The critical limitations of volume-outcome analysis

There is a justified assumption that the patient outcome is in large part determined by the quality of the care they receive. For certain procedures outside of the field of urology, it has been demonstrated that higher surgical volume, either at the hospital or surgeon level is a proxy for higher quality of care. Multiple studies have followed this line of inquiry and attempted to show that volume may also predict outcome for certain urologic procedures. Review of the published studies shows that the association appears quite weak. However, the real weakness of this line of study is not so much in the findings, but in the universally used and critically flawed study methodology. This article demonstrates how a simple study design flaw has proved to be the Achilles heal of this entire line of research.