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. Author manuscript; available in PMC: 2018 Jan 1.
Published in final edited form as: Am J Med. 2016 Aug 31;130(1):93.e9–93.e28. doi: 10.1016/j.amjmed.2016.07.030

All-Payer Analysis of Heart Failure Hospitalization 30-Day Readmission: Comorbidities Matter

Jonathan D Davis 1, Margaret A Olsen 3,4, Kerry Bommarito 3, Shane J LaRue 2, Mohammed Saeed 3, Michael W Rich 2, Justin M Vader 2
PMCID: PMC5482409  NIHMSID: NIHMS859044  PMID: 27592085

Abstract

BACKGROUND

Thirty-day readmission following heart failure hospitalization impacts hospital performance measures and reimbursement. We investigated readmission characteristics and the magnitude of 30-day hospital readmissions after hospital discharge for heart failure using the Healthcare Cost and Utilization Project State Inpatient Databases (SID).

METHODS

Adults aged ≥ 40 years hospitalized with a primary discharge diagnosis of heart failure from 2007–2011 were identified in the California, New York, and Florida SIDs. Characteristics of patients with and without 7-, 8-30-, and 30-day readmission, and primary readmission diagnoses and risk factors for readmission were examined.

RESULTS

We identified 547,068 patients with mean age 74.7 years; 50.7% were female, 65.4% were white. Of 117,123 patients (21.4%) readmitted within 30 days (median 12 days), 69.7% had a non-heart failure primary readmission diagnosis. Patients with 30-day readmissions more frequently had a history of previous admission with heart failure as a secondary diagnosis, fluid and electrolyte disorders and chronic deficiency anemia. There were no significant clinical differences at baseline between those patients whose first readmission was in the first 7 days after discharge versus in the next 23 days. The most common primary diagnoses for 30-day non-heart failure readmissions were other cardiovascular conditions (14.9%), pulmonary disease (8.5%), and infections (7.7%).

CONCLUSIONS

In this large all-payer cohort, ~70% of 30-day readmissions were for non-heart failure causes, and the median time to readmission was 12 days. Future interventions to reduce readmissions should focus on common comorbid conditions that contribute to readmission burden.

Keywords: Heart Failure, Patient Readmission

INTRODUCTION

Heart failure accounts for over a quarter of all cardiovascular hospitalizations in the United States (US)1, and 30-day readmission following heart failure hospitalization is linked to quality measures and reimbursement2. Most readmissions occur early in this 30-day window, with a reported median time to 30-day readmission of less than 15 days.3 Readmissions after heart failure hospitalization are usually for diagnoses other than heart failure, with reported rates of 70% in Medicare3 and 50% in younger populations.4 These rates are higher than those reported 20–30 years ago.5 A range of strategies to reduce readmission have focused primarily on management of heart failure rather than prevalent comorbid conditions that are now the primary drivers of early re-hospitalization.6–8 Recent data indicate that 30-day readmission rates following heart failure hospitalization have declined modestly9,10 yet remain unacceptably high. As the prevalence of heart failure is projected to increase 46% by 203011, more comprehensive elucidation of modifiable or preventable readmission risk factors and reasons for readmission are necessary.

The Healthcare Cost and Utilization Project (HCUP) State Inpatient Databases (SID) collect hospital billing data for all admissions to acute-care community hospitals from all payers, including Medicare, Medicaid, other nonfederal payers, and patients who are uninsured.12,13 Certain states provide encrypted identifiers to allow tracking of individual patient readmissions and a timing variable that serves as an encrypted version of admission date.14

This study aimed to characterize patterns of readmission within 30 days following heart failure hospitalization, identify the most common reasons for early readmission, and elucidate comorbid conditions associated with increased risk for re-hospitalization. Of the select states with the ability to analyze readmissions, we chose California, New York, and Florida because of their large and diverse populations.

METHODS

Study Design and Patient Population

This retrospective cohort study defined the index hospitalization as the first acute-care inpatient hospital stay for adults age ≥ 40 years with a principal discharge diagnosis (Dx1) of heart failure (ICD-9-CM diagnosis codes 398.91, 402.01, 402.11, 402.91, 404.01, 404.11, 404.03, 404.13, 404.91, 404.93, and 428.x)15 from 2007 through 2011 using the SID from California, New York, and Florida. Patients were excluded if age, gender, patient-level encrypted identifier, or length of hospital stay was missing from the SID, or if the patient died during the index hospitalization. Patients were also excluded if the index hospitalization discharge was in the fourth quarter of 2011 to ensure at least a 30-day window to capture readmissions. If patients with a primary heart failure admission in 2009 – 2011 had a primary heart failure admission within the prior 2 years that prior admission would have been counted as their index admission. Therefore, patients admitted in 2007 or 2008 who had an admission in the preceding 24 months with a primary diagnosis of heart failure were excluded to ensure that the index hospitalization for heart failure was not preceded by a recent heart failure hospitalization across all years of the study. All admissions to non-community hospitals16 (e.g., inpatient psychiatry, drug rehabilitation, long-term care) were excluded. To reduce loss to follow-up, we also excluded index hospitalizations for non-state residents. Patients with an index hospitalization length of stay > 180 days, a rare population with disproportionate risk of readmission, were also excluded. An acute care hospital discharge and readmission on the same day was treated as a hospital transfer and a continuation of the index hospitalization. Additionally, if discharge disposition was “transfer to short-term hospital,” and the first readmission occurred the next day, then the readmission was also treated as an index hospitalization transfer.17 See Supplementary Material 1 for a schema of the cohort generation.

The Washington University Human Research Protection Office exempted this project from Institutional Review Board oversight as the Data Use Agreement prohibits attempting to re-identify participants.

Definition of Comorbidities

Individual patient comorbidities and secondary diagnoses of heart failure were identified from all hospital admissions during the previous two years, up to and including the index hospitalization. Comorbidities were characterized using the HCUP Clinical Classifications Software18,19 and the comorbidity classification scheme of Elixhauser et al.20 Specifically, the ICD-9-CM codes used for fluid and electrolyte disorders, chronic deficiency anemia, and chronic kidney disease were 276.0 – 276.9, 280.1 – 281.9 plus 285.9, and 585.1 – 585.9 plus 792.5, V420, V451, V451.1, V451.2, V56.0, V56.1, V56.2, V563.1, V563.2, and V56.8, respectively.

We used the HCUP cost-to-charge ratio files to convert total charges to total costs, and adjusted costs to 2011 dollars using the medical care component of the Consumer Price Index (CPI).21

Outcomes

The primary outcome was all-cause 30-day hospital readmission. Secondary outcomes were early (7 days) and later (8–30 days) readmission and 7-, 8–30, and 30-day readmissions for heart failure versus other causes among those patients with a 30-day admission.

Statistical Analysis

Baseline characteristics between groups were compared using Chi square tests for categorical variables and Student’s t-tests and Wilcoxon’s tests for normally and non-normally distributed continuous variables, respectively. All p-values were two-sided and values <0.01 were considered statistically significant. Given the large sample size, Standardized Mean Differences (SMD) between groups, which reflect effect sizes and are not influenced by sample size, were calculated.22 Absolute values of the SMD are reported, with a value ≥ 0.10 suggestive of a meaningful difference.23 Multivariable logistic regression using a modified Poisson regression model that included variables for age, gender, race, comorbid conditions, insurer, discharge disposition, and length of stay was used to analyze 7-day, 8–30 day, and 30-day readmissions.24 Variables with very low prevalence (<4%) were not included in the model. SAS version 9.3 (SAS Institute Inc, Cary, NC) was used for all statistical analysis.

