Prescription of blood pressure lowering and lipid lowering treatment in the UK and New Zealand: a cross sectional study

Date of Approval: 
2021-06-10 00:00:00
Lay Summary: 
The UK has well established guidelines for recommending statins and blood pressure lowering drugs to patients to reduce the risk of heart attacks and strokes. Statins are recommended to patients who are at high risk of heart attacks and strokes. Blood pressure lowering drugs are recommended based on both a patient’s blood pressure and their risk of heart attacks and strokes. GPs use the guideline recommendations, their own judgement, and discussions with the patient to decide on treatment. For example, when considering whether to prescribe blood pressure drugs, GPs will take into account not only the broad national guidelines but also (i) the risk of reducing blood pressure too much, which may lead to dizziness and falls, (ii) the risk of kidney disease, heart failure and stroke if a patient is not treated, and (iii) patient choice. Therefore, there are likely to be differences in the ways that the same patient would be treated across different GPs within the UK. This study aims to determine whether the right patients are receiving treatment and whether there are groups of patients who are not receiving treatment when they should be. It will also show how the coronavirus pandemic has affected treatment. Results will be compared to a similar study from New Zealand, where guidelines are the same for statins but different for blood pressure. Performing comparisons between countries with different guidelines will help us understand whether differences in guidance affect the way statins and blood pressure-lowering drugs are used in practice.
Technical Summary: 
Background The UK has well established guidelines for the management of cardiovascular disease risk factors. Lipid lowering treatment is recommended based on predicted absolute cardiovascular disease risk. Blood pressure lowering treatment is recommended largely on the basis of blood pressure cut-offs. Each GP is advised to combine guideline recommendations, clinical judgement and shared decision making with the patient to decide upon treatment. Adherence to guidelines therefore depends on a multitude of GP and patient factors. Aim The overall aim of this study is to examine the prevalence of prescriptions for blood pressure lowering treatment and lipid lowering treatment, and to identify missed opportunities and inequalities in care. The study will also evaluate the impact of the UK coronavirus pandemic on prescriptions. Methods Initially, using a cross sectional study of patients registered in a CPRD Aurum practice on 1st July 2019, this study will describe use of blood pressure lowering and lipid lowering medications on the study date, stratified by individual cardiovascular disease risk factors and predicted ten year risk of cardiovascular disease. Univariate logistic regression models will be used to determine the crude association of each risk factor with prescriptions. We will investigate whether prescribing is guideline compliant and assess inequalities by age, sex, ethnicity and socioeconomic status. Analyses will be repeated in 2020 and 2021 to examine the impact of the pandemic on prescribing. These analyses will determine whether the right patients are receiving treatment. This CPRD study will be compared to similar analyses using data from New Zealand. The UK and New Zealand provide a useful comparison in settings due to their disparate blood pressure but similar lipid lowering guidelines. These analyses will enable us to understand whether GPs tend to use risk to guide treatment decisions, and to what extent differences in guidance influence treatment decisions.
Health Outcomes to be Measured: 
The outcomes will be prescription of: • blood pressure lowering medications, and • lipid lowering medications on the study date (1st July 2019), including incident prescriptions on study date and prevalent prescriptions (i.e. those made prior to the study date whose duration overlaps with the study date, e.g. a prescription for three months of drugs made up to three months prior to study date). The repeated analyses in 2020 and 2021 will ascertain the same outcomes on 1st July 2020 and 1st July 2021.
Application Number: 
20_000165
Collaborators: 

Emily Herrett - Chief Investigator - London School of Hygiene & Tropical Medicine ( LSHTM )
Emily Herrett - Corresponding Applicant - London School of Hygiene & Tropical Medicine ( LSHTM )
Elizabeth Williamson - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Helen Strongman - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Krishnan Bhaskaran - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Laurie Tomlinson - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Rod Jackson - Collaborator - University of Auckland
Sue Wells - Collaborator - University of Auckland

Linkages: 
Patient Level Townsend Score