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Original Research |

The Association Between Hospital Volume and Processes, Outcomes, and Costs of Care for Congestive Heart Failure

Karen E. Joynt, MD, MPH; E. John Orav, PhD; and Ashish K. Jha, MD, MPH
[+] Article and Author Information

From Harvard School of Public Health, Brigham and Women's Hospital, and Veterans Affairs Boston Health Care System, Boston, Massachusetts.


Acknowledgment: The authors thank Jie Zheng, PhD, from the Department of Health Policy and Management, Harvard School of Public Health, for assistance with statistical programming. Dr. Zheng received compensation as part of regular employment. The authors also thank Peter Lindenauer, MD, MSc, for reviewing an earlier draft of the manuscript.

Grant Support: By an American Heart Association Clinical Research Program grant (10CRP3780037). Dr. Joynt was supported by a National Institutes of Health Training Grant (T32HL007604-24) held by Brigham and Women's Hospital Division of Cardiovascular Medicine.

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M10-1177.

Reproducible Research Statement:Study protocol and statistical code: Available from Dr. Joynt (e-mail, kjoynt@partners.org). Data set: Not available.

Requests for Single Reprints: Karen E. Joynt, MD, MPH, Brigham and Women's Hospital, 75 Francis Street, Boston MA 02115; e-mail, kjoynt@partners.org.

Current Author Addresses: Dr. Joynt: Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115.

Dr. Orav: Brigham and Women's Hospital, Division of General Internal Medicine, 1620 Tremont Street, 3rd Floor, Boston, MA 02115.

Dr. Jha: Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115.

Author Contributions: Conception and design: K.E. Joynt, A.K. Jha.

Analysis and interpretation of the data: K.E. Joynt, E.J. Orav, A.K. Jha.

Drafting of the article: K.E. Joynt, A.K. Jha.

Critical revision of the article for important intellectual content: K.E. Joynt, E.J. Orav, A.K. Jha.

Final approval of the article: K.E. Joynt, A.K. Jha.

Provision of study materials or patients: A.K. Jha.

Statistical expertise: E.J. Orav.

Obtaining of funding: K.E. Joynt, A.K. Jha.

Collection and assembly of data: K.E. Joynt, A.K. Jha.


Ann Intern Med. 2011;154(2):94-102. doi:10.7326/0003-4819-154-2-201101180-00008
Text Size: A A A

Background: Congestive heart failure (CHF) is common and costly, and outcomes remain suboptimal despite pharmacologic and technical advances.

Objective: To examine whether hospitals with more experience in caring for patients with CHF provide better, more efficient care.

Design: Retrospective cohort study.

Setting: 4095 hospitals in the United States.

Patients: Medicare fee-for-service patients with a primary discharge diagnosis of CHF.

Measurements: Hospital Quality Alliance CHF process measures; 30-day, risk-adjusted mortality rates; 30-day, risk-adjusted readmission rates; and costs per discharge. National Medicare claims data from 2006 to 2007 were used to examine the relationship between hospital case volume and quality, outcomes, and costs for patients with CHF.

Results: Hospitals in the low-volume group had lower performance on the process measures (80.2%) than did medium-volume (87.0%) or high-volume (89.1%) hospitals (P < 0.001). In the low-volume group, being admitted to a hospital with a higher case volume was associated with lower mortality, lower readmission, and higher costs. Similar, though smaller, relationships were found between case volume and both mortality and costs in the medium- and high-volume hospital groups.

Limitations: Analysis was limited to Medicare patients 65 years or older. Risk adjustment was performed by using administrative data.

Conclusion: Experience with managing CHF, as measured by an institution's volume, is associated with higher quality of care and better outcomes for patients but a higher cost. Understanding which practices employed by high-volume institutions account for these advantages can help improve quality of care and clinical outcomes for all patients with CHF.

Primary Funding Source: American Heart Association.

Figures

Grahic Jump Location
Figure.
Relationship between CHF volume and processes, outcomes, and costs of care.

CHF = congestive heart failure; HQA = Hospital Quality Alliance.

Grahic Jump Location

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The Larger the Better?
Posted on January 23, 2011
Gen-Min Lin
Hualien-Armed Forces General Hospital, Hualien, Taiwan
Conflict of Interest: None Declared