RESULTS

Baseline Demographics

The SIDs for California, New York, and Florida from 2007–2011 contained 547,068 patients who met the inclusion/exclusion criteria with an index hospitalization for heart failure. The cohort was 50.7% female with a mean age of 74.7 years (SD 14.1) (Table 1). Approximately two thirds of the patients were white, one in seven black, and one in eight Hispanic. California, Florida, and New York comprised 38.8%, 32.6%, and 28.6% of the total cohort, respectively. In the 2 years prior to the index hospitalization, 327,325 patients (59.8%) had at least 1 hospitalization with a non-heart failure primary diagnosis. Of these, 181,257 (33.1% of total cohort) had a prior admission that included heart failure as a secondary diagnosis. The median length of stay for the index hospitalization was 4 days (IQR 2 – 7) and the median cost of the index admission was $7,580 (IQR $4,693 - $13,430).

Table 1.

Baseline characteristics of patients without vs. with 7-, 8–30-, and 30-day all-cause readmission.

7-day All- Cause Readmission N (%)(40,046) 8–30-day All- Cause Readmission N (%)(77,077) SMD * 7 vs 8–30 days 30-d All- Cause Readmission N (%)(117,123) No 30-d Readmission N (%)(429,945) SMD * 30- days vs. None
Age Category 0.03 0.03
40–64 years 8,333 (20.8) 16,709 (21.7) −0.02 25,042 (21.4) 99,866 (23.2) −0.04
65–74 years 7,804 (19.5) 15,502 (20.1) −0.02 23,306 (19.9) 83,734 (19.5) 0.01
75–84 years 12,788 (31.9) 24,325 (31.6) 0.01 37,113 (31.7) 129,109 (30.0) 0.04
≥ 85 years 11,121 (27.8) 20,541 (26.6) 0.03 31,662 (27.0) 117,236 (27.3) −0.01
Female 20,116 (50.2) 39,469 (51.2) −0.02 59,585 (50.9) 217,980 (50.7) 0.00
Race
White 26,172 (65.4) 49,816 (64.6) 0.02 75,988 (64.9) 281,918 (65.6) −0.01
Black 5,134 (12.8) 10,791 (14.0) −0.03 15,925 (13.6) 57,969 (13.5) 0.00
Hispanic 5,359 (13.4) 10,270 (13.3) 0.00 15,629 (13.3) 53,311 (12.4) 0.03
Asian/Pacific Islander, Native American, 3,381 (8.4) 6,200 (8.0) 0.01 9,581 (8.2) 36,747 (8.5) −0.01
Other, Missing
Acute Secondary Diagnoses Coded on Index Hospitalization
Acute renal failure 7,788 (19.4) 13,725 (17.8) 0.04 21,513 (18.4) 60,063 (14) 0.12
Pleural effusion 2,908 (7.3) 5,483 (7.1) 0.01 8,391 (7.2) 24,098 (5.6) 0.06
Acute myocardial infarction 2,183 (5.5) 3,509 (4.6) 0.04 5,692 (4.9) 15,544 (3.6) 0.06
Acute exacerbation of chronic lung disease 5,783 (14.4) 11,091 (14.4) 0.00 16,874 (14.4) 53,585 (12.5) 0.06
Pneumonia 6,223 (15.5) 11,574 (15.0) 0.01 17,797 (15.2) 58,158 (13.5) 0.05
Supraventricular tachycardia 16,180 (40.4) 31,570 (41.0) −0.01 47,750 (40.8) 167,509 (39.0) 0.04
Cardiac arrest and ventricular fibrillation 2,063 (5.2) 3,774 (4.9) 0.01 5,837 (5.0) 20,314 (4.7) 0.01
Acute Illnesses coded as Primary or any Secondary Dx within 90 days before Index Hospitalization
Acute renal failure 4,291 (10.7) 8,129 (10.5) 0.01 12,420 (10.6) 25,460 (5.9) 0.17
Supraventricular tachycardia 6,372 (15.9) 12,309 (16) 0.00 18,681 (15.9) 47,012 (10.9) 0.15
Pneumonia 3,222 (8.0) 6,169 (8.0) 0.00 9,391 (8.0) 19,883 (4.6) 0.14
Acute exacerbation of chronic lung disease 2,472 (6.2) 5,025 (6.5) −0.01 7,497 (6.4) 15,073 (3.5) 0.13
Clinical sepsis 1,788 (4.5) 3,102 (4.0) 0.02 4,890 (4.2) 8,811 (2.0) 0.12
Conduction disorders 3,547 (8.9) 6,782 (8.8) 0.00 10,329 (8.8) 25,203 (5.9) 0.11
Acute myocardial infarction 2,568 (6.4) 4,919 (6.4) 0.00 7,487 (6.4) 17,026 (4.0) 0.11
Chronic conditions coded at any point within 2 years before or on Index Hospitalization
Prior secondary diagnosis of heart failure 16,212 (40.5) 32,166 (41.7) −0.03 48,378 (41.3) 132,879 (30.9) 0.22
Chronic electrolyte disorder 21,384 (53.4) 40,051 (52.0) 0.03 61,435 (52.5) 179,131 (41.7) 0.22
Chronic deficiency anemia 19,748 (49.3) 38,225 (49.6) −0.01 57,973 (49.5) 167,491 (39) 0.21
Chronic kidney disease 18,778 (46.9) 35,872 (46.5) 0.01 54,650 (46.7) 158,448 (36.9) 0.20
Chronic complicated hypertension 18,353 (45.8) 35,233 (45.7) 0.00 53,586 (45.8) 156,104 (36.3) 0.19
Chronic lung disease 18,340 (45.8) 35, 367 (45.9) 0.00 53,707 (45.9) 171,540 (39.9) 0.12
Chronic coronary artery disease 26,347 (65.8) 50,681 (65.8) 0.00 77,028 (65.8) 258,956 (60.2) 0.11
Chronic weight loss 3,656 (9.1) 6,722 (8.7) 0.01 10,378 (8.9) 25,278 (5.9) 0.11
Chronic peripheral vascular disease 7,758 (19.4) 14,939 (19.4) 0.00 22,697 (19.4) 65,498 (15.2) 0.11
Diabetes Mellitus 20,050 (50.1) 38,464 (49.9) 0.00 58,514 (50.0) 192,765 (44.8) 0.10
Depression 6,670 (16.7) 12,877 (16.7) 0.00 19,547 (16.7) 56,767 (13.2) 0.10
Neurologic disorders 5,477 (13.7) 10,165 (13.2) 0.01 15,642 (13.4) 45,529 (10.6) 0.09
History of tobacco use 14,321 (35.8) 28,236 (36.6) −0.02 42,557 (36.3) 142,326 (33.1) 0.07
Pulmonary circulation disease 8,515 (21.3) 17,009 (22.1) −0.02 25,524 (21.8) 82,186 (19.1) 0.07
Chronic valvular heart disease 14,809 (37) 29,315 (38) −0.02 44,124 (37.7) 149,005 (34.7) 0.06
Chronic disorders of lipoid metabolism 22,889 (57.2) 44,209 (57.4) 0.00 67,098 (57.3) 233,922 (54.4) 0.06
History of transient ischemic attack 4,490 (11.2) 8,625 (11.2) 0.00 13,115 (11.2) 40,585 (9.4) 0.06
Hypothyroidism 7,971 (19.9) 15,682 (20.3) −0.01 23,653 (20.2) 77,830 (18.1) 0.05
History of past non-nompliance 4,370 (10.9) 8,846 (11.5) −0.02 13,216 (11.3) 42,005 (9.8) 0.05
Obesity 7,714 (19.3) 15,109 (19.6) −0.01 22,823 (19.5) 84,490 (19.7) 0.00
Chronic Essential Hypertension 24,102 (60.2) 46,912 (60.9) −0.01 71,014 (60.6) 261,864 (60.9) −0.01
Expected Primary Payer
Medicare 31,634 (79.0) 60,615 (78.6) 0.01 92,249 (78.8) 324,416 (75.5) 0.08
Medicaid 3,228 (8.1) 6,515 (8.5) −0.01 9,743 (8.3) 31,735 (7.4) 0.03
Private Insurance 3,652 (9.1) 6,888 (8.9) 0.01 10,540 (9.0) 50,470 (11.7) −0.09
Self-Pay, No Charge, Other, Missing 1,532 (3.8) 3,059 (4.0) −0.01 4,591 (3.9) 23,324 (5.4) −0.07
Medicare, age <65 2,615 (6.5) 5,243 (6.8) −0.01 7,858 (6.7) 23,873 (5.6) 0.05
Discharge Disposition
Routine Discharge 19,015 (47.5) 38,829 (50.4) −0.06 57,844 (49.4) 250,806 (58.3) −0.18
Transfer to Short-term Hospital 242 (0.6) 459 (0.6) 0.00 701 (0.6) 3,593 (0.8) −0.03
Transfer Other: Includes SNF, Intermediate 9,476 (23.7) 17,976 (23.3) 0.01 27,452 (23.4) 74,906 (17.4) 0.15
Care Facility, Another type of facility
Home Health Care 10,239 (25.6) 18,592 (24.1) 0.03 28,831 (24.6) 94,866 (22.1) 0.06
Against Medical Advice 1,038 (2.6) 1,173 (1.5) 0.08 2,211 (1.9) 5,012 (1.2) 0.06
Discharge Alive, Destination Unknown or Missing 36 (0.1) 48 (0.1) 0.01 84 (0.1) 762 (0.2) −0.03
Length of Stay
LOS Quartile 1 8,288 (20.7) 15,661 (20.3) 0.01 23,949 (20.4) 115,846 (26.9) −0.15
LOS Quartile 2 11,138 (27.8) 22,251 (28.9) −0.02 33,389 (28.5) 133,724 (31.1) −0.06
LOS Quartile 3 9,720 (24.3) 19,699 (25.6) −0.03 29,419 (25.1) 100,056 (23.3) 0.04
LOS Quartile 4 10,900 (27.2) 19,466 (25.3) 0.04 30,366 (25.9) 80,319 (18.7) 0.17
LOS in Days, Median (IQR) 5 (3, 8) 5 (3, 8) 0.05 5 (3, 8) 4 (2, 6) 0.17
Median (IQ Range) cost of index hospitalization 48,417 (5,059, 15,386) $8,170 (5,012, 14,386) 0.06 $8,251 (5,028, 14,695) $7,409 (4,611, 13,074) 0.09
Transferred during index presentation 2,047 (5.1) 3,467 (4.5) 0.03 5,514 (4.7) 17,185 (4.0) 0.03
Readmitted to same hospital as index hospitalization 30,550 (76.3) 59,116 (76.7) −0.01 89,666 (76.6) N.A. N.A.
Index admission through Emergency Department 35,620 (88.9) 68,185 (88.5) 0.02 103,805 (88.6) 369,391 (85.9) 0.08
Readmission through Emergency Department 35,097 (87.6) 64,760 (84.0) 0.10 99,857 (85.3) N.A. N.A.
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*

