One third of people who had a first stroke in the UK between 2009 and 2013 had known risk factors and were not taking the drugs that might have prevented their stroke.
Electronic general practice records from almost 30,000 people who had a stroke showed that about 60% had risk factors that meant they might have been eligible to take cholesterol-lowering, anti-clotting or blood pressure medication. But 54% of these people had no recent prescription for the appropriate drug(s).
The researchers estimate that almost 12,000 strokes a year in the UK could be prevented if everyone eligible for preventive drugs took them.
We don’t know the reasons why people weren’t prescribed these drugs. They might have had valid medical reasons for not taking them or have chosen not to take them against medical advice. The large scale of under-prescribing revealed in this study suggests a possible need for more systematic processes around identification and management of people with cardiovascular risk factors.
Why was this study needed?
There are an estimated 110,000 strokes each year in England. It’s one of the major causes of disability, and costs the NHS an estimated £2.8 billion in direct treatment costs.
Drugs to reduce blood pressure, cholesterol and the likelihood of blood clots could reduce the numbers of strokes. However, until now it has remained unclear how many people with risk factors for stroke are receiving the necessary drug treatment to reduce their risk.
This study aimed to find this out, by reviewing general practice data in an anonymous registry containing secure details on around 6% of the UK population. They aimed to estimate the number of strokes that might be prevented if everyone eligible for preventive medication actually took it.
What did this study do?
Researchers analysed information from The Health Improvement Network database, which holds anonymous electronic general practice records for 3.6 million UK patients. They identified everyone who had a first stroke or transient ischaemic attack (TIA) from January 2009 to December 2013.
They checked to see how many of these people had risk factors indicating a need for blood pressure (antihypertensive), cholesterol-lowering or anticlotting (anticoagulant) medication. If they had not been prescribed these drugs in the 90 days before stroke (120 days for anticoagulants), this was defined as under-prescribing.
The researchers looked for notes to explain why they were not taking the drugs, and whether they had a prescription that had stopped, or had never been prescribed them.
What did it find?
- Of the 29,043 people who had a first stroke during the study period, 17,680 (60.8%) had identifiable risk factors that meant they could have been eligible for one or more stroke prevention drug. Overall 9,579 of these people (54%) were not prescribed the necessary treatment.
- Of those eligible for cholesterol-lowering drugs, 52% did not have a recent prescription. A quarter of those eligible for antihypertensive drugs and 49% eligible for anticoagulant drugs did not have a prescription.
- Only 0.7% to 7% of patients had a reason for non-prescription of a preventive drug recorded in their notes.
- For anticoagulants and cholesterol-lowering drugs, people were more likely to have never had a prescription than to have had a previous prescription stopped for some reason. For antihypertensive drugs, a similar proportion of eligible people had the drug previously prescribed and then stopped as those who’d never had one prescribed.
- The researchers estimate that each year 41,405 people in the UK who have a first stroke may have been eligible for preventative treatment and not prescribed. They estimate that thousands of strokes every year could be prevented by increased prescribing in those with known risk factors.
What does current guidance say on this issue?
NICE 2016 guidelines on cardiovascular risk outline which people should have their risk, including the risk of stroke, assessed. It covers how this should be done, and the information and advice that people should be offered to reduce their cholesterol as a result of their risk assessment. NICE recommend that people who have not already had a stroke (i.e. primary prevention) or diabetes and with an estimated 10% risk of developing cardiovascular disease within 10 years should be offered a formal risk assessment and then treatment to reduce their cholesterol.
Other NICE guidelines cover the diagnosis and management of high blood pressure. These suggest that antihypertensive drug treatment is offered to people aged under 80 years with hypertension (without target organ damage or previous CVD or diabetes) who have a 10-year cardiovascular risk equivalent to 20% or greater.
The use of anticoagulants in people with atrial fibrillation and without previous stroke or TIA, is covered in other NICE guidance in 2014. These recommend considering or offering treatments to prevent stroke following the use of a scoring tool called CHA2DS2-VASc to assess risk of developing a stroke and an assessment of bleeding risk.
What are the implications?
Extrapolating the figures to the UK population suggests that many strokes could be prevented each year by appropriate prescribing of preventative medication.
However, we don’t know why people weren’t taking the medicines. Their GPs might have had sound clinical reasons for not prescribing them. Also, the study doesn’t tell us whether the people who were prescribed drugs were actually taking them, either.
But the scale of potential under-prescribing identified suggests that there may be room for improvement and perhaps more systematic processes around identification and management of people with cardiovascular risk factors.
Citation and Funding
Turner GM, Calvert M, Feltham MG, et al. Under-prescribing of Prevention Drugs and Primary Prevention of Stroke and Transient Ischaemic Attack in UK General Practice: A Retrospective Analysis. PLoS Med. 2016;13(11):e1002169
This project was funded by the National Institute for Health Research (NIHR) School for Primary Care Research (SPCR). TM was partly funded by the NIHR through the Collaborations for Leadership in Applied Health Research and Care for West Midlands (CLAHRC-WM).
NICE. Cardiovascular disease: risk assessment and reduction, including lipid modification. CG 181. London: National Institute of Health and Care Excellence; 2016
NICE. Hypertension: the clinical management of primary hypertension in adults. CG 127. London: National Institute of Health and Care Excellence; 2011.
NICE. Atrial fibrillation: the management of atrial fibrillation. Clinical Guideline 180. London: National Institute of Health and Care Excellence; 2014.
NICE. Stroke and transient ischaemic attack in over 16s: diagnosis and initial management. London: National Institute of Health and Care Excellence; 2008.
Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre