Abstract
The prevalence of atrial fibrillation (AF) is increasing in the United States as the population ages, but national surveillance is lacking. This cross-sectional study (2006–2014) analyzed data from the Healthcare Cost and Utilization Project’s Nationwide ED Sample, the Nationwide/National Inpatient Sample, and the National Vital Statistics System. Event totals were estimated independently for ED visits, hospitalizations, and mortality, and then collectively after applying criteria to identify mutually exclusive events. Rates were calculated for AF as primary diagnosis/underlying cause of death (primary AF) as well as secondary diagnosis/contributing cause of death (comorbid AF), and standardized by age to the 2010 US population. From 2006–2014, event rates increased for primary AF (249 to 268 per 100,000) and comorbid AF (1,473 to 1,835 per 100,000). In 2014, an estimated 599,790 ED visits, 453,060 hospitalizations, and 21,712 deaths listed AF as primary. A total of 684,470 mutually exclusive primary AF and 4,695,997 mutually exclusive comorbid AF events occurred. Among ED visits and hospitalizations with primary AF, the most common secondary diagnoses were hypertension, heart failure, ischemic heart disease, and diabetes. The mean cost per hospitalization with primary AF was $8,819. Mean costs were higher for those with comorbid AF vs. those without among hospitalizations with a primary diagnosis of ischemic heart disease, heart failure, stroke, hypertension, or diabetes (all p≤0.01). In conclusion, with substantial health and economic impact of AF and an aging US population, improved diagnosis, prevention, management, and surveillance of AF is increasingly important.
Keywords: atrial fibrillation, hospitalization, mortality
Introduction
Patients with atrial fibrillation and flutter (AF) have increased risk of stroke and myocardial infarction,1 cardiovascular hospitalization,2 and mortality.2–5 Despite increasing prevalence6,7 and substantial health and economic impact,1–5,7–10 there is no national surveillance system to track the magnitude of AF-related healthcare and mortality burden across all ages and health insurance provider types.11 This study aimed to overcome surveillance gaps by using national Healthcare Cost and Utilization Project (HCUP) and National Vital Statistics System data from 2006–2014 to describe the burden of AF-related emergency department (ED) visits, inpatient hospitalizations and costs, and mortality. In addition, we examined the burden of comorbid condition events in which AF is listed as a secondary cause and might play a contributing role.
Methods
This cross-sectional study analyzed encounter-level data from 2006–2014 from the HCUP Nationwide Emergency Department Sample (NEDS) and the National (Nationwide) Inpatient Sample (NIS) to examine ED and hospitalization burden, respectively. The NEDS is the largest all-payer ED database in the US, with data from approximately 30 million discharges yearly that are weighted to produce national ED event estimates.12 Data, from approximately 950 hospitals in 30 states, approximate a 20% stratified sample of US hospital-based EDs. The NIS is the largest all-payer inpatient healthcare database in the US that is publicly available, containing data from over 7 million hospitalizations yearly that are weighted to produce national hospitalization event estimates. The NIS approximates a 20% stratified sample of discharges from community hospitals in the US.13 Because the NIS was re-designed in 2012, we used trend weights developed by the Agency for Healthcare Research and Quality (AHRQ) to make estimates comparable for data prior to 2012. National Vital Statistics System (NVSS) data from 2006–2014 were used to examine death events. The NVSS collects information reported on all death certificates filed in every US state and the District of Columbia.14 All events for adults aged ≥18 years were included.
Atrial fibrillation and atrial flutter were examined jointly (referred to as AF throughout) using International Classification of Disease (ICD)-9 Clinical Modification code 427.3x (NEDS and NIS) and ICD-10 code I48 (NVSS). Events were analyzed for AF as primary diagnosis/underlying cause of death (primary AF) and for AF as a secondary diagnosis/contributing cause of death (comorbid AF). Comorbid conditions of interest were selected based on associations with AF in the literature, and included chronic kidney disease (CKD); diabetes; dementia or Alzheimer’s (grouped together as “dementia”); heart failure, valvular heart disease, or cardiomyopathy (grouped together as “HF”); hypertension; ischemic heart disease (IHD); and stroke (including ischemic and hemorrhagic).1 The AHRQ Clinical Classification Software codes were adapted to identify ICD-9 CM and ICD-10 codes for these conditions (Supplemental Table 1).
Event totals were estimated independently for ED visits, hospitalizations, and deaths, and then collectively after applying criteria to identify mutually exclusive events. To estimate mutually exclusive events, we excluded ED visits that resulted in hospitalization, transfer to another hospital, or death, and we excluded hospitalizations that resulted in transfers to another hospital or death.15 Events were then summed across datasets. Event rates were calculated using intercensal population estimates as the denominators,16,17 and were standardized by age to the 2010 US population. Hospitalization costs for inpatient stays were estimated from total charges by applying hospital-level cost-to-charge ratio data from HCUP. Cost-to-charge ratios were not available in NEDS, so costs could not be estimated from ED visit charges. For statistical comparisons, t-tests were used for continuous variables and chi-square tests for categorical variables, and tests were 2-sided. Analyses were conducted using SAS 9.3-callable SUDDAN (Research Triangle Institute, Research Triangle Park, NC) to account for multistage, disproportionate stratified sampling design in the NEDS and NIS. All data were de-identified and publicly available, therefore this study was exempt from Institutional Review Board approval.
Results
In 2014, approximately 600,000 (0.5% of all) ED visits, 450,000 (1.5% of all) hospitalizations, and 22,000 (0.8% of all) deaths listed AF as the primary cause (Table 1). About two thirds of ED visits and hospitalizations with primary AF occurred among Medicare beneficiaries. Among ED visits and hospitalizations with primary AF, the most common secondary diagnoses were hypertension, HF, IHD, and diabetes. As expected, these cardiometabolic conditions occurred more often in ED visits and hospitalizations with AF compared to without AF (all p<0.001). Among deaths with AF as the underlying cause, the most common contributing causes were HF and stroke.
Table 1.
Characteristics of patients age ≥18 years with atrial fibrillation or flutter as the primary diagnoses – Nationwide Emergency Department Sample 2014, National Inpatient Sample 2014 and National Vital Statistics System 2014
| Variable | Emergency Department Visits | Hospitalizations | Deaths | |||
|---|---|---|---|---|---|---|
| Weighted % (Standard error) | Weighted % (Standard error) | % | ||||
| AF+ N=599,790 |
No AF N=110,926,597 |
AF++ N= 453,060 |
No AF N= 29,294,409 |
AF N=21,712 |
No AF N=2,567,995 |
|
| Mean age (years) | 69.3 (0.1) | 47.4 (0.2)£ | 70.2 (0.1) | 57.1 (0.1)£ | 84.7 (0.07) | 74.1 (0.01)£ |
| Age category | ||||||
| 18–44 years | 5.6 (0.1) | 48.9 (0.3)£ | 4.2 (0.1) | 29.7 (0.2)£ | 0.2 | 5.6£ |
| 45–64 years | 28.5 (0.3) | 29.1 (0.3) | 27.6 (0.2) | 29.3 (0.1)£ | 4.3 | 20.4£ |
| 65–74 years | 25.7 (0.2) | 9.7 (0.1)£ | 26.5 (0.2) | 17.2 (0.1)£ | 9.5 | 18.3£ |
| 75–84 years | 24.7 (0.2) | 7.5 (0.1)£ | 26.0 (0.2) | 14.4 (0.1)£ | 26.6 | 24.1£ |
| 85+ years | 15.4 (0.2) | 4.9 (0.1)£ | 15.8 (0.2) | 9.4 (0.1)£ | 59.4 | 31.7£ |
| Sex | ||||||
| Men | 50.1 (0.2) | 42.7 (0.2)£ | 50.0 (0.2) | 41.0 (0.1)£ | 38.1 | 50.6£ |
| Women | 49.9 (0.2) | 57.3 (0.2)£ | 50.0 (0.2) | 59.0 (0.1)£ | 61.9 | 49.4£ |
| Sex and age group | ||||||
| Men and age <65 years | 23.0 (0.3) | 33.4 (0.2)£ | 21.4 (0.2) | 22.6 (0.1)£ | 3.0 | 16.1£ |
| Men and age ≥65 years | 27.2 (0.2) | 9.3 (0.1)£ | 28.7 (0.2) | 18.4 (0.1)£ | 35.2 | 34.5§ |
| Women and age <65 years | 11.2 (0.2) | 44.5 (0.3)£ | 10.4 (0.1) | 36.4 (0.2)£ | 1.6 | 9.9£ |
| Women and age ≥65 years | 38.7 (0.3) | 12.7 (0.2)£ | 39.6 (0.2) | 22.6 (0.1)£ | 60.3 | 39.5£ |
| Health insurance | ||||||
| Medicare | 64.0 (0.5) | 27.6 (0.3)£ | 67.1 (0.3) | 46.0 (0.2)£ | NA | NA |
| Medicaid | 6.4 (0.3) | 25.0 (0.5)£ | 5.9 (0.1) | 18.0 (0.2)£ | NA | NA |
| Private | 23.9 (0.5) | 27.0 (0.5)£ | 22.2 (0.2) | 28.2 (0.3)£ | NA | NA |
| Other | 5.6 (0.2) | 20.1 (0.5)£ | 4.7 (0.1) | 7.6 (0.1)£ | NA | NA |
| Census region (2014 population size, millions) | ||||||
| Northeast (44.2) | 17.7 (1.1) | 18.5 (1.1) | 20.9 (0.5) | 19.1 (0.4)£ | 19.7 | 18.1£ |
| Midwest (52.0) | 25.3 (1.3) | 23.1 (0.9)§ | 24.4 (0.5) | 22.6 (0.4)£ | 24.0 | 23.2§ |
| South (91.7) | 38.2 (1.5) | 40.5 (1.3)§ | 39.8 (0.7) | 39.1 (0.4) | 34.2 | 39.0£ |
| West (56.9) | 18.8 (0.9) | 17.9 (0.7) | 14.9 (0.4) | 19.2 (0.3)£ | 22.1 | 19.6£ |
| Hospital location | ||||||
| Rural | 15.4 (0.7) | 15.7 (0.6) | 11.3 (0.4) | 9.8 (0.2)£ | NA | NA |
| Urban non-teaching | 31.3 (1.3) | 30.3 (1.1) | 29.1 (0.5) | 27.0 (0.3)§ | NA | NA |
| Urban teaching | 53.3 (1.4) | 54.0 (1.2) | 59.6 (0.6) | 63.2 (0.4)£ | NA | NA |
| Comorbidities based the secondary diagnoses codes | ||||||
| Chronic kidney disease | 11.8 (0.2) | 4.1 (0.1)£ | 17.0 (0.2) | 14.5 (0.1)£ | 4.8 | 3.3£ |
| Dementia | 5.4 (0.1) | 2.3 (0.05)£ | 6.9 (0.1) | 6.9 (0.1) | 12.2 | 14.8£ |
| Diabetes mellitus | 24.2 (0.3) | 12.5 (0.2)£ | 29.9 (0.2) | 25.9 (0.1)£ | 9.1 | 9.5§ |
| Heart Failure, valvular heart disease, or cardiomyopathy | 34.2 (0.4) | 5.4 (0.1)£ | 47.9 (0.2) | 17.7 (0.1)£ | 43.6 | 14.4£ |
| Hypertension | 63.5 (0.4) | 25.6 (0.3)£ | 74.7 (0.2) | 50.8 (0.2)£ | 17.9 | 15.8£ |
| Ischemic heart disease | 26.9 (0.3) | 7.1 (0.1)£ | 35.6 (0.2) | 20.7 (0.1)£ | 0.2 | 20.1£ |
| Stroke | 1.4 (0.05) | 0.4 (0.01)£ | 2.1 (0.1) | 1.7 (0.02)£ | 30.5 | 7.6£ |
| None of above conditions | 21.3 (0.4) | 67.3 (0.4)£ | 9.5 (0.1) | 37.1 (0.2)£ | 20.3 | 45.1£ |
P<0.001
P<0.05; AF = atrial fibrillation or flutter
10.3% of included AF ED visits were atrial flutter
11.4% of included AF hospitalizations were atrial flutter.
Source of regional population sizes: U.S. Census Bureau, 2014 American Community Survey 1-Year Estimates
Approximately 4 million (3.6% of all) ED visits, 3.5 million (12.0% of all) hospitalizations, and 100,000 (4.5% of all) deaths listed comorbid AF in 2014 (Table 2). Similar age and sex patterns were observed for events with comorbid AF compared to events with primary AF. Over 80% of ED visits and hospitalizations with comorbid AF occurred among Medicare beneficiaries. For ED visits and hospitalizations with AF as a secondary diagnosis, the most common primary diagnoses were HF, IHD, and stroke, among our conditions of interest. These primary diagnoses were more common among ED visits and hospitalizations with AF as a secondary diagnosis than without (all p<0.001). Among deaths with AF as a contributing cause, the most common underlying cause was IHD (21.9%).
Table 2.
Characteristics of patients age ≥18 years with atrial fibrillation or flutter as the secondary diagnoses – Nationwide Emergency Department Sample 2014, National Inpatient Sample 2014 and National Vital Statistics System 2014*
| Demographic | Emergency Department Visits | Hospitalizations | Deaths | |||
|---|---|---|---|---|---|---|
| Weighted % (Standard error) | Weighted % (Standard error) | % | ||||
| AF N=3,952,915 |
No AF N=106,973,681 |
AF N= 3,523,726 |
No AF N= 25,770,682 |
AF N=115,719 |
No AF N=2,452,276 |
|
| Mean age (years) | 75.6 (0.1) | 46.4 (0.1)£ | 75.7 (0.1) | 54.5 (0.1)£ | 82.9 (0.03) | 73.6 (0.01)£ |
| Age category | ||||||
| 18–44 years | 2.1 (0.1) | 50.6 (0.3)£ | 1.4 (0.03) | 33.6 (0.2)£ | 0.2 | 5.8£ |
| 45–64 years | 15.7 (0.3) | 29.6 (0.2)£ | 15.4 (0.1) | 31.2 (0.1)£ | 5.6 | 21.1£ |
| 65–74 years | 21.4 (0.2) | 9.2 (0.1)£ | 23.5 (0.1) | 16.3 (0.1)£ | 13.0 | 18.5£ |
| 75–84 years | 32.0 (0.2) | 6.6 (0.1)£ | 32.8 (0.1) | 11.9 (0.1)£ | 29.7 | 23.8£ |
| 85+ years | 28.7 (0.3) | 4.0 (0.1)£ | 26.9 (0.2) | 7.0 (0.1)£ | 51.4 | 30.7£ |
| Sex | ||||||
| Men | 50.1 (0.2) | 42.4 (0.2)£ | 52.0 (0.1) | 39.5 (0.1)£ | 46.9 | 50.7£ |
| Women | 49.9 (0.2) | 57.6 (0.2)£ | 48.0 (0.1) | 60.5 (0.1)£ | 53.1 | 49.3£ |
| Sex and age group | ||||||
| Men and age <65 years | 11.3 (0.2) | 34.2 (0.2)£ | 10.9 (0.1) | 24.2 (0.1)£ | 4.0 | 16.6£ |
| Men and age ≥65 years | 38.8 (0.2) | 8.2 (0.1)£ | 41.1 (0.1) | 15.3 (0.1)£ | 42.9 | 34.1£ |
| Women and age <65 years | 6.6 (0.1) | 45.9 (0.2)£ | 5.9 (0.1) | 40.5 (0.2)£ | 1.9 | 10.3£ |
| Women and age ≥65 years | 43.3 (0.2) | 11.6 (0.2)£ | 42.1 (0.1) | 20.0 (0.1)£ | 51.2 | 39.0£ |
| Health insurance | ||||||
| Medicare | 80.9 (0.5) | 25.7 (0.3)£ | 81.8 (0.2) | 41.1 (0.2)£ | NA | NA |
| Medicaid | 5.1 (0.2) | 25.8 (0.5)£ | 4.2 (0.1) | 19.9 (0.2)£ | NA | NA |
| Private | 10.8 (0.4) | 27.6 (0.5)£ | 11.3 (0.2) | 30.5 (0.3)£ | NA | NA |
| Other | 3.1 (0.1) | 20.7 (0.5)£ | 2.6 (0.1) | 8.3 (0.1)£ | NA | NA |
| Census region (2014 population size, millions) | ||||||
| Northeast (44.2) | 18.2 (1.2) | 18.5 (1.1) | 20.6 (0.5) | 18.9 (0.4)£ | 19.0 | 18.1£ |
| Midwest (52.0) | 24.5 (1.4) | 23.1 (1.0) | 24.5 (0.5) | 22.3 (0.4)£ | 23.7 | 23.2£ |
| South (91.7) | 38.3 (1.6) | 40.6 (1.3)§ | 37.3 (0.5) | 39.3 (0.4)£ | 33.6 | 39.3£ |
| West (56.9) | 18.9 (1.0) | 17.9 (0.7) | 17.6 (0.4) | 19.5 (0.3)£ | 23.7 | 19.4£ |
| Hospital location | ||||||
| Rural | 13.1 (0.6) | 15.8 (0.6)£ | 10.4 (0.3) | 9.7 (0.2)£ | NA | NA |
| Urban non-teaching | 31.2 (1.4) | 30.3 (1.1) | 28.2 (0.4) | 26.8 (0.3)£ | NA | NA |
| Urban teaching | 55.7 (1.5) | 54.0 (1.1) | 61.4 (0.5) | 63.5 (0.4)£ | NA | NA |
| Primary diagnosis | ||||||
| Chronic kidney disease | 0.1 (0.01) | 0.1 (0.01) | 0.1 (0.01) | 0.1 (0.01) | 1.0 | 1.1§ |
| Dementia | 0.5 (0.02) | 0.2 (0.004) £ | 0.5 (0.01) | 0.4 (0.01)£ | 9.3 | 9.6£ |
