Epidemiology of heart failure Darrel Francis Clinical Senior Lecturer in Cardiology Imperial College School of Medicine

Difficulties of case definition Aetiology Prevalence and Incidence Temporal trends Global burden

Case definition

The greatest challenge in the epidemiology of heart failure: difficulty defining cases Symptoms are protean Signs are commonly found in subjects without heart failure –Tachycardia, crepitations, leg oedema(!) Tests: what is normal? why is this a challenge?

Why are normal ranges so important here? After all, we can study blood pressure without predeciding normal range… BP is easier because there is only one way to measure it (or at least experts have developed conventions)

There is more than one “test” for heart failure! No tests, just symptoms + signs

Criterion Point value[*] Category I: history Rest dyspnea4 Orthopnea4 Paroxysmal nocturnal dyspnea3 Dyspnea while walking on level area2 Dyspnea while climbing1 Category II: physical examination Heart rate abnormality (1 point if 91 to 110 beats per 1 or 2 minute; 2 points if more than 110 beats per minute) Jugular venous elevation (2 points if greater than 2 or 3 6 cm H2O; 3 points if greater than 6 cm H2O plus hepatomegaly or edema) Lung crackles (1 point if basilar; 2 points if more than 1 or 2 basilar) Wheezing 3 Third heart sound 3 Category III: chest radiography Alveolar pulmonary edema 4 Interstitial pulmonary edema 3 Bilateral pleural effusion 3 Cardiothoracic ratio greater than Upper zone flow redistribution 2 8 to 12 points = definite HF 5 to 7 points = possible HF <4 points = unlikely HF from Marantz et al Circulation 1988;77: Boston Criteria for diagnosing Heart Failure

“No tests” gives very poor validity Less than half of those identified by clinical judgement alone are confirmed by subsequent tests Even more unreliable for women than for men

ESC gives guidelines for definition of HF Eur Heart J 2005; 26: 1115–1140.

There is more than one “test” for heart failure! No tests, just symptoms + signs Brain Natriuretic Peptide (blood test) Radionucleide ventriculography (MUGA) or contrast ventriculography 2d Echocardiography Magnetic Resonance Imaging Tissue Doppler Imaging

Impact of difficult case definition? Difficult to safely compare absolute rates beyond study –may be due to ascertainment method, not a true difference in the population Reasonably safe to look for relationships (e.g. with age) within any one study

Aetiology

Aetiology of heart failure in a UK population Coronary Artery Disease 52% Idiopathic 13% Valve Disease 10% Cardiomyopathy 10% Hypertension 4% Alcohol 4% Atrial Fibrillation 3% (Wood, 2002)

A more honest breakdown? Cowie, Hillingdon heart failure study, Eur Heart J 1999; 20: 421–428

Aetiology does change In the 1950’s, Hypertension was the commonest aetiology –Garrison GE, McDonough JR, Hames CG, Stulb SC. Prevalence of chronic congestive heart failure in the population of Evans County, Georgia. Am J Epidemiol 1966;83: Since then, primary prevention (antihypertensive therapy) has dramatically reduced this proportion –Kannel WB, Ho K, Thorn T. Changing epidemiological features of cardiac failure. Br Heart J 1994;72:S3-S9

Prevalence

Invited random sample (n=1617) of all men and women aged over 45 years registered at GP practices in the West Midlands. All patients who agreed to participate were assessed in their own general practice by clinical history (including prescribed drugs), determination of New York Heart Association functional class, clinical examination, resting 12 lead electrocardiography, and echocardiography including Doppler studies. Defined heart failure according to ESC criteria: appropriate symptoms (NYHA II or worse) plus objective evidence of cardiac dysfunction. EF<40%: "definitely impaired“ 40-50%: "borderline" (40-50%) Did not attempt to diagnose diastolic dysfunction. Case study: Heart of England Screening study Davis et al, BMJ 2002;325:

Heart of England Screening study Over 2% of patients (3% of men and 1.7% of women) screened had definite heart failure. Probable heart failure was seen in around a further 1% of patients. From these prevalence rates they estimate: about 369,000 men aged >45 in the UK with definite heart failure, and 300,000 women, giving a total of around 669,000. If probable cases of heart failure are included, there are an estimated 497,500 men and 404,000 women, a total of 901,500 people aged 45 and over who have heart failure in the UK today. Prevalence of heart failure increases steeply with age, so that while around 1% of men and women aged under 65 have heart failure, this increases to about 7% of those aged years and 15% of those aged 85 and above.

Potentially complex contributory factors

Does the “2%” prevalence cover all types of patient?

Prevalence of Congestive Heart Failure by Age and Sex NHANES: Source: CDC/NCHS and NHLBI.

Ellis C et al (2001) Health Statistics Quarterly 11: 17-24www.heartstats.org Prevalence of heart failure by deprivation, 1998, England and Wales

Temporal trends

Prevalence is rising…

Congestive Heart Failure Episodes by Sex United States: Source: CDC/NCHS.

Levy, NEJM 2002; 347: Why is prevalence rising?

Survival

Levy, NEJM 2002; 347:

MI Bladder Ca Prostate Ca Bowel Ca Heart Failure Lung Ca Months from diagnosis Survival % Stewart S, EJHF 2001; 3: Survival after diagnosis of cancer or heart disease Men:

Months from diagnosis Survival % MI Ovarian Ca Bowel Ca Heart Failure Lung Ca Survival after diagnosis of cancer or heart disease in women: Where does breast cancer lie? Breast Ca Breast cancer

Epidemiology of Heart failure Numbers heavily depend on methods –clinical assessment is unreliable Marked increase in prevalence with age Risk factors are similar to those of coronary artery disease Mortality worse than most cancers Increasing survival with modern therapy leads to increasing prevalence

Today a problem of the developed world, but…