Intensive Care Units With Low Versus High Volume of Myocardial Infarction: Clinical Outcomes, Resource Utilization, and Quality Metrics

Abstract

BackgroundThe volume-outcome relationship associated with intensive care unit (ICU) experience with managing acute myocardial infarction (AMI) remains inadequately understood.Methods and ResultsWithin a multicenter clinical ICU database, we identified patients with a primary ICU admission diagnosis of AMI between 2008 and 2010 to evaluate whether annual AMI volume of an individual ICU is associated with mortality, length-of-stay, or quality indicators. Patients were categorized into those treated in ICUs with low-annual-AMI volume (≤50th percentile, <2 AMI patients/month, n=569 patients) versus high-annual-AMI volume (≥90th percentile, ≥8 AMI patients/month, n=17 553 patients). Poisson regression and generalized estimating equation with negative binomial regression were used to calculate the relative risk (95% CI) for mortality and length-of-stay, respectively, associated with admission to a low-AMI-volume ICU. When compared with high-AMI-volume, patients admitted to low-AMI-volume ICUs had substantially more medical comorbidities, higher in-hospital mortality (11% versus 4%, P<0.001), longer hospitalizations (6.9±7.0 versus 5.0±5.0 days, P<0.001), and fewer evidence-based therapies for AMI (reperfusion therapy, antiplatelets, β-blockers, and statins). However, after adjustment for baseline patient characteristics, low-AMI-volume ICU was no longer an independent predictor of in-hospital mortality (relative risk 1.17 [0.87 to 1.56]) or hospital length-of-stay (relative risk 1.01 [0.94 to 1.08]). Similar findings were noted in secondary analyses of ICU mortality and ICU length-of-stay.ConclusionsAdmission to an ICU with lower annual AMI volume is associated with higher in-hospital mortality, longer hospitalization, and lower use of evidence-based therapies for AMI. However, the relationship between low-AMI-volume and outcomes is no longer present after accounting for the higher-risk medical comorbidities and clinical characteristics of patients admitted to these ICUs.

ICU Use and Quality of Care for Patients With Myocardial Infarction and Heart Failure

“…Lower volume of AMI or HF admissions has previously been associated with worse outcomes, 28,29 and hospitals that used the ICU frequently in the present study tended to have lower annual AMI or HF volume, perhaps utilizing the ICU due to a lack of familiarity in caring for such patients. Furthermore, increased ICU bed availability has been associated with higher ICU admission rates.…”

“…The present study focused on an older population and evaluated associations between ICU admission rates and quality measures. Stolker et al 28 showed that ICUs with low annual AMI volume had higher mortality and provided less evidence-based therapies. Our study looked at a hospital's ICU admission rate and found that hospitals with the highest ICU admission rates had the lowest annual AMI volume.…”

Intensive Care Unit Utilization and Mortality Among Medicare Patients Hospitalized With Non–ST-Segment Elevation Myocardial Infarction

“…Though a relationship between volume and outcome has been demonstrated in many conditions, a recent study failed to identify a relationship between ICU MI volume and outcomes. 20 A more selective ICU utilization strategy may be preferable for cost reasons; however, some initially stable patients will ultimately require ICU care, and no risk model has been developed to identify these patients prior to clinical deterioration.…”

A Long-Forgotten Tale: The Management of Cardiogenic Shock in Acute Myocardial Infarction

“…A comparative study between centers with a low volume versus a high volume of annually treated AMI cases reported significantly lower mortality rates when patients were referred to a high-volume center (11% vs. 4%, p <0.0001 for in-hospital mortality and 7% vs. 3%, p <0.0001 for intensive care unit mortality). 41 These observations are also valid in the case of CS, the most critical condition recorded in a cardiac critical care unit. A statistically significant decrease in overall adjusted mortality was seen in hospitals with high numbers of CS cases.…”