Mapping the prevalence of Chronic Venous Disease in England

Date of Approval: 
2020-09-04 00:00:00
Lay Summary: 
Chronic venous disease (CVD) describes enlarged veins, swelling and ulcers in the legs. These cause pain, stop people from working, and can cause isolation and low mood. Enlarged veins may affect up to one third of the population and leg ulcers up to 2%. CVD is expensive to treat, costing healthcare services up to £2.7 billion every year. There is no recent information on the number of people affected by CVD in England. There is also little information on the factors that contribute to the development and worsening of the disease. Some of these factors may increase the risk of patients developing CVD in the future. This study aims to: 1. Measure the number of CVD patients: a. With different disease stages, b. In different geographical regions, c. In different social and financial groupings, d. At different time periods over the last 10 years. 2. Explore what factors impact the development of CVD, factors might include: a. Person related characteristics e.g. age, gender, other medical conditions, ethnicity, smoking, weight and family history. b. Living characteristics e.g. region of residence, social or financial inequalities. 3. Explore whether any of these factors are associated with worsening of CVD after it has developed. Understanding the number of people affected by the disease can help ensure that the right care is available for existing and future CVD patients. Understanding what factors are associated with the development and worsening of CVD can help to lower the human and financial costs of the disease.
Technical Summary: 
Manifestations of CVD are classified using Clinical, Aetiology, Anatomic, Pathophysiology (CEAP) stages. This retrospective population-based cohort study aims to: 1. Estimate the overall annual period prevalence of CVD and the prevalence of each CEAP stage, for different geographical regions, over a ten-year period (1st June 2008 – 31st May 2018) 2. Explore factors associated with the development of CVD across different, age, gender and CEAP stages. 3. Explore factors that contribute to the progression of CVD. Study population: The overall study population is all adult patients with at least one year prior Up to Standard registration in CPRD within each 12-month period over the 10-year interval. Codes corresponding to different CVD CEAP stages will be used to define the CVD cohort. An age and gender matched control group, with no prior CVD code, will be randomly selected from the study population. Patients with serial CVD codes over the 10-year period will be used to evaluate CVD progression to different CEAP stages. Prevalence: A period prevalence will be calculated annually in the 10-year interval for overall CVD prevalence and prevalence at each CEAP stage. Prevalence will be stratified to geographical regions and deprivation levels. Prevalence trends over the 10-year interval will be measured. CVD and progression risk factor analysis: Four patient cohorts will be defined from the study population: CVD patients, a non-CVD control group, CVD patients with slow/ no progression and CVD patients with high speed progression. Descriptive statistics will be used to describe demographic, lifestyle and clinical characteristics of these different cohorts. Using these patient cohorts, multi-variate regression modelling will be used to evaluate risk factors for the development and progression of CVD. These will be adjusted for age, gender and other confounding factors such as treatment interventions. A marginal structures model will be used to evaluate time dependent covariates.
Health Outcomes to be Measured: 
Prevalence of CVD: Overall CVD prevalence and prevalence in different severity groups according to the CEAP severity stages will be measured. Prevalence of CVD in geographical and socioeconomic groups: Geographical region will be measured using region specific patient demographic information in CPRD. Social deprivation will be measured using Patient Level Index of Multiple Deprivation in CPRD. Patient characteristics, and possible risk factors to be evaluated, include age, gender, body mass index (BMI), ethnicity, personal history of venous thromboembolism (VTE) or superficial vein thrombosis (SVT), family history of CVD, smoking status, alcohol consumption, occupation, constipation (or low fibre intake), high systolic blood pressure, history of previous surgery at the site of venous disease, socioeconomic deprivation and depression, and for women parity, hormonal treatments and menopause. These risk factors will either be identified through specific CPRD patient demographic information or through separate Read codes. Progression of CVD: Progression/deterioration of CVD will be defined as a patient moving from a lower CEAP stage to a higher CEAP stage over time e.g. (C2 to C3, C3 to C4, C4 to C5/6, C2 to C4, C2 to C5/6, C3 to C5/6). Codes for each of these stages have been identified. Patients with no progression or low stage progression e.g. (C2 to C3, C3 to C4, C4 to C5/6) will be compared to patients with high levels of progression e.g. (C2 to C4, C2 to C5/6, C3 to C5/6). Patient with high speed CVD progression (progression in less than 5 years) will be compared to those with low speed of progression (progression in more than 5 years).
Application Number: 

Alun Davies - Chief Investigator - Imperial College London
Safa Salim - Corresponding Applicant - Imperial College London
Alun Davies - Collaborator - Imperial College London
Azeem Majeed - Collaborator - Imperial College London
Mahsa Mazidi - Collaborator - Imperial College London
Roberto Fernandez-Crespo - Collaborator - Imperial College London
Sarah Onida - Collaborator - Imperial College London

Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation