Friday, 28 February 2014

Flu jab "may cut" stroke risk by a quarter

A recent report has revealed that people who have the seasonal flu jab are 24% less likely to suffer a stroke, according to The Daily Telegraph
The report is based on the results of a large study, which used the GP database for England and Wales to access data on almost 50,000 people who had suffered a stroke or transient ischaemic attack (TIA or a so-called “mini” stroke) over an eight-year period. Researchers then matched them to a person of the same age and gender who had attended the GP around the same time (these people are known as the “controls”). They then compared how likely they were to have been given the seasonal flu vaccine before the date of the stroke or TIA.
They found that slightly more controls had received the flu vaccine before the date: 50.8%, compared to 50.6% of people who had had a stroke or TIA. This meant that, overall, having the flu vaccine reduced the risk of a person having a stroke by about a quarter (there was no link with TIAs).
The research benefits from a large quantity of reliable data, with a number of health and lifestyle factors that may have influenced the results also adjusted.
It is plausible that a link exists between the protection against flu strains the vaccine provides and the risk of having a stroke.
The researchers summarise by saying they “reinforce current recommendations for annual influenza vaccination” with “potential added benefit for stroke prevention”.

Where did the story come from?

The study was carried out by researchers from the University of Lincoln and University of Nottingham, and was funded by the National Institute for Health Research.
The study was published in the peer reviewed journal Vaccine.
The Daily Telegraph and The Independent’s reporting of the study was accurate.

What kind of research was this?

This was a case-control study, which aimed to see if the influenza or pneumococcal vaccination might prevent a stroke. Some previous research studies have suggested that respiratory infections, such as the flu, may be associated with a stroke.
They cite a number of studies that have found there is an increased likelihood of respiratory symptoms in the weeks prior to having a stroke. However, other observational studies failed to find any significant link.
Due to this inconsistent evidence, the researchers aimed to investigate this further themselves, using data for thousands of people stored on the UK General Practice research database.
They identified people who had suffered a stroke or TIA and a matched group of people without, examining if they had been given the seasonal flu jab or the pneumococcal vaccine.
The pneumococcal vaccine is part of the child vaccination programme. It is also offered as a one-off jab to all adults over the age of 65 and to younger adults that have a heightened risk of infection (such as those with weakened immune systems). The vaccine protects them against infection with the bacteria Streptococcus pneumonia, which can cause pneumonia and other severe infections.

What did the research involve?

The researchers used the General Practice Research Database (now called the Clinical Practice Research Datalink, CPRD), which contains anonymised data for over 5% of the population of England and Wales. The database codes for vaccinations, diseases and health behaviours using a validated coding system. They used the eight-year period 2001-9 to identify adults coded for stroke or TIA (“case”). Each case was randomly matched to a control of the same age and gender who attended a general practice at the same time. They excluded cases and controls with a previous diagnosis of stroke or TIA.
They looked for vaccinations recorded prior to the ”index” date, when the stoke or TIA was recorded. Because the influenza vaccine is seasonal, the researchers looked to see if the vaccine was given in the same seasonal year (September 1 to August 31 the following year) and whether given “early” (between September 1 and November 15) or “late” (November 16 to February 28), and the time elapsed since last influenza vaccination (defined as 0 to 3, 3 to 6, 6 to 12, or more than 12 months before the index date). Pneumococcal vaccination was defined as vaccination at any time before the index date, as it is given as a one-off vaccine.
The researchers looked at the odds for cases and controls given either or both vaccines.
They adjusted their analyses for potential confounders, including cardiovascular risk factors, current medications, number of cormorbid medical illnesses, lifestyle factors (such as whether a person smokes) and the number of GP consultations and home visit requests. 

What were the basic results?

