Epidemiology of gout, its treatment and comorbidities - a prospective cohort study using data from Clinical Practice Research Datalink (CPRD)

Date of Approval: 
2021-06-10 00:00:00
Lay Summary: 
Gout is a common arthritis characterised by the presence of needle-shaped urate crystals inside the joints. Once shed, they cause a flare characterised by abrupt onset of pain, tenderness, and swelling. A study using data from the CPRD reported that the prevalence of gout in the UK increased dramatically between the mid-1990s and 2010, and that only one in three patients with gout were prescribed urate lowering medicine e.g. allopurinol in this period. Studies from other countries report that the prevalence of gout has not changed between 2010 and 2020. Currently, it is not known if the prevalence of gout has stabilised in the UK in recent years or if coverage with allopurinol has improved after the latest recommendations by the British Society of Rheumatology published in 2017. Additionally, gout associates with heart attack, stroke and deep vein thrombosis. However, it is not known if the risk of these illnesses is increased in the period soon after a gout flare. The purpose of this study is to assess whether the number of people with gout has increased in the UK in recent years, and to find out if more people with gout are being prescribed medicines such as allopurinol. We will also find out whether gout flares associate with heart attack, stroke or blood-clots in the veins or lungs in the short-term. As gout flares are characterised by severe inflammation, we believe that they will further increase the risk of these illnesses in the following time period.
Technical Summary: 
Objectives: [1] To examine the temporal trend in incidence and prevalence of gout between 1997-2020. [2] To examine the temporal trend in all-cause mortality and prevalence of urate lowering treatment (ULT) prescription in patients with gout between 1997-2020. [2] To examine the association between gout flares and (a) acute myocardial infarction, (b) stroke, (c) venous thromboembolism. Design: prospective cohort study with nested cross-sectional and case-control studies. Study period: 01/01/1997– 31/12/2020. Data sources: Clinical Practice Research Datalink, Hospital Episode Statistics, Office for National Statistics Methods: We will calculate the point prevalence of gout, and ULT prescription in people with gout on the 1st July of each year between 1997 and 2020. Participants in receipt of ULT prescription(s) in the 60 days preceding the 1st of July will be classified as prescribed ULT. Similarly, the annual incidence of gout between 1997 and 2020, and mortality rate of gout cases incident in each calendar year between 1997 and 2020 will be calculated. Join Point regression will be used to examine the temporal trends. The association between acute myocardial infarction, stroke, venous thromboembolism, and gout will be assessed using nested case-control study design. The nested case-control study will include controls that are age, sex and duration of registration in CPRD matched to cases, and adjusted for covariates including demographic factors, lifestyle factors, ULT, and comorbidities. Three nested case control studies will be performed, one for each outcome of interest. Conditional logistic regression will be used to examine associations. Adjusted OR, and 95% confidence intervals (CIs) will be calculated. Data management and analysis will be performed by STATA version 16.
Health Outcomes to be Measured: 
• Gout – incident and prevalent • Urate lowering treatment prescription • Death • Acute myocardial infarction • Acute stroke • Venous thromboembolism – defined as either deep vein thrombosis or pulmonary embolism,
Application Number: 
20_000233
Collaborators: 

Abhishek Abhishek - Chief Investigator - University of Nottingham
dalia Elmelegy - Corresponding Applicant - Nottingham University Hospitals
Anthony Avery - Collaborator - University of Nottingham
Georgina Nakafero - Collaborator - University of Nottingham
Laila Tata - Collaborator - University of Nottingham
Mamas Mamas - Collaborator - Keele University

Linkages: 
HES Admitted Patient Care;ONS Death Registration Data;Practice Level Index of Multiple Deprivation