| Diabetes mellitus | 1.0 (0.02) | 1.0 (0.01) | 1.1 (0.01) | 1.9 (0.02)£ | 3.9 | 2.9£ |
| Heart Failure, valvular heart disease, or cardiomyopathy | 9.4 (0.1) | 0.6 (0.01) £ | 12.9 (0.1) | 2.3 (0.02)£ | 9.3 | 5.1£ |
| Hypertension | 1.5 (0.03) | 1.0 (0.01) £ | 1.5 (0.03) | 1.0 (0.01)£ | 5.9 | 2.7£ |
| Ischemic heart disease | 3.4 (0.1) | 0.8 (0.02) £ | 5.3 (0.1) | 3.2 (0.04)£ | 21.9 | 13.4£ |
| Stroke | 3.4 (0.1) | 0.5 (0.01) £ | 4.3 (0.05) | 2.1 (0.02)£ | 8.2 | 4.5£ |
| None of above conditions | 80.7 (0.2) | 95.8 (0.04) £ | 74.4 (0.1) | 89.1 (0.1)£ | 42.8 | 61.2£ |
P<0.001
P<0.05; AF = atrial fibrillation or flutter
Source of regional population sizes: U.S. Census Bureau, 2014 American Community Survey 1-Year Estimates
Patients with AF as the primary diagnoses were excluded from this table.
Nearly 700,000 mutually exclusive events occurred with AF as the primary cause in 2014 (268 per 100,000), while nearly 4.7 million mutually exclusive comorbid AF events occurred (1,835 per 100,000) (Table 3). From 2006 to 2014, the primary AF event rate increased 8% from 249 to 268 per 100,000, while the comorbid AF event rate increased 25% from 1,473 to 1,835 per 100,000, respectively, after age-standardization to the 2010 US population (Figure 1, and detailed results available in Supplemental Tables 2 and 3). Crude rates of primary AF tended to be highest in the oldest women, whereas crude rates of comorbid AF were highest in the oldest men.
Table 3.
The mutually exclusive event burden of atrial fibrillation or flutter, Nationwide Emergency Department Sample 2014, National Inpatient Sample 2014 and National Vital Statistics System 2014
| Total AF, Primary Diagnosis | Total AF, Secondary Diagnosis | |||||
|---|---|---|---|---|---|---|
| N | % | Rate/100,000 people | N | % | Rate/100,000 people | |
| Total* | 684,470 | 268.2 | 4,695,997 | 1835.4 | ||
| Emergency department | 224,448 | 32.8 | 88.1 | 1,346,436 | 28.7 | 527.9 |
| Hospitalization | 483,310 | 64.0 | 171.6 | 3,233,841 | 68.9 | 1262.0 |
| Deaths | 21,712 | 3.2 | 8.6 | 115,719 | 2.5 | 45.5 |
| Age category | ||||||
| 18–44 years | 35,698 | 5.2 | 30.9 | 95,349 | 2.0 | 82.6 |
| 45–64 years | 191,823 | 28.0 | 229.6 | 756,232 | 16.1 | 905.3 |
| 65–74 years | 178,709 | 26.1 | 677.0 | 1,067,627 | 22.7 | 4044.3 |
| 75–84 years | 170,405 | 24.9 | 1245.4 | 1,507,461 | 32.1 | 11017.3 |
| 85+ years | 107,836 | 15.8 | 1750.0 | 1,269,327 | 27.0 | 20598.5 |
| Sex* | ||||||
| Men | 344,029 | 50.3 | 296.4 | 2,391,525 | 50.9 | 2143.6 |
| Women | 340,441 | 49.7 | 237.7 | 2,304,472 | 49.1 | 1581.2 |
| Sex and age group | ||||||
| Men and age <65 years | 152,450 | 22.3 | 154.0 | 539,051 | 11.5 | 544.5 |
| Men and age ≥65 years | 191,579 | 28.0 | 941.4 | 1,852,474 | 39.4 | 9102.5 |
| Women and age <65 years | 75,070 | 11.0 | 75.0 | 312,530 | 6.7 | 312.4 |
| Women and age ≥65 years | 265,371 | 38.8 | 1024.9 | 1,991,942 | 42.4 | 7693.3 |
Rates are standardized by age to the 2010 U.S. Census Population distribution among adults aged ≥18 years; AF = atrial fibrillation or flutter; ED = emergency department.
The crude age-sex specific rates were reported for sub group estimates.
Figure 1: Trends in overall mutually exclusive atrial fibrillation or flutter events, by age group and primary versus secondary cause – Nationwide Emergency Department Sample, National (Nationwide) Inpatient Sample and National Vital Statistics System, 2006–2014.
Rate totals standardized by age to the 2010 U.S. Census Population distribution among adults aged ≥18 years. Crude age-sex specific rates were reported for subgroup estimates. Includes combination of emergency department encounters, hospitalizations, and deaths. AF = atrial fibrillation and flutter. See Supplemental Tables 2 and 3 for detailed numeric results.