The researchers identified 47,011 cases (comprising 26,784 cases of stroke and 20,227 cases of TIA), with the same number of matched controls.
Very slightly more controls than cases had received the flu vaccine in the same season as the index date: 50.8% of controls compared to 50.6% of cases. After adjusting for the measured confounders, this meant that having an influenza vaccine within the same season as the index date was associated with a 24% reduction in the risk of a stroke (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.72 to 0.80).
Further adjustment for body mass index (BMI), cholesterol and blood pressure slightly reduced the risk association, such that the risk reduction was only 19%, but still remained statistically significant(OR 0.81, 95% CI 0.77 to 0.85).
Reduction in the risk of a stroke was greatest when the vaccine had been given within three months of the index date (22% reduction), reducing to 11% reduced risk when the vaccine had been given between three and 12 months of the index date.
However, the flu vaccine only seemed to protect against a stroke if given early in the flu season: September to mid-November (26% risk reduction, OR 0.74, 95% CI 0.70 to 0.78). Giving the vaccine late in the flu season (mid-November to February) did not result in a significantly reduced risk.
Flu vaccine was not significantly associated with being at risk of TIA. Neither was pneumococcal vaccination significantly associated with being at risk of a stroke or TIA.

How did the researchers interpret the results?

The researchers conclude that: “Influenza vaccination was associated with a 24% reduction in risk of having a stroke, but not TIA. Pneumococcal vaccination was not associated with reduced risk of a stroke or TIA. This has important implications for the potential benefits of an influenza vaccine.”


This research finds that, overall, having the flu vaccine reduced the risk of a person experiencing a stroke by about 25%. The reduction in risk seemed to be greatest within the first three months of vaccination, but remained for up to 12 months.  However, the effect lasted only if the vaccine was given early in the flu season (September to mid-November); giving the vaccine late in the flu season (mid-November to February) was not associated with significantly reduced risk.
The research benefits from using data coded within the General Practice Research Database for England and Wales for almost 50,000 people with stroke or TIA, matched by age and gender to the same number of controls who had attended the GP at the same time. There is still potential for missing or miscoded information in the database, but overall the data is thought to be fairly reliable.
They also adjusted their analyses for a large number of potential confounders. The researchers say there is still the potential for what they call “healthy vaccine” bias, with healthier people more likely to be vaccinated, and are perhaps less likely to have a stroke.
The findings support previous studies, which the researchers say have suggested an association between recent respiratory illness and risk of a stroke; they have also studied findings that influenza vaccination may offer protection against another heart attacks. However, the biological mechanisms by which respiratory infections or influenza might precipitate cardiovascular events is unknown. It is also unknown if the findings could apply to younger people at risk.
In summary, it is plausible that there could be a link between the protection the flu vaccine gives against flu strains and a risk of suffering a stroke in the same season.
The purpose of the seasonal influenza vaccine is to protect against respiratory illness, not to offer possible protection against a stroke. However, the researchers “reinforce current recommendations for annual influenza vaccination” and that there is “the potential added benefit of stroke prevention”.
Even if the link between the flu jab and reduced stroke risk is unproven, it is always a good idea to get the jab if you are in one of the groups recommended to receive it. This is if you are:
  • 65 years of age or over 
  • pregnant
  • have a long-term (chronic) medical condition such as asthma or diabetes
  • living in a long-stay residential care home or other long-stay care facility
  • receive a carer's allowance, or you are the main carer for an elderly or disabled person whose welfare may be at risk if you fall ill
  • a healthcare worker with direct patient contact or a social care worker
Analysis by Bazian. Edited by NHS Choices

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Links to the headlines

Flu jab could cut risk of stroke by quarter. The Daily Telegraph, February 20 2014

Links to the science

Siriwardena AN, Asghar Z, Coupland CA. Influenza and pneumococcal vaccination and risk of stroke or transient ischaemic attack—Matched case control study. Vaccine. Published online January 28 2014
reposted from:
crabsallover highlightskey pointscomments / links.

