Swan-Ganz catheter use and mortality of myocardial infarction patients.

Using the 1989 Medicare provider analysis and review (MEDPAR) file, we calculated a 30-day indirectly standardized mortality ratio (SMR) for all "fresh" acute myocardial infarction (AMI) Medicare aged cases (i.e., fresh AMI patients are those who had not reported an AMI in the prior 8 weeks) at 2,900 hospitals, as well as an indirectly standardized procedure ratio (SPR) of Swan-Ganz catheter (SGC) use for these AMI cases at each hospital. Cases at hospitals with higher SGC SPRs also had higher SMRs. This positive association persisted when hospitals were further stratified by their annual volume of fresh AMI cases. We believe that our use of cases as the unit of observation, stratified by the SGC SPR of their hospital, avoids some case selection bias in observational studies directly comparing risk-adjusted mortality of cases with and without SGC.