Measuring patient safety remains an ongoing challenge. This systematic review examined whether preventable death rates could be used as a measure of hospital quality. Researchers reviewed 23 studies and found that estimates of preventable in-hospital death are consistently low. Ascertainment of preventability was not consistent across multiple clinician-reviewers, and the authors estimate that cases would need review by eight or more clinicians to achieve the precision required. The authors conclude that preventable death rates would not be a valid or reliable measure of patient safety. A past PSNet interview discussed the development of hospital standardized mortality ratios and their role in monitoring performance.