Does size matter? The impact of caseload and expertise concentration on AMI 30-day mortality-A comparison across 10...

To examine the variability of hospital performance within and across countries, using 30-day acute myocardial infarction (AMI) mortality, and to study the impact of hospital characteristics on performance.

Hospital-level adjusted risk standardized mortality rates (RSMR) and hospital characteristics were collected from 10 OECD and two collaborating countries including 1,163 hospitals.

Associations between RSMR and hospital characteristics were studied using univariate and multivariate linear regressions. Clusters of hospitals were created using hierarchical clustering and mortality compared using linear regression.

Wide variation between countries was found for RSMR and hospital characteristics. Regression models showed large country effects. A high volume of AMI admission was associated with lower RSMR in a model using a restricted number of hospital characteristics (-0.83, p < 0.001) but not in a model using all characteristics (-1.03, p = 0.06). Analysis within countries supported this association. Hospital clusters showed clear differences in characteristic distributions but no difference in RSMR.

The effect of volume may support policies toward a concentration of services within the hospital sector. The effect of other hospital characteristics was inconclusive and suggests the importance of system-wide characteristics or pathways of care (i.e. timeliness and nature of initial response and during transportation to a hospital, transfers between hospitals, post-discharge organization) in explaining variation.