Almost two thirds (62.5%) of ED visits with primary AF resulted in admission to the hospital or transfer to another facility (vs 17.9% of ED visits without AF, p<0.001), and the mean total charge of ED visits for primary AF was approximately $4,000 (Table 4). The estimated mean cost per hospitalization with primary AF was approximately $8,800, with a mean length of stay of 3.5 days. Mean costs were significantly higher for those with comorbid AF vs. those without AF among hospitalizations with a primary diagnosis of hypertension (34% greater cost), IHD (32% greater cost), diabetes (29% greater cost), HF (19% greater cost), or stroke (3% greater cost). However, hospitalizations costs with comorbid AF and a primary diagnosis of CKD or dementia were not significantly different from those without AF.
Table 4.
Emergency department and hospitalization outcomes, charges, and costs among patients with or without atrial fibrillation or flutter, by primary diagnosis, Nationwide Emergency Department Sample 2014 and National Inpatient Sample 2014
| Primary Diagnosis | Emergency Department Visits | Hospitalizations | ||||
|---|---|---|---|---|---|---|
| Weighted Mean or Percent (Standard Error) | P-value | Weighted Mean or Percent (Standard Error) | P-value | |||
| Primary AF | No AF++ | Primary AF | No AF++ | |||
| Total | ||||||
| Admitted to hospital or transferred | 62.5% (0.7) | 17.9% (0.2) | <0.0001 | 2.3% (0.1) | 2.0% (0.02) | <0.0001 |
| Died | 0.04% (0.01) | 0.2% (0.004) | <0.0001 | 0.9% (0.03) | 2.2% (0.02) | <0.0001 |
| Average length of stay (days) | NA | NA | 3.5 (0.02) | 4.8 (0.02) | <0.0001 | |
| Total charge | $4,040 (98) | $3,300 (77) | <0.0001 | $34,734 (490) | $45,164 (547) | <0.0001 |
| Total cost | NA | NA | $8,819 (83) | $11,711 (97) | <0.0001 | |
| ED Visits | Hospitalizations | |||||
| Comorbid AF* | No AF | Comorbid AF* | No AF | |||
| Chronic kidney disease (CKD) | ||||||
| Admitted to hospital or transferred | 44.3 (3.6) | 22.3 (3.2) | <0.0001 | + | 1.0 (0.2) | NA |
| Died | + | 0.22 (0.1) | NA | + | 3.5 (0.5) | NA |
| Average length of stay (days) | NA | NA | 5.6 (0.5) | 4.0 (0.3) | 0.001 | |
| Total charge | $4,400(312) | $4,335 (322) | 0.85 | $48,336 (4067) | $44,954 (4163) | 0.37 |
| Total cost | NA | NA | $12,756 (1017) | $12,332 (1190) | 0.67 | |
| Dementia | ||||||
| Admitted to hospital or transferred | 66.4 (1.4) | 33.8 (1.0) | <0.0001 | 5.2 (0.4) | 4.5 (0.2) | 0.12 |
| Died | + | + | NA | 2.5 (0.3) | 1.7 (0.1) | 0.01 |
| Average length of stay (days) | NA | NA | 9.3 (0.3) | 10.2 (0.2) | 0.0004 | |
| Total charge | $3,743 (147) | $3,724 (101) | 0.87 | $32,878 (924) | $32,595 (724) | 0.71 |
| Total cost | NA | NA | $9,564 (298) | $9,430 (189) | 0.63 | |
| Diabetes | ||||||
| Admitted to hospital or transferred | 69.3 (0.9) | 39.2 (0.6) | <0.0001 | 2.0 (0.2) | 1.3 (0.04) | <0.0001 |
| Died | + | 0.03 (0.002) | NA | 1.9 (0.2) | 0.5 (0.02) | <0.0001 |
| Average length of stay (days) | NA | NA | 6.4 (0.1) | 4.6 (0.03) | <0.0001 | |
| Total charge | $3,243 (97) | $3,151 (83) | 0.18 | $54,640 (1189) | $37,901 (480) | <0.0001 |
| Total cost | NA | NA | $13,685 (221) | $9,661 (86) | <0.0001 | |
| Heart Failure, Valvular Heart Disease, or Cardiomyopathy | ||||||
| Admitted to hospital or transferred | 88.9 (0.4) | 76.5 (0.5) | <0.0001 | 2.7 (0.1) | 3.3 (0.1) | <0.0001 |
| Died | 0.05 (0.01) | 0.15 (0.01) | <0.0001 | 3.5 (0.1) | 2.5 (0.1) | <0.0001 |
| Average length of stay (days) | NA | NA | 6.1 (0.1) | 5.1 (0.04) | <0.0001 | |
| Total charge | $2,864 (81) | $3,413 (96) | <0.0001 | $66,158 (1486) | $55,624 (1154) | <0.0001 |
| Total cost | NA | NA | $16,948 (323) | $14,213 (232) | <0.0001 | |
| Hypertension | ||||||
| Admitted to hospital or transferred | 62.8 (1.1) | 21.2 (0.5) | <0.0001 | 2.2 (0.2) | 1.4 (0.1) | <0.0001 |
| Died | + | 0.03 (0.01) | NA | 3.6 (0.2) | 0.9 (0.05) | <0.0001 |
| Average length of stay (days) | NA | NA | 6.3 (0.1) | 4.2 (0.04) | <0.0001 | |
| Total charge | $3,416 (101) | $3,360 (87) | 0.40 | $56,213 (1645) | $41,981 (860) | <0.0001 |
| Total cost | NA | NA | $13,991 (394) | $10,468 (196) | <0.0001 | |
| Ischemic heart disease | ||||||
| Admitted to hospital or transferred | 90.6 (0.3) | 81.7 (0.5) | <0.0001 | 5.7 (0.2) | 7.4 (0.2) | <0.0001 |
| Died | 0.3 (0.03) | 0.6 (0.03) | <0.0001 | 5.4 (0.1) | 2.8 (0.04) | <0.0001 |
| Average length of stay (days) | NA | NA | 6.4 (0.1) | 4.0 (0.02) | <0.0001 | |
| Total charge | $4,447 (157) | $6,882 (233) | <0.0001 | $104,357 (1609) | $78,039 (942) | <0.0001 |
| Total cost | NA | NA | $25,877 (281) | $19,282 (146) | <0.0001 | |
| Stroke | ||||||
| Admitted to hospital or transferred | 95.1 (0.3) | 88.9 (0.4) | <0.0001 | 2.6 (0.1) | 2.9 (0.1) | 0.03 |
| Died | 0.4 (0.04) | 0.4 (0.02) | 0.77 | 9.9 (0.2) | 5.8 (0.1) | <0.0001 |
| Average length of stay (days) | NA | NA | 5.7 (0.1) | 4.9 (0.1) | <0.0001 | |
| Total charge | $3,269 (106) | $4,360 (113) | <0.0001 | $59,269 (1040) | $58,712 (1141) | 0.39 |
| Total cost | NA | NA | $14,923 (202) | $14,554 (212) | 0.01 | |
Not reportable based on the estimates with a relative standard error greater than 0.30. AF = atrial fibrillation or flutter
These columns include all events with primary diagnosis other than AF for rows pertaining to “Total” events.
