Complications, adverse events, and iatrogenesis: classifications and quality of care measurement issues

Accountability in the healthcare system demands the development of valid and reliable measures of quality, particularly outcome measures that have been risk-adjusted for factors that increase the probability of a poor outcome. Although the literature documents the existence of complications, adverse events, and iatrogenic illness, these concepts have not been compared and discussed thoroughly. This article ponders complications as a measure of quality of care by proposing a three-level classification scheme and by examining the incidence, consequence, and determinants of these events.