Standardized Mean Difference (SMD), where absolute value ≥ 0.10 is considered clinically meaningful.

All-Cause Readmission

Seven percent of patients were readmitted within 7 days and 14% in the remaining 23 days. Overall, all-cause 30-day readmission occurred in 117,123 (21.4%) patients and the daily readmission rate decreased steadily over the 30-day window (Figure 1). The all-cause 30-day readmission rates in California, Florida, and New York were 20.7%, 21.9%, and 21.9%, respectively. Compared to non-readmitted patients, readmitted patients were significantly more likely to have the following chronic medical conditions: a prior admission with heart failure as a secondary diagnosis, a history of fluid and electrolyte disorders, chronic deficiency anemia, and chronic kidney disease (Table 1). While the number of index hospitalizations with a primary diagnosis of heart failure decreased from 2007 through 2011, the proportion of patients readmitted within 30-days was consistently approximately one in 5 (Supplementary Material 2). There were no significant clinical differences at baseline between those patients who had their first readmission in the first 7 days after discharge versus those in the next 23 days (Table 1).

Figure 1.

Figure 1

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Daily rate of readmission for All-Cause (green line), Non-HF (red line), and HF (blue line). The denominator was adjusted daily to account for patients remaining eligible for a first readmission.

30-day Readmissions for Heart Failure vs. Other Diagnoses

Among patients with a 30-day readmission, 35,450 (30.3%) were readmitted with a primary diagnosis of heart failure, while 69.7% were readmitted with a primary diagnosis other than heart failure. The median time to 30-day readmission for both heart failure and non-heart failure causes was 12 days. The proportion of patients readmitted for heart failure versus non-heart failure on each day was consistent across the 30-day readmission window (Figure 2). Patients with a 30-day readmission had similar comorbidity profiles regardless of whether they were readmitted for heart failure or a non-heart failure cause or whether they were admitted before or after 7 days. Patients with a heart failure readmission were more likely to be readmitted through the Emergency Department and to the same hospital as the index hospitalization. Additionally, compared to those readmitted for a non-heart failure diagnosis, individuals readmitted within 30 days with a primary diagnosis of heart failure had shorter median index hospitalization lengths of stay (4, IQR 3-7, vs. 5, IQR 3-8 days) with correspondingly lower median index hospitalization costs ($7,738, IQR 4,737–13,575 vs. $8,479, IQR 5,160–15,217). The daily proportion of patients with heart failure vs. non-heart failure readmission diagnoses was similar when stratified by age < 65 versus ≥ 65 years (Supplementary Material 3).

Figure 2.

Figure 2

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Daily readmissions presented as a proportion of HF (blue) and non-HF (red).

Non-Heart Failure Readmission Diagnoses

The most common primary diagnoses for non-heart failure readmissions within 30 days were other cardiovascular conditions (14.9%), pulmonary disorders other than pneumonia (8.5%), acute infections (7.7%), hematologic and oncologic conditions (6.7%), and renal/genitourinary conditions (5.5%) (Figure 3A). When stratified by age ≥ 65 and <65 years and by time to readmission (7 days versus 8–30 days), these remained as the top 5 non-heart failure primary diagnoses (Supplementary Material 4 and 5). Common non-heart failure cardiovascular readmission diagnoses included arrhythmias, coronary artery disease, acute myocardial infarction, heart valve disorders, and chest pain (Figure 3B). The 4 most common infectious processes were clinical sepsis, pneumonia, urinary tract infection, and Clostridium difficile, and made up 52.5%, 18.3%, 17.8%, and 11.4% of infectious diagnoses, respectively. Pulmonary disorders included acute exacerbation of chronic lung disease and acute respiratory failure.

Figure 3.

Figure 3

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A) The most common primary diagnoses on 30-day readmission after hospitalization for heart failure. B) Detailed view of the non-heart failure cardiovascular causes of readmission.