Results for patients with or without AF as a secondary diagnosis, “comorbid AF”, exclude patients with AF as a principal diagnosis.
Discussion
The healthcare and mortality burden of AF in the United States is substantial, and prevalence is increasing.18,19 In 2014, almost 700,000 mutually exclusive primary AF events (ED visits, hospitalizations, and deaths) and nearly 4.7 million comorbid AF events occurred, and event rates increased during 2006–2014. Among hospitalizations with primary AF, cardiovascular secondary diagnoses were common, especially hypertension (over 2 of every 3), HF (nearly 1 of every 2), IHD (around 1 of every 3), and diabetes (around 1 of every 4). Hospitalization costs were higher for those with comorbid AF vs. those without AF for patients with a primary diagnosis of IHD, HF, stroke, hypertension, or diabetes.
Our estimates of increasing AF burden in the US are consistent with other research. Two Medicare studies, from 1992–2002 and 1993–2007, observed stable incidence rates for AF but increasing prevalence among persons aged ≥65.18,19 Using NIS data, Patel et al. found that the AF hospitalization rate increased by 14.4% from 2000–2010,20 while Freeman et al. observed a more modest increase among Medicare beneficiaries.21 Given the strong association between AF incidence and age, it is expected that an aging population would contribute to increases in AF events.1,22 However, we also observed increases in AF event rates after age-standardization to the 2010 US population, and age-standardized increases in prevalence have been reported.22,23 Increases in AF might also be due to increased awareness and diagnosis,24 including technological advances in detection devices and the ability to detect AF by interrogating pacemakers.25
Risk factors for AF may also be contributing to changes in AF burden.1,22 Some, such as hypertension, diabetes, and smoking, may be antecedents of AF, while others, such as HF, stroke, myocardial infarction, and valvular disease, may be both risk factors for AF and clinical sequelae of AF.22,26 Although prevalence of certain risk factors, such as smoking, are improving in the population, others have worsened.24 For example, higher body mass index increases AF risk,22,27 indicating that increases in obesity prevalence in recent decades may have contributed to increased AF burden.24
The substantial burden of AF has important cost implications. In 2001, 44% of direct costs of AF were attributable to primary AF hospitalizations.28 We estimated the mean cost per hospitalization with AF as primary diagnosis at $8,819 in 2014, which was similar to the 2010 cost.20 Although length of hospitalization did not increase, mean hospitalization cost increased by 24% between 2000–2010, after adjusting for inflation.20 Increasing hospitalization costs may be due to increased costs of clinical services overall,29 the shifting of less costly AF care to an outpatient setting, or use of more sophisticated services, such as ablation therapy.30 Of note, increased costs for AF have occurred simultaneously with decreases in inpatient mortality and AF readmission.21
In addition to the costs of primary AF, events in which AF might play a contributing role also have substantial costs, and were estimated to account for 29% of US spending on AF treatment.22 We observed a larger increase in comorbid AF event rate (25%) than primary AF event rate (8%) between 2006–2014, and costs were generally higher for comorbid than primary AF hospitalizations. Consistent with prior work,31 we observed greater costs for events with comorbid AF compared to without. AF may exacerbate other cardiovascular conditions and increase severity of CVD events, leading to greater costs. For example, strokes with AF are often more severe, with longer hospitalizations, greater disability, and greater likelihood of mortality.32,33
This study was strengthened by the use of large, all-payer datasets, weighted to represent the US population. However, there were limitations. First, burden estimates did not capture treatment of AF in outpatient settings. Second, NEDS and NIS capture event-level data, not patient-level data, so patient factors (such as yearly per-patient costs and readmission rates) could not be explored. Third, this study does not describe costs of AF, but rather the cost of hospitalizations among those with AF. Fourth, burden estimates were dependent on accurate coding of AF and comorbidities, and biases may have resulted from changes in coding patterns over time, or underreporting of AF (particularly asymptomatic AF). Also, US death records are subject to misclassification, and, for example, deaths classified as primary AF may have had other underlying causes. Fifth, AF is a heterogeneous condition, and this study was not able to distinguish between sub-types of AF, from transient episodes to permanent arrhythmia.
This study of ED visits, hospitalizations, and mortality showed a substantial and increasing burden of AF. The US prevalence of AF is projected to rise from an estimated 5.2 million in 2010 to 12.1 million in 2030.6 The majority of the burden of care for AF patients will impact Medicare, as approximately two thirds of ED visits and hospitalizations with primary AF, and over 80% of ED visits and hospitalizations with comorbid AF, occurred among Medicare beneficiaries. As the population ages and health care costs continue to rise, improved AF diagnosis, prevention, and management, as well as surveillance of burden, will be increasingly important.
Supplementary Material
Acknowledgements
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. The authors report no conflicts of interest or financial disclosures.