Saturday, 15 February 2014

Lipid modification : Cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease. NICE guideline: Draft for consultation, February 2014

reposted from:

(NB. full guidance: (not reviewed here))

My Key points (my highlights):-

  • [1.3.16] Offer atorvastatin 20 mg for the primary prevention of CVD. [new 2014] 
  • Use the QRISK2 risk assessment tool to assess CVD risk for the primary prevention of CVD. [new 2014] 
  • Prioritise people for a full formal risk assessment if their estimated 10-year risk of CVD is 10% or more. [2008, amended 2014] 
  • Use the QRISK2 risk assessment tool to assess CVD risk for the primary prevention of CVD. [new 2014] 
  • Further information and advice on healthy cooking methods can be found at NHS Choices. [new 2014] 
  • Before starting lipid modification therapy for the primary prevention of CVD, take at least 1 lipid sample to measure a full lipid profile. This should include measurement of total cholesterol, HDL cholesterol, non-HDL cholesterol, and triglyceride concentrations. A fasting sample is not needed. [new 2014] 
  • Use the clinical findings, lipid profile and family history to judge the likelihood of a familial lipid disorder rather than the use of strict lipid cut-off values alone. [new 2014] 
  • In this update the Guideline Development Group (GDG) recommend the use of non-high density lipoprotein (non-HDL) cholesterol rather than low density lipoprotein (LDL) cholesterol. LDL cholesterol is not directly measured but requires a calculation using a fasting sample and for triglyceride levels to be less than 4.5 mmol/litre, whereas the measurement of non-HDL does not. 
  • Follow-up of people initiated on statin treatment 
  • 1.3.29 Measure cholesterol, HDL cholesterol and non-HDL cholesterol in people who have been started on high-intensity statin treatment after 3 months of treatment and aim for a greater than 40% reduction in non-HDL cholesterol. If a greater than 40% reduction in non-HDL cholesterol is not achieved: 
    • discuss adherence and timing of dose (take at night) 
    • optimise adherence to diet and lifestyle measures 
    • consider increasing dose if started on less than atorvastatin 80 mg and person is judged to be at higher risk because of comorbidities, risk score or using clinical judgement. [new 2014] 
  • 1.3.38 Before offering a statin, ask the person if they have had persistent generalised unexplained muscle pain, whether associated or not with previous lipid-lowering therapy, and if present, measure creatine kinase levels. If these are elevated start statin treatment at a lower dose. [new 2014]
  • 1.3.42 Measure baseline liver transaminase enzymes (alanine aminotransferase or aspartate aminotransferase) before starting a statin. Measure liver transaminase (alanine aminotransferase or aspartate aminotransferase) within 3 months of starting treatment and at 12 months, but not again unless clinically indicated. [2008, amended 2014] 
  • 1.3.50 Tell people that there is no evidence that omega-3 fatty acid compounds help to prevent CVD. [new 2014] 
  • Combination therapy for preventing CVD 
    • 1.3.51 Do not offer the combination of a bile acid sequestrant (anion exchange resin), fibrate, nicotinic acid or omega-3 fatty acid compound with a statin for the prevention of CVD. [new 2014] 
  • Appendix B: Grouping of statins 
For the purpose of this guideline, statins are grouped into 3 different intensity categories according to the percentage reduction in low-density lipoprotein cholesterol (see table 1). This grouping was agreed by GDG consensus, informed by analyses in the literature. See the full guideline for a discussion of this grouping. 


Crabsallover Change in Statin Use

Switch from Simvastin 10mg/day = 27% reduction in low-density lipoprotein cholesterol, where low intensity = 20%-30%, to Atorvastatin 20mg/day = 43% high intensity (>40%). NB. Medium intensity (31%-40%)

NICE publishes new draft guidelines on statins use

crabsallover highlightskey pointscomments / links.

"Millions more people should be put on cholesterol-lowering statin drugs," BBC News reports. Draft guidance from the National Institute for Health and Care Excellence (NICE) has recommended that the drugs should be given to people with an estimated 1 in 10 or more risk of cardiovascular disease (CVD), which includes conditions such as heart disease and stroke.