Univariate Analysis

Univariate odds ratio (OR) data are shown in Table 3. Clinical sepsis within 90 days prior to index hospitalization was the comorbidity most strongly associated with 7-day (OR 1.94, 95% CI 1.85, 2.04), 8-30- (OR 1.82, 95% CI 1.74, 1.89), and overall 30-day (OR 2.08, 95% CI 2.01, 2.16) readmission. Leaving against medical advice was far more strongly associated with early (7-day) rather than later (8-30-day) readmission. In univariate analysis, age was not strongly associated with readmission.

Table 3.

Univariate and Multivariate Analysis of Readmission Risk Factors. Comorbidities sorted by 30-day multivariate Odds Ratio

7 Days 8–30 Days 30 Days
Univariate OR (95% CI) Multivariate OR (95% CI) Univariate OR (95% CI) Multivariate OR (95% CI) Univariate OR (95% CI) Multivariate OR (95% CI)
Age Category
40–64 years 0.88 (0.86, 0.9) 0.89 (0.86, 0.93) 0.93 (0.91, 0.94) 0.88 (0.86, 0.91) 0.9 (0.88, 0.91) 0.88 (0.85 , 0.9)
65–74 years 0.99 (0.97, 1.02) Reference 1.04 (1.02, 1.06) Reference 1.03 (1.01, 1.04) Reference
75–84 years 1.08 (1.06, 1.11) 1.04 (1.01, 1.08) 1.07 (1.05, 1.08) 0.99 (0.97, 1.02) 1.08 (1.07, 1.1) 1.01 (0.99 , 1.03)
≥ 85 years 1.03 (1.01, 1.05) 1.02 (0.99, 1.05) 0.97 (0.95, 0.98) 0.93 (0.91, 0.96) 0.99 (0.97, 1) 0.96 (0.94 , 0.98)
Female 0.98 (0.96, 1) 0.95 (0.93, 0.97) 1.02 (1.01, 1.04) 0.99 (0.97, 1.01) 1.01 (0.99, 1.02) 0.97 (0.96 , 0.98)
Race
White 1 (0.98, 1.02) Reference 0.96 (0.95, 0.98) Reference 0.97 (0.96, 0.98) Reference
Black 0.94 (0.91, 0.97) 0.96 (0.93, 1) 1.05 (1.03, 1.07) 1.06 (1.03, 1.08) 1.01 (0.99, 1.03) 1.02 (0.99 , 1.04)
Hispanic 1.08 (1.05, 1.11) 1.04 (1, 1.07) 1.08 (1.05, 1.1) 1.06 (1.04, 1.09) 1.09 (1.07, 1.11) 1.05 (1.03 , 1.08)
Asian/Pacific Islander, Native American, 1 (0.96, 1.03) 0.98 (0.94, 1.02) 0.94 (0.91, 0.96) 0.95 (0.93, 0.98) 0.95 (0.93, 0.98) 0.95 (0.93 , 0.98)
Other, Missing
Acute Secondary Diagnoses Coded on Index Hospitalization
Acute myocardial infarction 1.48 (1.41, 1.55) 1.23 (1.17, 1.29) 1.22 (1.17, 1.26) N.S.M.V. 1.36 (1.32, 1.4) 1.12 (1.09, 1.16)
Pleural effusion 1.26 (1.21, 1.31) 1.08 (1.03, 1.12) 1.26 (1.22, 1.29) 1.09 (1.06, 1.13) 1.3 (1.27, 1.33) 1.1 (1.07, 1.13)
Acute renal failure 1.42 (1.38, 1.45) 1.11 (1.08, 1.14) 1.28 (1.26, 1.31) N.S.M.V. 1.39 (1.36, 1.41) 1.06 (1.04, 1.08)
Supraventricular tachycardia 1.05 (1.03, 1.07) N.S.M.V. 1.08 (1.06, 1.1) 1.05 (1.03, 1.07) 1.08 (1.06, 1.09) 1.03 (1.02, 1.05)
Pneumonia 1.15 (1.12, 1.19) N.S.M.V. 1.11 (1.09, 1.14) 0.97 (0.95, 0.99) 1.15 (1.12, 1.17) 0.97 (0.95, 0.98)
Acute exacerbation of chronic lung disease 1.15 (1.12, 1.19) N.S.M.V. 1.16 (1.14, 1.19) N.S.M.V. 1.18 (1.16, 1.2) N.S.M.V.
Cardiac arrest and ventricular fibrillation 1.09 (1.04, 1.14) N.S.M.V. 1.03 (0.99, 1.07) N.S.U.V. 1.06 (1.03, 1.09) N.S.M.V.
Acute Illnesses coded as Primary or any Secondary Dx within 90 days before Index Hospitalization
Acute exacerbation of chronic lung disease 1.59 (1.53, 1.66) 1.15 (1.1, 1.21) 1.8 (1.74, 1.86) 1.25 (1.21, 1.3) 1.88 (1.83, 1.94) 1.27 (1.23, 1.31)
Clinical sepsis 1.94 (1.85, 2.04) 1.26 (1.19, 1.33) 1.82 (1.74, 1.89) 1.12 (1.07, 1.17) 2.08 (2.01, 2.16) 1.22 (1.18, 1.27)
Acute myocardial infarction 1.51 (1.45, 1.58) 1.1 (1.05, 1.15) 1.57 (1.52, 1.62) 1.17 (1.13, 1.21) 1.66 (1.61, 1.7) 1.16 (1.13, 1.2)
Pneumonia 1.62 (1.55, 1.68) 1.08 (1.04, 1.13) 1.68 (1.63, 1.73) 1.1 (1.06, 1.13) 1.8 (1.75, 1.84) 1.11 (1.08, 1.15)
Conduction disorders 1.44 (1.39, 1.5) 1.09 (1.05, 1.14) 1.48 (1.44, 1.52) 1.08 (1.05, 1.11) 1.55 (1.52, 1.59) 1.1 (1.07, 1.13)
Acute renal failure 1.69 (1.64, 1.75) 1.07 (1.03, 1.11) 1.74 (1.7, 1.79) 1.09 (1.06, 1.12) 1.88 (1.84, 1.93) 1.1 (1.08, 1.13)
Supraventricular tachycardia 1.43 (1.39, 1.47) 1.09 (1.05, 1.12) 1.48 (1.45, 1.52) 1.07 (1.04, 1.1) 1.55 (1.52, 1.57) 1.09 (1.06, 1.11)
Chronic conditions coded at any point within 2 years before or on Index Hospitalization
Chronic deficiency anemia 1.42 (1.4, 1.45) 1.1 (1.08, 1.13) 1.49 (1.46, 1.51) 1.16 (1.14, 1.18) 1.54 (1.52, 1.56) 1.16 (1.14, 1.17)
Chronic kidney disease 1.42 (1.39, 1.45) 1.14 (1.11, 1.16) 1.44 (1.42, 1.46) 1.14 (1.11, 1.18) 1.5 (1.48, 1.52) 1.16 (1.13, 1.18)
Chronic electrolyte disorders 1.5 (1.47, 1.54) 1.17 (1.15, 1.2) 1.45 (1.43, 1.48) 1.1 (1.09, 1.12) 1.54 (1.52, 1.56) 1.15 (1.13, 1.16)
Prior secondary diagnosis of heart failure 1.41 (1.38, 1.44) 1.08 (1.05, 1.11) 1.54 (1.52, 1.57) 1.15 (1.13, 1.17) 1.57 (1.55, 1.59) 1.14 (1.12, 1.16)
