Abstract Conventional wisdom suggests that those who assess healthcare processes and outcomes always should stratify cases by severity of illness; however, infection control personnel should analyze each quality assessment tool with and without severity adjustment and determine whether such adjustment is necessary. This article briefly reviews severity adjustments for diseases or procedures involving specific organ systems, as well as those applicable to all diseases, including the commercially available systems. Also discussed is whether and how these various systems for severity adjustment can be compared. Finally, the article will provide selected references for individuals who will use these scoring systems and need more information.