conclusion

This large, well-conducted study has demonstrated the role that heart rate reduction may have in improving outcomes of people with heart failure. It found that the drug ivabradine, which slows heart rate, significantly reduced cardiovascular deaths and hospital admissions due to heart failure when combined with standard treatments.

The findings of this research could have implications for the treatment of some, but not all, patients with heart failure. As the researchers note, its results apply to a specific group of patients with both a stable, regular baseline heart rate of at least 70 beats a minute and left ventricular systolic function (an enlargement of the lower left chamber of the heart that means it is unable to pump enough oxygenated blood to the rest of the body). People with irregular heartbeat patterns, such as atrial fibrillation or flutter, were also excluded from the study. Overall, the effect of ivabradine in this trial cannot be said to be applicable to everyone with chronic heart failure.

It is also important to note that the results were achieved alongside the patients’ existing treatment programmes, which included beta-blockers, so no conclusions can be drawn about the effects of ivabradine in the absence of these drugs or as a replacement for them. As the researchers also point out, in many cases the recommended target doses of these other standard heart failure medications had not been reached, so it is not known whether this particular population would have been able to tolerate high doses of a beta-blocker.

Overall, the research supports the potential beneficial role of ivabradine in particular subgroups of people with heart failure.

Links To The Headlines

Ivabradine pill may prevent heart failure for thousands. BBC News, 29 August 2010

Cheap heart-failure drug could save thousands of lives. The Daily Telegraph, 29 August 2010

Pill for chest pains ‘could save 10,000 lives a year’. The Guardian, 29 August 2010

£10 heart pill could save 10,000 UK lives. The Sun, 29 August 2010

Thousands in heart drug boost. Daily Express, 29 August 2010

Links To Science

Swedberg K, Komajda M, Böhm M et al. Ivabradine and outcomes in chronic heart failure (SHIFT): a randomised placebo-controlled study. The Lancet, Early Online Publication, 29 August 2010