Award Title: A risk-based approach to blood pressure for cardiovascular disease prevention
Funder: Department of Health and Social Care

Abstract: Background: Although rates of cardiovascular disease have fallen dramatically in recent years, it remains the leading cause of death among men and second leading cause among women in the UK. In UK primary care, patients at risk of disease are routinely identified using cardiovascular disease risk scores, such as QRISK2, which incorporate a number of factors to predict absolute risk of disease over the next ten years. NICE guidelines advocate drug treatment of two main cardiovascular disease risk factors as the focus of the primary preventive strategy in the UK: cholesterol and blood pressure. Eligibility for cholesterol lowering drug treatment is determined by cardiovascular risk, as predicted by QRISK2, rather than levels of cholesterol. Conversely, eligibility for blood pressure lowering drug treatment is determined by a threshold of blood pressure, despite a growing body of international evidence in favour of using cardiovascular risk. A risk-based approach to blood pressure lowering could improve risk stratification and identify those most in need of treatment, and has already been adopted in New Zealand. However, this approach has not yet been adopted in the UK, perhaps due to uncertainties over the overall clinical benefits and harms in the NHS. The research proposed here will address these gaps in knowledge using routinely collected data from the UK NHS and New Zealand.Aim: To prevent cardiovascular disease events through the management of blood pressure reduction by cardiovascular disease risk. Question to be addressed: What would be the impact on patient and population health if blood pressure were managed based on cardiovascular disease risk, rather than the current blood pressure threshold-based approach? Plan of investigation: A range of epidemiological studies will be undertaken to investigate the impact of changing the UK's blood pressure lowering guideline from a blood pressure threshold-based approach to a cardiovascular disease risk-based approach. Two electronic health record sources will be used: (i) the Clinical Practice Research Datalink in the UK, a database holding the longitudinal primary care records of over 4 million current patients, and (ii) PREDICT from New Zealand, a database of over 400,000 patients holding cardiovascular risk factor data and linked to hospitalisation and mortality data.The first study will use CPRD data to quantify and describe the characteristics of patients in the UK who are eligible for blood pressure lowering under the current guideline and compare this to those eligible under a risk-based approach to treatment. The second will use models developed within CPRD data to compare the number of cardiovascular disease events occurring under each approach. The third study will estimate the risk of adverse events resulting from over- or under-treatment with blood pressure lowering, among the groups whose eligibility for treatment would change under a risk-based approach. This will use complementary data from the CPRD and PREDICT. Finally, using PREDICT data, GP and patient adherence to a risk-based guideline will be assessed. Summary of potential benefits to patients and NHS: The analyses planned in this proposal are the first steps in assessing whether a risk-based approach to management of blood pressure would be beneficial for patient and population health in the UK. If the approach resulted in a net decrease in the expected number of cardiovascular disease events, with minimal adverse effects, then NICE should consider recommending this approach in the NHS. This would be beneficial for patient health and would be relevant to a large proportion of the population with high blood pressure or high cardiovascular disease risk. It may also signify important cost savings to the NHS, for which a full cost-effectiveness study would be required.

Lay Abstract: Although rates of heart attacks and strokes have fallen dramatically in recent years, they remain among the leading causes of death in men and women in the UK. General practitioners identify patients at risk of disease using cardiovascular disease risk scores, which incorporate a number of factors (age, blood pressure, cholesterol, smoking, etc) to predict a person's risk of disease over the next ten years. UK guidelines recommend drug treatment of cholesterol and blood pressure to prevent heart attacks and strokes. Eligibility for cholesterol lowering drug treatment is determined based on a patient's overall disease risk, rather than their cholesterol level. But eligibility for blood pressure lowering drug treatment is determined based on blood pressure itself, even though there is evidence from other countries showing that using a patient's overall disease risk might be better at identifying people most in need of treatment, could reduce the number of heart attacks and strokes, and save money. Using a patient's overall disease risk to guide blood pressure lowering drug treatment is already done in New Zealand. However, this approach has not yet been adopted in the UK because the benefits and risks in the NHS have not been investigated. Given the benefits shown in other countries, it is now crucial to examine the impact of this alternative approach to blood pressure lowering treatment within the NHS and ask whether such an approach would benefit patients in the UK.The aim of this research is therefore to investigate whether managing blood pressure according to a patient's overall cardiovascular disease risk may be more beneficial to patient and public health in the UK than managing based on blood pressure alone. A range of studies will investigate the risks and benefits of managing blood pressure based on cardiovascular risk. Using the largest primary care data source in the UK, this investigation will estimate the number of patients who would be affected by a change in the strategy to manage blood pressure, and the number of heart attacks and strokes that would be expected compared to the current strategy. Given the current UK strategy, data from the UK are not sufficient to measure the harms of a risk-based approach. To ensure that these harms are properly addressed, data will also be used from a setting where blood pressure is already managed according to risk (New Zealand). Possible adverse effects include eye, kidney and heart damage due to untreated high blood pressure, and falls or fractures caused by blood pressures that become too low. Data from New Zealand will also be used to measure whether doctors and patients follow the risk-based approach, which will inform development of a strategy for the UK.Patients from the British Heart Foundation and the Farr Institute's Patient Working Group have discussed the study and contributed to the aims of this research. Their involvement has been central to the development of this application and their participation will continue to influence the investigation. Importantly, these patients will comment on the focus and disease outcomes of the studies, and on materials for distribution to patient groups at the end of the study. The results of these studies will be published in peer-reviewed scientific journals, presented at national and international conferences, and will be considered when the UK blood pressure lowering guidelines are reviewed. Results will be presented to patients and GPs, who will help to develop appropriate materials for distribution to charities and patient groups. These analyses will answer questions relating to a potentially life-saving and cost-saving new approach to the management of blood pressure and could inform the next steps towards implementation of a risk-based approach.

Research Activity Codes: 7.3 MANAGEMENT AND DECISION MAKING
Health Categories: CARDIOVASCULAR