American Society of Anesthesiologists Physical Status Classification System

"The purpose of the grading system is simply to assess the degree of a patient’s 'sickness' or 'physical state' prior to selecting the anesthetic or prior to performing surgery. Describing patients’ preoperative physical status is used for recordkeeping, for communicating between colleagues, and to create a uniform system for statistical analysis. The grading system is not intended for use as a measure to predict operative risk."