No external funding was received for this work.
References
- 1.Lip GY, Fauchier L, Freedman SB, Van Gelder I, Natale A, Gianni C, Nattel S, Potpara T, Rienstra M, Tse HF, Lane DA. Atrial fibrillation. Nat Rev Dis Primers 2016;2:doi: 10.1038/nrdp.2016.1016. [DOI] [PubMed] [Google Scholar]
- 2.Panaccio MP, Cummins G, Wentworth C, Lanes S, Reynolds SL, Reynolds MW, Miao R, Koren A. A common data model to assess cardiovascular hospitalization and mortality in atrial fibrillation patients using administrative claims and medical records. Clin Epidemiol 2015;7:77–90. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Benjamin EJ, Wolf PA, D’Agostino RB, Silbershatz H, Kannel WB, Levy D. Impact of Atrial Fibrillation on the Risk of Death: The Framingham Heart Study. Circulation 1998;98:946–952. [DOI] [PubMed] [Google Scholar]
- 4.Chamberlain AM, Gersh BJ, Alonso A, Chen LY, Berardi C, Manemann SM, Killian JM, Weston SA, Roger VL. Decade-long trends in atrial fibrillation incidence and survival: a community study. Am J Med 2015;128:260–267. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Gorelick PB, Scuteri A, Black SE, Decarli C, Greenberg SM, Iadecola C, Launer LJ, Laurent S, Lopez OL, Nyenhuis D, Petersen RC, Schneider JA, Tzourio C, Arnett DK, Bennett DA, Chui HC, Higashida RT, Lindquist R, Nilsson PM, Roman GC, Sellke FW, Seshadri S. Vascular contributions to cognitive impairment and dementia: a statement for healthcare professionals from the american heart association/american stroke association. Stroke 2011;42:2672–2713. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Colilla S, Crow A, Petkun W, Singer DE, Simon T, Liu X. Estimates of current and future incidence and prevalence of atrial fibrillation in the U.S. adult population. Am J Cardiol 2013;112:1142–1147. [DOI] [PubMed] [Google Scholar]
- 7.Naccarelli GV, Varker H, Lin J, Schulman KL. Increasing prevalence of atrial fibrillation and flutter in the United States. Am J Cardiol 2009;104:1534–1539. [DOI] [PubMed] [Google Scholar]
- 8.Kim MH, Johnston SS, Chu B-C, Dalal MR, Schulman KL. Estimation of Total Incremental Health Care Costs in Patients With Atrial Fibrillation in the United States. Circ Cardiovasc Qual Outcomes 2011;4:313–320. [DOI] [PubMed] [Google Scholar]
- 9.Go AS, Hylek EM, Phillips KA, Chang Y, Henault LE, Selby JV, Singer DE. Prevalence of diagnosed atrial fibrillation in adults: National implications for rhythm management and stroke prevention: the anticoagulation and risk factors in atrial fibrillation (atria) study. JAMA 2001;285:2370–2375. [DOI] [PubMed] [Google Scholar]
- 10.Miyasaka Y, Barnes ME, Gersh BJ, Cha SS, Bailey KR, Abhayaratna WP, Seward JB, Tsang TSM. Secular Trends in Incidence of Atrial Fibrillation in Olmsted County, Minnesota, 1980 to 2000, and Implications on the Projections for Future Prevalence. Circulation 2006;114:119–125. [DOI] [PubMed] [Google Scholar]
- 11.Goff DC, Brass L, Braun LT, Croft JB, Flesch JD, Fowkes FGR, Hong Y, Howard V, Huston S, Jencks SF, Luepker R, Manolio T, O’Donnell C, Marie Robertson R, Rosamond W, Rumsfeld J, Sidney S, Zheng ZJ. Essential Features of a Surveillance System to Support the Prevention and Management of Heart Disease and Stroke. A Scientific Statement From the American Heart Association Councils on Epidemiology and Prevention, Stroke, and Cardiovascular Nursing and the Interdisciplinary Working Groups on Quality of Care and Outcomes Research and Atherosclerotic Peripheral Vascular Disease 2007;115:127–155. [DOI] [PubMed] [Google Scholar]
- 12.Healthcare Cost and Utilization Project (HCUP). NEDS Overview Accessed on December 8, 2016 www.hcup-us.ahrq.gov/nedsoverview.jsp
- 13.Healthcare Cost and Utilization Project (HCUP). NIS Overview Accessed on December 8, 2016 www.hcup-us.ahrq.gov/nisoverview.jsp
- 14.Centers for Disease Control and Prevention. National Vital Statistics System Accessed on Feb 13, 2017 https://www.cdc.gov/nchs/nvss/about_nvss.htm
- 15.Ritchey MD, Loustalot F, Wall HK, Steiner CA, Gillespie C, George MG, Wright JS. Million Hearts - Description of the National Surveillance and Modeling Methodology Used to Monitor the Number of Cardiovascular Events Prevented During 2012–2016. J Am Heart Assoc 2017: 10.1161/JAHA.1117.006021. [DOI] [PMC free article] [PubMed]
- 16.US Census Bureau Population Division. Projected population by single year of age, sex, race, and Hispanic origin for the United States: 2014 to 2060 Accessed on June 14, 2017 https://www.census.gov/population/projections/data/national/2014.html
- 17.US Dept of Health and Human Services National Center for Health Statistics. Bridged-Race Population Estimates, United States July 1st resident population by state, county, age, sex, bridged-race, and Hispanic origin. Compiled from 1990–1999 bridged-race intercensal population estimates (released by NCHS on 7/26/2004); revised bridged-race 2000–2009 intercensal population estimates (released by NCHS on 10/26/2012); and bridged-race Vintage 2015 (2010–2015) postcensal population estimates (released by NCHS on 6/28/2016) Accessed on June 14, 2017 http://wonder.cdc.gov/bridged-race-v2015.html
