Predictors of Blood Pressure Control and Associations With Cardiovascular Diseases in Individuals With High Blood Pressure: a CALIBER Study

Study Overview
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Brief Summary
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Current guidelines for the clinical management of hypertension in adults recommend to achieve and maintain blood pressure levels of <140/90 mmHg. However, it is uncertain what proportion of individuals identified with high blood pressure in primary care actually reach blood pressure control, what factors are associated with attainment of control and to what extent blood pressure control attainment is associated with cardiovascular diseases in a contemporary population of individuals diagnosed with high blood pressure. The aim of this study is to investigate the extent to which patients achieve blood pressure control and associated risk factors, time to attainment of blood pressure control and whether this time is associated with an increased risk of CVD onset, all-cause and cardiovascular disease and end-stage renal disease.

Detailed Description
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An increment of 20 mmHg of systolic blood pressure (or approximately equivalent 10 mmHg diastolic blood pressure) is associated with more than a two-fold increase in risk of fatal stroke, and with a two-fold increase in fatal ischemic heart diseases in individuals aged 40-69 years. The management and control of high blood pressure is therefore one of the most important components of primary and secondary strategies for prevention of cardiovascular mortality and morbidity. Current guidelines for the clinical management of hypertension in adults recommend to achieve and maintain blood pressure levels of <140/90 mmHg. However, it is uncertain what proportion of individuals identified with high blood pressure in primary care actually reach blood pressure control, what factors are associated with attainment of control and to what extent blood pressure control attainment is associated with cardiovascular diseases in a contemporary population of individuals diagnosed with high blood pressure. This is important for clinicians and policy decision makers in order to design and implement effective strategies for patient management. The aim of this study is to investigate the extent to which patients achieve blood pressure control and associated risk factors, time to attainment of blood pressure control and whether this time is associated with an increased risk of CVD onset, all-cause and cardiovascular disease and end-stage renal disease. The study will use data from the CALIBER data set of clinically collected electronic health record data from England. This study is part of the CALIBER (Cardiovascular disease research using linked bespoke studies and electronic records) programme funded over 5 years from the National Institute for Health Research (NIHR) and Wellcome Trust. The central theme of the CALIBER research is linkage of the Myocardial Ischaemia National Audit Project (MINAP) with primary care (Clinical Practice Research Datalink - CPRD) and other resources. The overarching aim of CALIBER is to better understand the aetiology and prognosis of specific coronary phenotypes across a range of causal domains, particularly where electronic records provide a contribution beyond traditional studies. CALIBER has received both Ethics approval (ref 09/H0810/16) and ECC approval (ref ECC 2-06(b)/2009 CALIBER data set).

Official Title
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Predictors of Blood Pressure Control and Associations With Cardiovascular Diseases in Individuals With High Blood Pressure: a CALIBER Study

Conditions
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Stroke, Myocardial Infarction, Stable Angina Pectoris, Heart Failure

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients aged 18 and over Registered with a participating general practice during the study period Minimum one year of records prior to study entry meeting CPRD data quality Diagnosed with high blood pressure in the period January 1997 - March 2010 Exclusion Criteria: Patients without record of gender Patients with prior atherosclerotic disease, as recorded in primary care or hospitalisation data Patients with less than 6 months of follow-up since diagnosis of high blood pressure

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| BP control reached<br>Patients diagnosed with high blood pressure who lowered their blood pressure measurements during follow-up to <140/90mmHg if aged less than 60 years old, and <150/90mmHg for those of ≥60 years | |
| BP control not reached<br>Patients diagnosed with high blood pressure who did not lower their blood pressure measurement during follow-up (measurements were ≥140/90mmHg for individuals aged less than 60 years old, and ≥150/90mmHg for those of ≥60 years) | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| First presentation of cardiovascular disease | First recorded diagnosis of cardiovascular disease during follow-up: myocardial infarction, stroke (haemorrhagic or ischemic), heart failure, coronary revascularisation | 10 years | 
| All-cause mortality | Recorded death of any cause during follow-up | 10 years | 
| Cardiovascular mortality | Recorded death due to cardiovascular disease during follow-up | 10 years | 
| Risk factors for blood pressure control | Investigation of baseline factors associated with blood pressure control attainment during follow-up | 10 years | 
| Coronary revascularisation | First recorded percutaneous coronary intervention or coronary artery bypass graft (excluding interventions performed within 30 days before or after a diagnosis of myocardial infarction) | 10 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| First presentation of cardiovascular disease | First recorded diagnosis of cardiovascular disease during follow-up: stable angina pectoris and atrial fibrillation | 10 years | 
| End-stage renal disease | Recorded kidney disease resulting in dialysis or kidney transplantation during follow-up | 10 years | 
| Management of high blood pressure | Description of patient management in the 6 months after diagnosis of high blood pressure in terms of: blood pressure lowering medication start, timing and class; smoking cessation; dietary advice; physical activity; weight and total cholesterol decrease; and HDL-cholesterol increase | 6 months after cohort entry |