Chronic weight loss 1.49 (1.44, 1.55) 1.11 (1.07, 1.15) 1.46 (1.42, 1.5) 1.09 (1.06, 1.12) 1.56 (1.52, 1.59) 1.12 (1.09, 1.15)
Depression 1.26 (1.22, 1.29) 1.07 (1.04, 1.1) 1.29 (1.26, 1.31) 1.07 (1.05, 1.1) 1.32 (1.29, 1.34) 1.09 (1.07, 1.11)
History of past non-nompliance 1.1 (1.06, 1.14) 1.04 (1.01, 1.08) 1.18 (1.16, 1.21) 1.1 (1.07, 1.13) 1.17 (1.15, 1.2) 1.09 (1.07, 1.12)
Chronic peripheral vascular disease 1.27 (1.24, 1.31) 1.05 (1.02, 1.08) 1.3 (1.28, 1.33) 1.06 (1.04, 1.08) 1.34 (1.32, 1.36) 1.07 (1.05, 1.09)
Chronic valvular heart disease 1.08 (1.06, 1.1) N.S.M.V. 1.15 (1.13, 1.17) 1.08 (1.06, 1.1) 1.14 (1.12, 1.16) 1.07 (1.05, 1.08)
Chronic lung disease 1.23 (1.2, 1.25) 1.06 (1.04, 1.09) 1.25 (1.23, 1.27) 1.05 (1.03, 1.07) 1.28 (1.26, 1.29) 1.06 (1.05, 1.08)
Chronic coronary artery disease 1.23 (1.2, 1.25) 1.05 (1.03, 1.08) 1.24 (1.22, 1.26) 1.06 (1.04, 1.08) 1.27 (1.25, 1.29) 1.06 (1.05, 1.08)
Diabetes Mellitus 1.2 (1.17, 1.22) 1.06 (1.04, 1.09) 1.2 (1.19, 1.22) 1.05 (1.03, 1.07) 1.23 (1.21, 1.24) 1.06 (1.05, 1.08)
History of tobacco use 1.1 (1.08, 1.12) N.S.M.V. 1.16 (1.14, 1.17) 1.07 (1.05, 1.09) 1.15 (1.14, 1.17) 1.06 (1.04, 1.08)
Neurologic Disorders 1.28 (1.25, 1.32) 1.07 (1.04, 1.1) 1.25 (1.22, 1.28) 1.04 (1.02, 1.07) 1.3 (1.28, 1.33) 1.06 (1.04, 1.08)
Hypothyroidism 1.1 (1.07, 1.13) N.S.M.V. 1.14 (1.12, 1.17) 1.05 (1.03, 1.07) 1.14 (1.13, 1.16) 1.04 (1.03, 1.06)
Chronic complicated hypertension 1.4 (1.37, 1.42) N.S.M.V. 1.43 (1.4, 1.45) 1.03 (1.01, 1.06) 1.48 (1.46, 1.5) 1.03 (1.01, 1.05)
Chronic disorders of lipoid metabolism 1.1 (1.08, 1.12) N.S.M.V. 1.12 (1.1, 1.13) N.S.M.V. 1.12 (1.11, 1.14) N.S.M.V.
Chronic Essential Hypertension 0.97 (0.95, 0.99) N.S.M.V. 1 (0.99, 1.02) N.S.U.V. 0.99 (0.98, 1) N.S.U.V.
History of transient ischemic attack 1.17 (1.14, 1.21) N.S.M.V. 1.19 (1.16, 1.22) N.S.M.V. 1.21 (1.18, 1.24) N.S.M.V.
Obesity 0.98 (0.95, 1) N.S.U.V. 1 (0.98, 1.02) N.S.U.V. 0.99 (0.97, 1.01) N.S.U.V.
Pulmonary circulation disease 1.11 (1.08, 1.14) N.S.M.V. 1.18 (1.16, 1.21) N.S.M.V. 1.18 (1.16, 1.2) N.S.M.V.
Expected Primary Payer
Medicare 1.19 (1.16, 1.22) N.A. 1.18 (1.16, 1.2) N.A. 1.21 (1.19, 1.23) N.A.
Medicaid 1.07 (1.03, 1.12) 1.17 (1.12, 1.23) 1.15 (1.12, 1.18) 1.24 (1.2, 1.28) 1.14 (1.11, 1.17) 1.24 (1.2 , 1.27)
Private Insurance 0.79 (0.76, 0.81) Reference 0.75 (0.73, 0.77) Reference 0.74 (0.73, 0.76) Reference
Self-Pay, No Charge, Other, Missing 0.72 (0.69, 0.76) 0.92 (0.87, 0.98) 0.74 (0.71, 0.77) 0.95 (0.91, 0.99) 0.71 (0.69, 0.73) 0.93 (0.89 , 0.96)
Medicare, age <65 1.15 (1.1, 1.2) 1.22 (1.15, 1.29) 1.22 (1.19, 1.26) 1.26 (1.21, 1.31) 1.22 (1.19, 1.26) 1.28 (1.24 , 1.32)
Discharge Disposition
Routine Discharge 0.68 (0.66, 0.69) Reference 0.75 (0.74, 0.76) Reference 0.7 (0.69, 0.71) Reference
Transfer to Short-term Hospital 0.75 (0.66, 0.86) 0.87 (0.76, 0.99) 0.73 (0.66, 0.8) 0.83 (0.75, 0.92) 0.71 (0.66, 0.77) 0.82 (0.76 , 0.9)
Transfer Other: Includes SNF, 1.38 (1.35, 1.42) 1.18 (1.15, 1.22) 1.39 (1.36, 1.42) 1.18 (1.16, 1.21) 1.45 (1.43, 1.47) 1.21 (1.19 , 1.24)
Intermediate Care Facility, Another type of facility
Home Health Care 1.19 (1.16, 1.22) 1.17 (1.14, 1.2) 1.1 (1.08, 1.12) 1.07 (1.04, 1.09) 1.15 (1.14, 1.17) 1.12 (1.1 , 1.14)
Against Medical Advice 2.15 (2.02, 2.3) 2.59 (2.42, 2.77) 1.19 (1.11, 1.26) 1.36 (1.27, 1.45) 1.63 (1.55, 1.72) 1.94 (1.85 , 2.05)
Discharge Alive, Destination Unknown or Missing 0.56 (0.4, 0.79) 0.54 (0.39, 0.75) 0.37 (0.27, 0.49) 0.36 (0.27, 0.48) 0.4 (0.32, 0.51) 0.39 (0.31 , 0.48)
Length of Stay
LOS Quartile 1 0.75 (0.73, 0.76) Reference 0.71 (0.7, 0.72) Reference 0.7 (0.69, 0.71) Reference
LOS Quartile 2 0.87 (0.85, 0.89) 1.07 (1.04, 1.1) 0.91 (0.9, 0.93) 1.14 (1.11, 1.17) 0.88 (0.87, 0.9) 1.13 (1.1 , 1.15)
LOS Quartile 3 1.04 (1.01, 1.06) 1.14 (1.1, 1.17) 1.13 (1.11, 1.15) 1.26 (1.23, 1.29) 1.11 (1.09, 1.12) 1.24 (1.21 , 1.26)
LOS Quartile 4 1.53 (1.49, 1.56) 1.38 (1.33, 1.43) 1.4 (1.38, 1.43) 1.38 (1.35, 1.42) 1.52 (1.5, 1.55) 1.44 (1.41 , 1.48)
Transferred during index presentation 1.27 (1.21, 1.33) N.S.M.V. 1.1 (1.06, 1.15) 0.91 (0.87, 0.95) 1.19 (1.15, 1.22) 0.92 (0.89 , 0.95)
Index admission through Emergency Department 1.28 (1.24, 1.32) 1.16 (1.13, 1.2) 1.23 (1.2, 1.26) 1.14 (1.11, 1.16) 1.28 (1.25, 1.3) 1.16 (1.14 , 1.19)
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N.S.U.V. = Non-significant in univariate analysis. N.S.M.V. = Non-significant in multivariate analysis.