To the Editor: Dr Joynt and colleagues analyzed Medicare fee-for-service patients with a primary discharge diagnosis of congestive heart failure (CHF) in the United States and found that in the low-volume group, being admitted to a hospital with a higher case volume was associated with lower mortality, lower readmission, and higher costs.1 In their report, patients with CHF receiving intensive cardiac care accounted for 16% in the low-volume hospitals compared to 37% and 69% in the medium-volume and high-volume hospitals respectively. As we know, CHF patients with many comorbidities and severe symptoms will need intensive cardiac care. Therefore, a higher 30-day mortality rate and readmission rate in low-volume group seemed unreasonable. In this regard, we noticed that only 61% of low-volume hospitals in the urban locations. Because patients could be included in the sample more than once, many who may deteriorate heart failure symptoms in the primary small-sized hospitals (73% in the low-volume group) subsequently "discharged" and were transferred to the second medium- or large-sized hospitals (>80% in the medium-and high-volume groups) for intensive cardiac care. However, after the discharges from the second hospitals, patients may die or return to the primary hospitals for recurrent heart failure within 30 days. Obviously, the 30-day mortality rate and readmission rate may be double estimated in the primary low- volume hospitals and the second referral high-volume hospitals in the urban locations. In addition, a small sample size in the denominator in low-volume hospitals may augment the effectors despite 2133 hospitals were collected together. For example, if those receiving intensive cardiac care were the highest risk populations to death, we will obtain 14, 105, and 415 persons in the highest risk per hospital within 23 months in low-volume, medium- volume and high-volume hospitals respectively. By chance, 1-2 patients (7.1-14.3%) may die in low-volume hospitals (11-13% in the paper), 11-12 patients (9.5-11.4%) may die in medium-volume hospitals (10.5-11% in the paper) and 41-45 patients (10.5-10.8%) may die in the large-volume hospitals (10-10.5% in the paper). After risk adjustments, the death rate would be higher in low-volume groups because the change of numerator dramatically affected the results which closely approached to the mean of death rate on standard treatment for patients with heart failure. This controversy was also seen between a cluster of small-sized clinical trials based meta-analysis and a large sample-sized clinical trial.2 In summary, there were too many biases to conclude that the higher risk of 30-day death and readmission rates for heart failure in low-volume hospitals in the United States.

References

1. Joynt KE, Orav EJ, Jha AK. The association between hospital volume and processes, outcomes, and costs of care for congestive heart failure. Ann Intern Med. 2011; 154:94-102.

2. Davey Smith G, Egger M. Meta-analyses of randomised controlled trials. Lancet. 1997; 350:1182.

Conflict of Interest:

None declared

Response to Lin
Posted on February 28, 2011
Karen E. Joynt
Brigham and Women's Hospital, Harvard School of Public Health
Conflict of Interest: None Declared

To the Editor:

Lin brings up a number of points which we appreciate the opportunity to address.

First, the cardiac intensive care numbers that Lin cites (16% for low -volume, 37% for medium-volume, and 69% for high-volume hospitals) are not the proportion of patients that required intensive care, but rather the proportion of hospitals in each category that have a cardiac intensive care unit in their facility. Prior studies suggest that 4-5% of patients hospitalized with heart failure receive intensive care;(1) without this service available on-site, transfer may have been necessary. Lin also suggests that transfers were "double estimated". However, in this study, we were careful to avoid this problem. In the case of transfers, mortality was assigned to the admitting hospital while readmissions were assigned to the discharging hospital, using the convention established by the Centers for Medicare and Medicaid services.(2)

Additionally, Lin suggests that the small sample sizes in our low- volume hospitals would bias our estimates, but again bases calculations on the erroneously assumed distribution of intensive care patients as outlined above. Our sample in the low-volume hospital group was 176,981 patients, with a median of 85 patients at each of these 2,133 hospitals. While we agree that any individual hospital's point estimate for mortality or readmission could vary from year to year based on sample size alone, as a group, these hospitals should still vary around their true average - further, our analyses were carried out at the patient level.

Finally, Lin raises the interesting analogy between examining low- volume centers in a large database analysis and combining small clinical trials in a meta-analysis. While this analogy deserves further consideration, there are important ways in which the challenges are different. The primary issue of small trials is that the population from which each of the trials is sampled may not be representative (due to selection bias or publication bias) - and combining many non- representative trials into a meta-analysis does not improve the representativeness of the final product.(3) We do not feel that this issue applies here. Our study included all Medicare patients with heart failure over 23-months discharged from U.S. hospitals with at least 25 discharges during the study period, and should thus be generalizable, at least to Medicare patients within the U.S. Further, our findings are in line with numerous prior studies demonstrating associations between volume and outcomes for other conditions,(4, 5) which should give the reader additional reassurance that these findings are valid..

Karen E. Joynt, MD MPH E. John Orav, PhD Ashish K. Jha, MD MPH

References:

1. Singer AJ, Birkhahn RH, Guss D, et al. Rapid Emergency Department Heart Failure Outpatients Trial (REDHOT II): a randomized controlled trial of the effect of serial B-type natriuretic peptide testing on patient management. Circ Heart Fail. 2009;2(4):287-93.

2. Desai MM, Lin Z, Schreiner GC, et al. (Yale-New Haven Health Services Corporation / Center for Outcomes Research and Evaluation (YNHHSC/CORE)). 2009 Measures Maintenance Technical Report: Acute Myocardial Infarction, Heart Failure, and Pneumonia 30-Day Risk Standardized Readmission Measures. 2009.

3. LeLorier J, Gregoire G, Benhaddad A, Lapierre J, Derderian F. Discrepancies between meta-analyses and subsequent large randomized, controlled trials. N Engl J Med. 1997;337(8):536-42.

4. Birkmeyer JD, Siewers AE, Finlayson EV, et al. Hospital volume and surgical mortality in the United States. N Engl J Med. 2002;346(15):1128- 37.

5. Ross JS, Normand SL, Wang Y, et al. Hospital volume and 30-day mortality for three common medical conditions. N Engl J Med. 2010;362(12):1110-8.

Conflict of Interest:

None declared

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