At present, guidance for doctors on using statins to prevent CVD says that only people with a 20% or greater risk of developing CVD in the next 10 years should be offered the drugs.

NICE recommends that a specific statin called atorvastatin is used for both the prevention and treatment of CVD.

How is CVD risk assessed?

NICE recommends a risk assessment tool called QRISK2. This involves a series of calculations based on the following factors:

  • age
  • sex
  • body mass index (BMI)
  • ethnicity
  • family history of heart disease
  • whether you have one or more of the following chronic diseases: diabetes, kidney disease, high blood pressure, atrial fibrillation or rheumatoid arthritis
  • blood cholesterol levels
  • your current blood pressure

Doctors should offer "high-intensity" treatment with statins to healthy people who have a 10% or greater 10-year risk of developing CVD. "High-intensity" statins produce the largest LDL reduction at the lowest doses.

Healthy patients at risk of CVD should be offered 20mg of a drug called atorvastatin to cut the risk of CVD. In the previous guidelines, therapy was started using 40mg of a drug called simvastatin. Atorvastatin is a high-intensity drug, while simvastatin is medium intensity.

Where do the draft guidelines come from?
The updated draft guidelines have been published by NICE, the National Institute for Health and Care Excellence. They are a draft update of the guidelines on lowering cholesterol (or lipid modification) that were published in 2008.
These are draft guidelines that have been published for consultation with professional and government organisations, patient and carer groups, and companies. These stakeholders have until March 26 2014 to comment before NICE decides on its final recommendations.
Anyone who wishes to comment on the guidelines must first register as a stakeholder. To find out more, visit the NICE consultation page.

What is the rationale behind the new recommendations?
The recommended changes have been made on the basis of cost effectiveness. For example, NICE concluded that high-intensity treatment with 20mg atorvastatin is more cost effective than statin treatment using medium-intensity simvastatin.
It also reports that medium-intensity treatment is more cost effective compared with no treatment or low-intensity treatment at all realistic risk levels.
The guideline group decided to change the threshold from 20% risk to 10% risk by taking into account "the uncertainty regarding the frequency of adverse events in routine clinical practice, which may be higher than in clinical trials, the uncertainty around the magnitude of the effectiveness of statins and the accuracy of the QRISK2 tool itself, as well as the base case cost effectiveness results and sensitivity analyses".
The drugs have become cheaper in recent years, and their effectiveness is well proven, NICE notes.

The organisation has also pointed out that although death rates from CVD have halved since the 1970s and 1980s, CVD is the cause of one in three deaths in the UK. At present, as many as seven million people in the UK are believed to be on statins, at an estimated annual cost of £450 million.

What are the risks of taking statins?
Statins can have side effects, although the most common ones, while a nuisance, are not serious. They include stomach upset, headache and insomnia. Occasionally, the drugs can cause inflammation and damage to the muscles. Serious side effects, such as jaundice and visual disturbance, are rare.
Statins are not suitable for everyone. For example, they should not be taken if you have severe liver disease or blood tests suggest your liver may not be working properly.
Read more about the side effects of statins.

What can I do to cut the risk of CVD?
As NICE makes clear, statins are not the only option for treating high cholesterol. Alternative treatments include eating a healthy diet that is low in saturated fats, increasing the amount of omega-3 fatty acids in your diet, and other prescribed medications.
Professor Mark Baker, director of the Centre for Clinical Practice at NICE, said: "As well as taking statins, people with raised cholesterol levels and high blood pressure should reduce the amount of foods containing saturated fat they eat.
"They should exercise more and control their blood glucose levels by reducing their intake of sugar and by losing weight. They should also stop smoking."

Read more advice about lowering your cholesterol levels 
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links to the headlines

Further reading

References (accessed 15th February 2014)