On the Hospital Volume and Outcome Relationship: Does Specialization Matter More Than Volume?

OBJECTIVE: To evaluate the relationship between hospital volume and outcome by focusing on alternative measures of volume that capture specialization and overall throughput of hospitals. DATA SOURCES/STUDY
SETTING: Hospital administrative data from the state of Victoria, Australia; data contain 1,798,474 admitted episodes reported by 135 public and private acute-care hospitals. STUDY
DESIGN: This study contrasts the volume-outcome relationship using regression models with different measures of volume; two-step and single-step risk-adjustment methods are used. DATA COLLECTION/EXTRACTION
METHODS: The sample is restricted to ischemic heart disease (IHD) patients (ICD-10 codes: I20-I25) admitted during 2001/02 to 2004/05. PRINCIPAL
FINDINGS: Overall hospital throughput and degree of specialization display more substantive implications for the volume-outcome relationship than conventional caseload volume measure. Two-step estimation when corrected for heteroscedasticity produces comparable results to single-step methods.
CONCLUSIONS: Different measures of volume could lead to vastly different conclusions about the volume-outcome relationship. Hospital specialization and throughput should both be included as measures of volume to capture the notion of size, focus, and possible congestion effects. © Health Research and Educational Trust.