Multivariable Analysis

Results of multivariable analysis are provided in Table 3. After multivariable adjustment, clinical conditions present on admission within 90 days prior to index hospitalization tended to be more strongly associated with both 7-day and 30-day readmission as opposed to acute or chronic conditions. Discharge against medical advice had the highest overall odds of both 7- (OR 2.59, 95% CI 2.42, 2.77) and 30-day (OR 1.94, 95% CI 1.85, 2.05) readmission.

DISCUSSION

With nearly 550,000 patients from 3 populous and diverse states accumulated over 5 years, this is the largest all-payer cohort study on heart failure readmissions reported to date. We found that more than 1 in 5 patients had a 30-day all-cause readmission after index hospitalization for heart failure, and the median time to 30-day readmission was 12 days. The majority of readmissions (69.7%) were for non-heart failure diagnoses. Over the 30-day post-discharge window, the daily rate of readmission decreased steadily, while the ratio of heart failure to non-heart failure readmission diagnoses remained constant. These findings were true for patients < 65 years as well as those ≥ 65 years. There were no differences in age, gender, ethnicity, or medical comorbidities at baseline of those admitted within 7 days as compared to those admitted in the next 23 days, nor were there differences in the top reasons for readmission. Interestingly, in the current study only discharge against medical advice was more significant as a predictor of early versus later hospital readmission. The number of index hospitalizations decreased each year, yet the rate of all cause 30-day readmissions remained consistent. While patients experiencing a readmission within 30 days tended to have lengthier and more costly index hospitalizations, those readmitted with a primary diagnosis of heart failure had shorter index hospitalization stays and lower index hospitalization costs compared to those readmitted for a non-heart failure diagnosis. This may reflect a tension between reducing heart failure hospital length of stay at the expense of subsequent readmission.25,26

Our data are largely in agreement with the findings of other retrospective analyses of 30-day readmissions following hospitalization for heart failure with respect to both readmission rates and readmission diagnoses.3,4,25 Interestingly, the rates of 30-day readmission have not changed appreciably over the years. In a study of 30-day readmissions after heart failure hospitalization using 2004–2006 Medicare claims data, Dharmarajan et al expanded on earlier Medicare data25 and showed that 35.2% of readmissions were for heart failure, and the median time to readmission was also 12 days. Our analysis further extends these findings from the Medicare population to a much broader population both in terms of age and payer mix, with 24% of subjects in this analysis under age 65 and 25% having a payer other than Medicare. This study builds on Ranasinghe et al’s analysis of the California SID from 2007 – 2009 by evaluating all ages ≥40 over a broader time range and a more extensive geographic area. Notably, we found that readmission timing and etiologies were similar in patients older or younger than age 65 years. Contrary to a study of 4584 MarketScan Commercial and Medicaid Administrative Claims Database patients from 2005–2008,27 we did not find statistically different rates of readmission based on payer. Overall, this study helps to generalize the findings of previous, more focused cohorts by capturing a broader range of patient ages, demographics, and payers.

This analysis demonstrates 4 key insights that would ideally power prospective interventions to reduce readmissions and overall morbidity among patients hospitalized with heart failure. First, the readmission risk is highest immediately post-discharge (Figure 1), and the majority of 30-day readmissions occur within the first 2 weeks. Second, more than two-thirds of readmissions are for conditions other than heart failure. Third, these trends are true for patients < 65 years as well as for those age 65 or older. Finally, clinical conditions did not strongly predict early versus later readmission. Several of these patterns of readmission diagnoses have been reported previously,3,4,28,29 but never simultaneously in such a broad, all-payer cohort of all adults aged ≥ 40.

The major burden of non-heart failure readmissions and the high prevalence of comorbidities among those with and without readmission strongly indicate a need to focus on non-heart failure conditions in the setting of acute heart failure hospitalization. Only 6.5% (35,450/547,068) of the study cohort was readmitted within 30 days for heart failure, suggesting that heart failure is being well treated through aggressive inpatient management and intensive post-discharge care. Since hemodynamic monitoring data suggest that physiologic decompensation may begin upwards of 2 weeks prior to onset of symptoms,30 the heightened risk of early readmission (i.e., less than 2 weeks) for non-heart failure causes underscores the need to broaden multidisciplinary interventions that begin during hospitalization and bridge the transition to home. Merely focusing on residual congestion and optimization of chronic heart failure therapies will not likely yield significant additional reductions in 30-day readmissions.

The present analysis highlights the critical burden of potentially unaddressed or unmasked non-heart failure medical diagnoses in the hospitalized heart failure population, a burden that will inevitably increase as the population ages.31–33 Further, these data suggest that the admission itself may be a risk factor for readmission. For example, a substantial proportion of readmissions are for potentially iatrogenic or hospital-acquired infectious causes, such as urinary tract infection and Clostridium difficile infection. Closer surveillance for these conditions may allow early identification and treatment in the outpatient setting, thereby obviating the need for readmission. The resources that have been brought to bear on reducing readmissions for heart failure need to be expanded to cover the non-heart failure conditions that frequently lead to readmission, and future analyses of the population-level impact of targeting key conditions associated with highest risk for readmissions and other adverse outcomes in hospitalized heart failure patients should be undertaken.

This study has some limitations. Data more recent than 2011 were unavailable at the time of the analysis. While administrative data are observational and lack the granularity of prospectively collected clinical data, the large and diverse HCUP population with broad scope directs attention towards areas with the greatest epidemiologic and societal consequences. Another limitation is the adjudication of the primary diagnosis versus a secondary diagnosis as the primary reason for admission. In a study of coding accuracy, Nouraei et al found that in nearly 9000 patient discharge records, clinician and clinical coder concordance for acute heart failure was excellent (kappa 0.92, 95% CI 0.88–0.95).34 Despite potential coding inaccuracies and lack of clinical detail, assessment of clinical outcomes such as mortality and readmission rates using administrative data have been validated against medical records35 as well as prospective registries.36,37 Data for these analyses were derived from 3 states (CA, NY, and FL); generalizability to other states requires further study. Finally, all data were collected prior to implementation of the Hospital Readmission Reduction Program under the Affordable Care Act; the impact of this program on readmissions following hospitalization for heart failure remains to be established.

CONCLUSION

In this large all-payer cohort, ~70% of 30-day readmissions were for non-heart failure causes, and the median time to 30-day readmission was 12 days. Focusing on competing non-heart failure causes for readmission and their associated risk factors is necessary to reduce overall readmissions, since the vast majority of readmissions are not for heart failure. Further research is needed to identify and characterize comorbidities and combinations of comorbidities that place patients at greatest risk for adverse outcomes. These findings, in turn, may reveal opportunities to individualize care and guide development of prospective interventions designed to have greater impact on reducing readmissions and improving other clinical outcomes.

Supplementary Material

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Table 2.

