Cardiac Enzyme Availability and Hospital Length of Stay

In this issue of Clinical Chemistry , Wu and Clive report an association between hospital length of stay (LOS) and the potential availability of CK-MB results (i.e., anticipated turnaround times, given the institutional approach to measurement) at acute-care hospitals in Massachusetts (1). They report a 0.7-day reduction in mean hospital LOS for those patients with an acute myocardial infarction (AMI) and complication(s) who were managed at hospitals performing CK-MB tests more than once or twice per day. They comment that if this reduction in LOS is real, the small increase in institutional cost to provide more-rapid enzyme results would be more than offset by savings related to the shorter hospital LOS.To put this study into context, one must address several issues: What methodological issues might bias these study results? How are LOS values shortened by the more rapid turnaround times for cardiac enzymes? And why weren’t shorter LOSs seen in other DRG categories?What methodological issues might bias this study ? This retrospective observational study design used a claims-based database. Such a billing database may insufficiently permit patient risk stratification for hospital LOS. For example, from such a database alone, we know nothing of patients’ socioeconomic status and little about their underlying health status. Both factors may significantly affect clinical disposition decisions. Further, the analysis performed did not address the impact of other factors such as infarct location or procedural interventions (e.g., angioplasty or thrombolysis) on hospital LOS.There also is significant potential for selection bias …