Based on data from the U.S. National Inpatient Sample, between 2001 and 2014 more than 57 million admissions occurred for ADHF as the primary or secondary diagnosis.² Approximately 25% of these admissions were caused by a primary HF diagnosis.² From 2001 to 2014, the rate of hospitalization for the primary diagnosis of HF declined 3% annually from 563/100,000 U.S. adults in 2001 to 398/100,000 U.S. adults in 2014.² This is in contrast to the rates of hospitalization for a secondary diagnosis of HF, which remained stable between 2010 and 2014 at approximately 1388/100,000 U.S. adults.² From 2013 to 2017, on the other hand, an increase in primary HF admissions was observed, including increases in crude rates of overall and unique patient hospitalizations (JAMA Cardiol. 2021 Feb 10;e207472. doi:10.1001/jamacardio.2020.7472, PMID: 33566058).). Owing to an expanding population, the absolute number of hospitalizations for ADHF is anticipated to increase.

Large HF registries such as the Acute Decompensated Heart Failure National Registry (ADHERE), Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure (OPTIMIZE-HF) and EuroHeart Failure Survey II (EHFS II) have helped to inform our understanding of ADHF. Registries have observed that new onset HF represents 12% to 37% of admissions while patients with a known HF history represent 63% to 88% of admissions.³,⁴,⁵ These registries have demonstrated that despite declining primary HF admissions, the proportion of admissions for HFpEF is increasing. Data from Olmstead County, Minnesota, observed that admissions for HFpEF relative to HFrEF increased at a rate of 1% per year from 1987 to 2001.⁶ Similarly, the Get With The Guidelines-Heart Failure (GWTG-HF) registry demonstrated that the proportion of patients hospitalized with ADHF and HFpEF increased from 33% in 2005 to 39%, and those with HFrEF decreased from 52% to 47% in 2010.⁷ Presently, the proportions of hospitalizations for ADHF with HFrEF versus HFpEF are roughly equivalent.⁸,⁹

ADHF is the most common cause of hospitalization for patients greater than or equal to 65 years, and about 75% of HF admissions occur in patients greater than or equal to 65 years old (Figure 75.1A).² Although the lifetime risk for HF is equal for men¹⁰ and women,² women hospitalized for ADHF are more likely to present with HFpEF and are typically older than men.¹⁴,¹⁵,¹⁶ Women with HF are less likely to have coronary artery disease (CAD) and are more likely to have hypertension and diabetes.¹⁴,¹⁵,¹⁶ In the absence of CAD, the lifetime risk of HF is 11.4% for men and 15.4% for women, suggesting differences partly attributable to hypertension.¹¹

Disparities for HF among different races have also been observed. The U.S. National Inpatient Sample from 2001 to 2014 observed that White patients comprised the majority of primary HF hospitalizations (˜65%), followed by Black (˜20%), Hispanic (˜10%), Asian (˜2%) patients and other races (˜3%).² In the Multi-Ethnic Study of Atherosclerosis (MESA), incident HF was highest in Black Americans, followed by Hispanic, White, and Chinese Americans (4.6, 3.5, 2.4, and 1.0 per 1000 person-years, respectively) (Figure 75.1B).¹⁷ Black Americans have a higher rate of hospitalization and HF death, at least partially attributed to increased comorbid conditions and lower socioeconomic status.¹⁷,¹⁸ Payer status and
socioeconomic status are strongly associated with clinical outcomes in ADHF.¹⁹ HF patients without insurance are typically younger with fewer comorbidities; however, the absence of insurance is associated with longer hospitalization for ADHF, lower rate of implantable cardioverter defibrillator (ICD) implantation, lower rate of beta-blockade, decreased quality of care, and a trend toward increased in-hospital mortality compared with private payer status.¹⁹ Medicaid insurance is associated with increased risk of rehospitalization or death and repeated hospitalization compared with private payer status.²⁰ Decreased quality of care and modest increases in adjusted length of stay for HF have also been observed for Medicare groups compared with private payer status.¹⁹ Limited data also suggest that HF may disproportionately affect lower socioeconomic classes. Approximately one-third of the admissions have been reported to occur among patients within the lowest quartile of household income.² Lower socioeconomic status has been associated with increased mortality and higher risk of readmission for ADHF.²⁰,²¹,²²

Finally, patients admitted for ADHF are increasingly complex with comorbidies including CAD (50%-60%), chronic obstructive pulmonary disease (20%-30%), chronic renal disease (20%-30%), atrial arrhythmias (30%-35%), and other medical problems.²,⁶,¹⁵ Frailty is increasingly identified as a comorbidity (18%-54% in the elderly)²³ and has been associated with a higher rate of hospitalization for ADHF, worse prognosis, and higher mortality compared with nonfrail elderly patients with HF.²³