- 18.Lakshminarayan K, Solid CA, Collins AJ, Anderson DC, Herzog CA. Atrial Fibrillation and Stroke in the General Medicare Population, A 10-Year Perspective (1992 to 2002). Stroke 2006;37:1969–1974. [DOI] [PubMed] [Google Scholar]
- 19.Piccini JP, Hammill BG, Sinner MF, Jensen PN, Hernandez AF, Heckbert SR, Benjamin EJ, Curtis LH. Incidence and Prevalence of Atrial Fibrillation and Associated Mortality Among Medicare Beneficiaries, 1993–2007. Circ Cardiovasc Qual Outcomes 2012;5:85–93. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Patel NJ, Deshmukh A, Pant S, Singh V, Patel N, Arora S, Shah N, Chothani A, Savani GT, Mehta K, Parikh V, Rathod A, Badheka AO, Lafferty J, Kowalski M, Mehta JL, Mitrani RD, Viles-Gonzalez JF, Paydak H. Contemporary Trends of Hospitalization for Atrial Fibrillation in the United States, 2000 Through 2010: Implications for Healthcare Planning. Circulation 2014;129:2371–2379. [DOI] [PubMed] [Google Scholar]
- 21.Freeman JV, Wang Y, Akar JG, Desai N, Krumholz HM. National Trends in Atrial Fibrillation Hospitalization, Readmission,and Mortality for Medicare Beneficiaries, 1999–2013. Circulation 2017. [DOI] [PubMed]
- 22.Ball J, Carrington MJ, McMurray JJ, Stewart S. Atrial fibrillation: profile and burden of an evolving epidemic in the 21st century. Int J Cardiol 2013;167:1807–1824. [DOI] [PubMed] [Google Scholar]
- 23.Stefansdottir H, Aspelund T, Gudnason V, Arnar DO. Trends in the incidence and prevalence of atrial fibrillation in Iceland and future projections. Europace 2011;13:1110–1117. [DOI] [PubMed] [Google Scholar]
- 24.Benjamin EJ, Blaha MJ, Chiuve SE, Cushman M, Das SR, Deo R, de Ferranti SD, Floyd J, Fornage M, Gillespie C, Isasi CR, Jiménez MC, Jordan LC, Judd SE, Lackland D, Lichtman JH, Lisabeth L, Liu S, Longenecker CT, Mackey RH, Matsushita K, Mozaffarian D, Mussolino ME, Nasir K, Neumar RW, Palaniappan L, Pandey DK, Thiagarajan RR, Reeves MJ, Ritchey M, Rodriguez CJ, Roth GA, Rosamond WD, Sasson C, Towfighi A, Tsao CW, Turner MB, Virani SS, Voeks JH, Willey JZ, Wilkins JT, Wu JH, Alger HM, Wong SS, Muntner P. Heart Disease and Stroke Statistics—2017 Update: A Report From the American Heart Association. Circulation 2017:e16–e458. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Meschia JF. Pacemakers as Atrial Fibrillation Detectors: Finding Racial Differences and Opportunities for Preventing Stroke. J Am Heart Assoc 2016;5: 10.1161/JAHA.1115.003090. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Benjamin EJ, Chen P-S, Bild DE, Mascette AM, Albert CM, Alonso A, Calkins H, Connolly SJ, Curtis AB, Darbar D, Ellinor PT, Go AS, Goldschlager NF, Heckbert SR, Jalife J, Kerr CR, Levy D, Lloyd-Jones DM, Massie BM, Nattel S, Olgin JE, Packer DL, Po SS, Tsang TSM, Van Wagoner DR, Waldo AL, Wyse DG. Prevention of Atrial Fibrillation. Report From a National Heart, Lung, and Blood Institute Workshop 2009;119:606–618. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Chatterjee NA, Giulianini F, Geelhoed B, Lunetta KL, Misialek JR, Niemeijer MN, Rienstra M, Rose LM, Smith AV, Arking DE, Ellinor PT, Heeringa J, Lin H, Lubitz SA, Soliman EZ, Verweij N, Alonso A, Benjamin EJ, Gudnason V, Stricker BH, van der Harst P, Chasman DI, Albert CM. Genetic Obesity and the Risk of Atrial Fibrillation-Causal Estimates from Mendelian Randomization. Circulation 2016: 10.1161/CIRCULATIONAHA.1116.024921. [DOI] [PMC free article] [PubMed]
- 28.Coyne KS, Paramore C, Grandy S, Mercader M, Reynolds M, Zimetbaum P. Assessing the direct costs of treating nonvalvular atrial fibrillation in the United States. Value Health 2006;9:348–356. [DOI] [PubMed] [Google Scholar]
- 29.Martin AB, Hartman M, Benson J, Catlin A. National Health Spending In 2014: Faster Growth Driven By Coverage Expansion And Prescription Drug Spending. Health Affairs 2015: 10.1377/hlthaff.2015.1194. [DOI] [PubMed]
- 30.Lee R, Kruse J, McCarthy PM. Surgery for atrial fibrillation. Nat Rev Cardiol 2009;6:505–513. [DOI] [PubMed] [Google Scholar]
- 31.Wolf PA, Mitchell JB, Baker CS, Kannel WB, D’Agostino RB. Impact of atrial fibrillation on mortality, stroke, and medical costs. Arch Intern Med 1998;158:229–234. [DOI] [PubMed] [Google Scholar]
- 32.Lin HJ, Wolf PA, Kelly-Hayes M, Beiser AS, Kase CS, Benjamin EJ, D’Agostino RB. Stroke severity in atrial fibrillation. The Framingham Study. Stroke 1996;27:1760–1764. [DOI] [PubMed] [Google Scholar]
- 33.Jorgensen HS, Nakayama H, Reith J, Raaschou HO, Olsen TS. Acute stroke with atrial fibrillation. The Copenhagen Stroke Study. Stroke 1996;27:1765–1769. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.