Epidemiology of Heart Failure

Demographic Distribution

HF is a disease of older adults. In a recent population-based report from the United Kingdom, mean age at diagnosis was 76.7±12.6 years. A similar median age (76–77 years) at HF diagnosis was reported for inpatients in Denmark, with most patients diagnosed between age 66 and 85. In Canada, although patients diagnosed in specialty clinics were slightly younger (median, 69 years) compared with general clinic outpatients (72 years), and those diagnosed in the emergency department (75 years) were younger compared with inpatients (77 years), the majority of cases in the population were diagnosed between ages 57 and 84.

Men and women are equally affected by HF. However, age at onset and type of HF affect sex predominance. In the United Kingdom, women accounted for 49.0% of new HF cases. A similar 1:1 sex ratio for new cases has been reported in the United States around the world. However, although higher rates of coronary artery disease in men lead to male preponderance in younger patients, susceptibility to diastolic dysfunction leads to a higher proportion of women affected by HF at older ages. Men are more likely to develop HF with reduced EF (HFrEF), whereas women are more prone to HF with preserved EF (HFpEF). In the United Kingdom, age at diagnosis in men was 74±13 years versus 79±12 years in women. A similar difference has been reported in Sweden. Finally, in large studies, HF appears to affect all races equally.

Comorbidities (see also Chapter 48 )

As a disease of older adults, HF is rarely encountered in isolation. More than 80% of patients have ≥2 concomitant chronic conditions, and most have ≥3. The most common are hypertension, ischemic heart disease, diabetes mellitus, cerebral and peripheral vascular disease, atrial fibrillation, chronic kidney disease, chronic obstructive lung disease, anemia, and depression. As average age at HF diagnosis increases over time, the number of comorbidities and medications in patients with HF increases as well. In the United Kingdom, the number of comorbidities in patients with HF increased from 3.4±1.9 in 2002 to 5.4±2.5 in 2014, and the percentage of patients with ≥3 additional conditions increased from 68% to 87%. In the US National Health and Nutrition Examination Survey (NHANES), the average number of prescription medications in patients with HF increased from 4.1 in 1988–1994 to 6.4 in 2003–2008. Overall, there is a shift from a model where HF was mainly a consequence of coronary artery disease with male preponderance toward a disease of older adults equally affecting both sexes and accompanied by a complex medical profile. Among the 493 older adults (age 70–79 years at inception) who developed HF in the Health, Aging, and Body Composition Study, 36.8% had no prior coronary artery disease.

Estimates and Trends

Most contemporary national health care databases in developed countries indicate that the age-standardized incidence of HF at the population level is declining, and that age-standardized prevalence of HF is increasing only slightly, the latter being probably the result of advances in HF therapeutics. However, because of population aging, the crude incidence remains high and the crude prevalence and number of patients with HF keeps increasing. Estimates vary according to the methods and definitions used. The population incidence of HF is currently estimated between 200 and 400 cases annually per 100,000 individuals in most developed countries, and the crude prevalence ranges between 1% and 3%. Table 18.1 summarizes the population prevalence of HF in health care databases around the world.

In a comprehensive epidemiologic study from the United Kingdom, the population-based incidence of HF in 2014 was 332/100,000 person-years, a 7% decline from 2002; the decline was similar for men and women. Despite this decline, crude incidence increased by 2% and the number of new HF cases increased by 12% between 2002 and 2014, largely due to an increase in population size and age. In the same study, although the age- and sex-standardized prevalence of HF increased only slightly from 1.5% to 1.6%, the number of patients with HF increased by 23% over the same period.

Similar trends have been reported in North America and continental Europe. In a study of 2.3 million Medicare beneficiaries (age ≥65), although incident HF declined by 32% between 2004 and 2013, prevalence increased from 16.2% to 17.2%. In Olmsted County, Minnesota, the adjusted incidence of HF declined from 316/100,000 in 2000 to 219/100,000 in 2010. The decline was greater for HFrEF than for HFpEF. In Ontario, Canada, HF incidence decreased by 32.7% between 1997 and 2007 (from 455 to 306/100,000 person-years), with a comparable decrease in both inpatient and outpatient settings. In Sweden, despite a relative decline in incidence by 24% between 2006 and 2010 (average, 380 cases per 100,000 person years), the prevalence of HF remained unchanged. In Germany, the age- and sex-standardized incidence of HF in 2006 was 270/100,000 person years. In Italy, the incidence of hospitalized new HF cases in Lombardy decreased between 2005 and 2012 (from 362 to 313/100,000 adults), but with an increasing proportion of patients aged ≥85 years. However, in a study of in-hospital new HF cases in Denmark between 1995 and 2012, although HF incidence declined overall and in older persons (>50 years), there was an increasing trend in younger (≤50 years) persons.

Impact of Demographics and Socioeconomic Status

Age

Age is a major contributor to development of HF, and therefore the incidence and prevalence of HF is considerably higher among middle-aged or older adults. In a meta-analysis of community-based studies, the median prevalence of HF among persons age ≥60 was 11.8% (4.7%–13.3%). The effect of age on HF prevalence is demonstrated in the NHANES data ( Fig. 18.1 ). Among Danish adults, the annual incidence of new in-hospital HF diagnosis in 2012 was <0.01% in ages 18 to 35 but >1% in ages >74 ( Fig. 18.2 ) . In the United States, the annualized incidence of HF ranges between 1% and 2% among older adults (age ≥65), depending on age group and race.

Lifetime Risk of Heart Failure

In a project that pooled more than 700,000 person-years of follow-up in the United States (85% white, 15% black), lifetime risk for HF at age 45 was estimated at 30% to 42% in white men, 20% to 29% in black men, 32% to 39% in white women, and 24% to 46% in black women. Lifetime risk for HF was higher with higher blood pressure and body mass index (BMI) at all ages. Women are more likely to develop HF as the first manifestation of cardiovascular disease.

Prevalence of Preclinical (Stage A and B) Heart Failure

As with most chronic diseases, HF is a progressive condition amenable to early preventive interventions (see also Chapter 35 ) . To emphasize this concept, the American Heart Association and the American College of Cardiology have proposed a scheme that classifies HF into four stages. Stage A indicates the presence of risk factors but no clinical or subclinical disease. Stage B refers to asymptomatic cardiac structural or functional abnormalities usually detectable by cardiac imaging (i.e., subclinical disease). Stage C refers to stable symptomatic HF, whereas Stage D is used to indicate advanced symptomatic HF that is refractory to pharmacotherapy.

Because of the need for systematic imaging to detect subclinical disease, limited data exist on the population prevalence of HF stages. In the Atherosclerosis Risk in Communities (ARIC) study, among 6,118 participants age 67 to 91 years, 52% were categorized as Stage A and 30% as Stage B in the 2011–13 visit. In the Framingham study, among 6770 participants (54% women) with a mean age of 51, the prevalence of Stage A and B was 36.5% and 24.2%, respectively. The prevalence of Stage B increased steadily with age, from 17.6% in the ≤54 age group to 42.9% in the ≥75 age group ( Fig. 18.3 ) . Compared with healthy participants, mortality was twofold higher among participants with Stage B HF after a mean of 7 years.