Variability in the American Society of Anesthesiologists Physical Status Classification Scale

Abstract

The American Society of Anesthesiologists (ASA) Physical Status (PS) Classification is used worldwide by anesthesia providers as an assessment of the preoperative physical health of patients. This score also has been used in policy-making, performance evaluation, resource allocation, and reimbursement of anesthesia services and frequently is cited in clinical research. The purpose of this study was to assess interrater reliability and describe sources of variability among anesthesia providers in assigning ASA PS scores. A questionnaire with 10 hypothetical patients scenarios was given to 70 anesthesia providers who were asked to assign ASA PS scores in each scenario and to provide rationale for their decisions. The data were summarized and stratified according to nurse anesthetist or anesthesiologist and military or nonmilitary anesthesia providers. We hypothesized there would be no difference between any of the anesthesia provider groups in assignment of ASA PS scores. A lack of interrater reliability in assigning ASA PS scores was demonstrated. There were no significant differences between the anesthesia provider groups. There was no correlation between ASA PS scoring and years practicing or any of the other demographic variables. Several sources of variability were identified: smoking, pregnancy, nature of the surgery, potential difficult airway, and acute injury.