Hospital Volume and Outcomes in Patients Admitted With Heart Failure
What is the relationship between admission volume, process-of-care metrics, and short- and long-term outcomes in patients admitted with acute heart failure (HF)?
The final study cohort was comprised of 125,595 HF patients enrolled in the Get With The Guidelines-HF registry with linked Medicare inpatient data at 342 hospitals. The authors assessed volume both as a continuous variable, and quartiles based on the admitting hospital annual HF case volume, as well: 5-38 (quartile 1), 39-77 (quartile 2), 78-122 (quartile 3), 123-457 (quartile 4). The primary process measures (among candidates for therapy) were assessed at a patient level based on the index hospitalization and included: (1) HF achievement measures, including prescription of angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers; (2) HF quality measures, including prescription of an aldosterone antagonist and cardiac resynchronization therapy (defibrillator-pacemaker or pacemaker only) placed/prescribed; (3) HF reporting measures, including any beta-blocker, implantable cardioverter-defibrillator placed/prescribed; and finally (4) a composite HF defect-free measure, a composite of appropriate discharge instructions, measurement of left ventricular function, prescription of angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers, and prescription of beta-blockers. The primary outcome measures assessed at a patient level included: (1) in-hospital mortality and length of stay, (2) 30-day all-cause mortality and readmissions, and (3) 6-month all-cause mortality and readmissions. The authors utilized adjusted logistic and Cox proportional hazards models to study these associations with hospital volume.
The study authors found that patients admitted to high-volume hospitals had a higher burden of comorbidities. On multivariable modeling, lower-volume hospitals were significantly less likely to be adherent to HF process measures than higher-volume hospitals. Higher hospital volume was not associated with a difference in in-hospital (odds ratio, 0.99; 95% confidence interval [CI], 0.94–1.05; p = 0.78) or 30-day mortality (hazard ratio, 0.99; 95% CI, 0.97–1.01; p = 0.26), or 30-day readmissions (hazard ratio, 0.99; 95% CI, 0.97–1.00; p = 0.10). There was a weak association of higher volumes with lower 6-month mortality (hazard ratio, 0.98; 95% CI, 0.97–0.99; p = 0.001) and lower 6-month all-cause readmissions (hazard ratio, 0.98; 95%, CI 0.97–1.00; p = 0.025).
The study authors concluded that analysis of a large contemporary prospective national quality improvement registry of older patients with HF indicates that hospital volume as a structural metric correlates with process measures, but not with 30-day outcomes, and only marginally with outcomes up to 6 months of follow-up. Hospital profiling should focus on participation in systems of care, adherence to process metrics, and risk standardized outcomes rather than on hospital volume itself.
This is an important article because it suggests that high hospital volumes, by themselves, do not improve outcomes. As the authors point out, hospital administrators will need to allocate resources on other measures of care. The challenge is that the natural history of HF continues to evolve with more and more patients having HF with preserved ejection fraction and having multiple comorbidities such as renal failure and sleep apnea.
Keywords: Adrenergic beta-Antagonists, Angiotensin Receptor Antagonists, Angiotensin-Converting Enzyme Inhibitors, Cardiac Resynchronization Therapy, Comorbidity, Defibrillators, Implantable, Geriatrics, Heart Failure, Hospital Mortality, Hospitals, High-Volume, Hospitals, Low-Volume, Inpatients, Length of Stay, Outcome Assessment (Health Care), Outcome and Process Assessment (Health Care), Quality Improvement, Quality of Health Care, Stroke Volume, Ventricular Function, Left
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