Baseline characteristics of patients with a 7-day or 8–30 day readmission and all 30-day readmissions for Heart Failure vs. Non-Heart Failure

7 Days 8–30 Days 30 Days
Heart Failure
Admission
N (%)
(11,652)		 Non-Heart
Failure
Admission
N (%)
(28,394)		 SMD
* 		Heart Failure
Admission
N (%)
(23,798)		 Non-Heart
Failure
Admission
N (%)
(53,279)		 SMD
* 		Heart Failure
Admission
N (%)
(35,450)		 Non-Heart
Failure
Admission
N (%)
(81,673)		 SMD
*
Age Category −0.03 −0.04 −0.04
40–64 years 2,621 (22.5) 5,712 (20.1) 0.06 5,514 (23.2) 11,195 (21) 0.05 8,135 (22.9) 16,907 (20.7) 0.05
65–74 years 2,179 (18.7) 5,625 (19.8) −0.03 4,649 (19.5) 10,853 (20.4) −0.02 6,828 (19.3) 16,478 (20.2) −0.02
75–84 years 3,588 (30.8) 9,200 (32.4) −0.03 7,211 (30.3) 17,114 (32.1) −0.04 10,799 (30.5) 26,314 (32.2) −0.04
≥ 85 years 3,264 (28) 7,857 (27.7) 0.01 6,424 (27) 14,117 (26.5) 0.01 9,688 (27.3) 21,974 (26.9) 0.01
Female 5,625 (48.3) 14,491 (51) −0.06 11,803 (49.6) 27,666 (51.9) −0.05 17,428 (49.2) 42,157 (51.6) −0.05
Race
White 7,447 (63.9) 18,725 (65.9) −0.04 14,764 (62) 35,052 (65.8) −0.08 22,211 (62.7) 53,777 (65.8) −0.07
Black 1,609 (13.8) 3,525 (12.4) 0.04 3,842 (16.1) 6,949 (13) 0.09 5,451 (15.4) 10,474 (12.8) 0.07
Hispanic 1,616 (13.9) 3,743 (13.2) 0.02 3,290 (13.8) 6,980 (13.1) 0.02 4,906 (13.8) 10,723 (13.1) 0.02
Asian/Pacific Islander, Native American, 980 (8.4) 2,401 (8.5) 0.00 1,902 (8) 4,298 (8.1) 0.00 2,882 (8.1) 6,699 (8.2) 0.00
Other, Missing
Acute Secondary Diagnoses Coded on Index Hospitalization
Acute renal failure 2,400 (20.6) 5,388 (19) 0.04 4,445 (18.7) 9,280 (17.4) 0.03 6,845 (19.3) 14,668 (18) 0.03
Cardiac arrest and ventricular fibrillation 665 (5.7) 1,398 (4.9) 0.03 1,244 (5.2) 2,530 (4.7) 0.02 1,909 (5.4) 3,928 (4.8) 0.03
Acute myocardial infarction 697 (6) 1,486 (5.2) 0.03 1,097 (4.6) 2,412 (4.5) 0.00 1,794 (5.1) 3,898 (4.8) 0.01
Pleural effusion 885 (7.6) 2,023 (7.1) 0.02 1,740 (7.3) 3,743 (7) 0.01 2,625 (7.4) 5,766 (7.1) 0.01
Supraventricular tachycardia 4,760 (40.9) 11,420 (40.2) 0.01 9,806 (41.2) 21,764 (40.8) 0.01 14,566 (41.1) 33,184 (40.6) 0.01
Pneumonia 1,576 (13.5) 4,647 (16.4) −0.08 3,196 (13.4) 8,378 (15.7) −0.07 4,772 (13.5) 13,025 (15.9) −0.07
Acute exacerbation of chronic lung disease 1,345 (11.5) 4,438 (15.6) −0.12 2,966 (12.5) 8,125 (15.2) −0.08 4,311 (12.2) 12,563 (15.4) −0.09
Acute Illnesses coded as Primary or any Secondary Dx within 90 days before Index Hospitalization
Acute myocardial infarction 949 (8.1) 1,619 (5.7) 0.10 1,781 (7.5) 3,138 (5.9) 0.06 2,730 (7.7) 4,757 (5.8) 0.07
Conduction disorders 1,116 (9.6) 2,431 (8.6) 0.04 2,298 (9.7) 4,484 (8.4) 0.04 3,414 (9.6) 6,915 (8.5) 0.04
Acute renal failure 1,259 (10.8) 3,032 (10.7) 0.00 2,473 (10.4) 5,656 (10.6) −0.01 3,732 (10.5) 8,688 (10.6) 0.00
Supraventricular tachycardia 1,828 (15.7) 4,544 (16) −0.01 3,733 (15.7) 8,576 (16.1) −0.01 5,561 (15.7) 13,120 (16.1) −0.01
Pneumonia 868 (7.4) 2,354 (8.3) −0.03 1,703 (7.2) 4,466 (8.4) −0.05 2,571 (7.3) 6,820 (8.4) −0.04
Acute exacerbation of chronic lung disease 584 (5) 1,888 (6.6) −0.07 1,373 (5.8) 3,652 (6.9) −0.04 1,957 (5.5) 5,540 (6.8) −0.05
Clinical sepsis 438 (3.8) 1,350 (4.8) −0.05 735 (3.1) 2,367 (4.4) −0.07 1,173 (3.3) 3,717 (4.6) −0.06
Chronic conditions coded at any point within 2 years before or on Index Hospitalization
Chronic valvular heart disease 4,653 (39.9) 10,156 (35.8) 0.09 9,531 (40) 19,784 (37.1) 0.06 14,184 (40) 29,940 (36.7) 0.07
Prior secondary diagnosis of heart failure 4,959 (42.6) 11,253 (39.6) 0.06 10,407 (43.7) 21,759 (40.8) 0.06 15,366 (43.3) 33,012 (40.4) 0.06
Chronic kidney disease 5,666 (48.6) 13,112 (46.2) 0.05 11,337 (47.6) 24,535 (46.1) 0.03 17,003 (48) 37,647 (46.1) 0.04
History of past non-compliance 1,345 (11.5) 3,025 (10.7) 0.03 2,883 (12.1) 5,963 (11.2) 0.03 4,228 (11.9) 8,988 (11) 0.03
Chronic coronary artery disease 7,738 (66.4) 18,609 (65.5) 0.02 15,847 (66.6) 34,834 (65.4) 0.03 23,585 (66.5) 53,443 (65.4) 0.02
Diabetes Mellitus 5,883 (50.5) 14,167 (49.9) 0.01 11,993 (50.4) 26,471 (49.7) 0.01 17,876 (50.4) 40,638 (49.8) 0.01
Chronic complicated hypertension 5,453 (46.8) 12,900 (45.4) 0.03 10,915 (45.9) 24,318 (45.6) 0.00 16,368 (46.2) 37,218 (45.6) 0.01
Pulmonary circulation disease 2,441 (20.9) 6,074 (21.4) −0.01 5,335 (22.4) 11,674 (21.9) 0.01 7,776 (21.9) 17,748 (21.7) 0.01
Chronic disorders of lipoid metabolism 6,629 (56.9) 16,260 (57.3) −0.01 13,587 (57.1) 30,622 (57.5) −0.01 20,216 (57) 46,882 (57.4) −0.01
History of tobacco use 4,051 (34.8) 10,270 (36.2) −0.03 8,575 (36) 19,661 (36.9) −0.02 12,626 (35.6) 29,931 (36.6) −0.02
Chronic peripheral vascular disease 2,213 (19) 5,545 (19.5) −0.01 4,417 (18.6) 10,522 (19.7) −0.03 6,630 (18.7) 16,067 (19.7) −0.02
Hypothyroidism 2,266 (19.4) 5,705 (20.1) −0.02 4,621 (19.4) 11,061 (20.8) −0.03 6,887 (19.4) 16,766 (20.5) −0.03
History of transient ischemic attack 1,266 (10.9) 3,224 (11.4) −0.02 2,456 (10.3) 6,169 (11.6) −0.04 3,722 (10.5) 9,393 (11.5) −0.03
Chronic Essential Hypertension 6,791 (58.3) 17,311 (61) −0.05 14,238 (59.8) 32,674 (61.3) −0.03 21,029 (59.3) 49,985 (61.2) −0.04
Obesity 2,103 (18) 5,611 (19.8) −0.04 4,424 (18.6) 10,685 (20.1) −0.04 6,527 (18.4) 16,296 (20) −0.04
Depression 1,735 (14.9) 4,935 (17.4) −0.07 3,530 (14.8) 9,347 (17.5) −0.07 5,265 (14.9) 14,282 (17.5) −0.07
Chronic electrolyte disorders 6,010 (51.6) 15,374 (54.1) −0.05 11,659 (49) 28,392 (53.3) −0.09 17,669 (49.8) 43,766 (53.6) −0.08
Chronic deficiency anemia 5,560 (47.7) 14,188 (50) −0.05 11,002 (46.2) 27,223 (51.1) −0.10 16,562 (46.7) 41,411 (50.7) −0.08
Chronic weight loss 905 (7.8) 2,751 (9.7) −0.07 1,659 (7) 5,063 (9.5) −0.09 2,564 (7.2) 7,814 (9.6) −0.08
Chronic lung disease 4,933 (42.3) 13,407 (47.2) −0.10 10,256 (43.1) 25,111 (47.1) −0.08 15,189 (42.9) 38,518 (47.2) −0.09
Neurologic Disorders 1,321 (11.3) 4,156 (14.6) −0.10 2,569 (10.8) 7,596 (14.3) −0.10 3,890 (11) 11,752 (14.4) −0.10
Expected Primary Payer
Medicare 8,964 (76.9) 22,670 (79.8) −0.07 18,286 (76.8) 42,329 (79.4) −0.06 27,250 (76.9) 64,999 (79.6) −0.07
Medicaid 1,055 (9.1) 2,173 (7.7) 0.05 2,300 (9.7) 4,215 (7.9) 0.06 3,355 (9.5) 6,388 (7.8) 0.06
Private Insurance 1,051 (9) 2,601 (9.2) 0.00 2,008 (8.4) 4,880 (9.2) −0.03 3,059 (8.6) 7,481 (9.2) −0.02
Self-Pay, No Charge, Other, Missing 582 (5) 950 (3.3) 0.08 1,204 (5.1) 1,855 (3.5) 0.08 1,786 (5) 2,805 (3.4) 0.08
Medicare, age <65 696 (6) 1,919 (6.8) −0.03 1,552 (6.5) 3,691 (6.9) −0.02 2,248 (6.3) 5,610 (6.9) −0.02
Discharge Disposition
Routine Discharge 5,832 (50.1) 13,183 (46.4) 0.07 12,692 (53.3) 26,137 (49.1) 0.09 18,524 (52.3) 39,320 (48.1) 0.08
Transfer to Short-term Hospital 67 (0.6) 175 (0.6) −0.01 136 (0.6) 323 (0.6) 0.00 203 (0.6) 498 (0.6) 0.00
Transfer Other: Includes SNF, 2,336 (20.0) 7,140 (25.2) −0.12 4,512 (19.0) 13,464 (25.3) −0.15 6,848 (19.3) 20,604 (25.2) −0.14
Intermediate Care Facility, Another type of facility
Home Health Care 3,001 (25.8) 7,238 (25.5) 0.01 5,951 (25) 12,641 (23.7) 0.03 8,952 (25.3) 19,879 (24.3) 0.02
Against Medical Advice 408 (3.5) 630 (2.2) 0.08 496 (2.1) 677 (1.3) 0.06 904 (2.6) 1,307 (1.6) 0.07
Discharge Alive, Destination Unknown or Missing 8 (0.1) 28 (0.1) −0.01 11 (0) 37 (0.1) −0.01 19 (0.1) 65 (0.1) −0.01
Length of Stay
LOS Quartile 1 2,742 (23.5) 5,546 (19.5) 0.10 5,133 (21.6) 10,528 (19.8) 0.04 7,875 (22.2) 16,074 (19.7) 0.06
LOS Quartile 2 3,339 (28.7) 7,799 (27.5) 0.03 7,227 (30.4) 15,024 (28.2) 0.05 10,566 (29.8) 22,823 (27.9) 0.04
LOS Quartile 3 2,684 (23) 7,036 (24.8) −0.04 6,043 (25.4) 13,656 (25.6) −0.01 8,727 (24.6) 20,692 (25.3) −0.02
LOS Quartile 4 2,887 (24.8) 8,013 (28.2) −0.08 5,395 (22.7) 14,071 (26.4) −0.09 8,282 (23.4) 22,084 (27) −0.08
LOS in Days, Median (IQR) 4 (3, 7) 5 (3, 8) −0.10 4 (3, 7) 5 (3, 8) −0.11 4 (3,7) 5 (3,8) −0.11
Median (IQ Range) cost of index hospitalization $7,864 (4,660, 14,076) $8,663 (5,223, 15,921) −0.09 $7,683 (4,777, 13,382) $8,395 (5,127, 14,856) −0.10 $7,738 (4,737, 13,575) $8,479 (5,160 15,217) −0.10
Transferred during index presentation 534 (4.6) 1,513 (5.3) −0.03 941 (4) 2,526 (4.7) −0.04 1,475 (4.2) 4,039 (4.9) −0.04
Readmitted to same hospital as index hospitalization 9,231 (79.2) 21,319 (75.1) 0.10 19,194 (80.7) 39,922 (74.9) 0.14 28,425 (80.2) 61,241 (75) 0.12
Index admission through Emergency Department 10,496 (90.1) 25,124 (88.5) 0.05 21,276 (89.4) 46,909 (88) 0.04 31,772 (89.6) 72,033 (88.2) 0.05
Readmission through Emergency Department 10,440 (89.6) 24,657 (86.8) 0.09 20,926 (87.9) 43,834 (82.3) 0.16 31,366 (88.5) 68,491 (83.9) 0.13
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*

