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

Date of Approval
Application Number
20_000165
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.

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