Standardized Mean Difference (SMD), where absolute value ≥ 0.10 is considered clinically meaningful.

CLINICAL SIGNIFICANCE.

  • 21.4% of patients hospitalized with heart failure are readmitted within 30 days.

  • Median time to readmission is 12 days.

  • 69.7% of readmissions are for non-heart failure diagnoses, most commonly other cardiovascular conditions, pulmonary disease, and infections.

  • Future interventions to reduce readmissions should focus on common comorbidities that contribute to the readmission burden

Acknowledgments

FUNDING: Washington University Center for Administrative Database Research, Grant Number R24 HS19455

We would like to thank Graham Colditz, MD, DrPH, and the Heart Failure Clinical Research Network for their mentorship and support. We also acknowledge the Washington University Center for Administrative Database Research, grant R24 HS19455 through the Agency for Healthcare Research and Quality. Research reported in this publication was supported by the Washington University Institute of Clinical and Translational Sciences grant UL1 TR000448 from the National Center for Advancing Translational Sciences of the National Institutes of Health (NIH), ICTS ID# JIT286. The content is solely the responsibility of the authors and does not necessarily represent the official view of the NIH.

Footnotes

AUTHOR DISCLOSURES AND CONFLICTS OF INTEREST STATEMENT

No authors have any financial disclosures or conflicts of interest to report. All authors had access to the data and a role in writing the manuscript. All authors approved the final manuscript.

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Supplementary Materials

1
NIHMS859044-supplement-1.pdf (47.1KB, pdf)
2
NIHMS859044-supplement-2.pdf (45.2KB, pdf)
3
NIHMS859044-supplement-3.pdf (67.2KB, pdf)
4-5
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