Hinton ZW, Fletcher AN, Ryan SP, et al. - Body mass index (BMI), American Society of Anesthesiologists (ASA) score, and Elixhauser Comorbidity Index (ECI) are measures that are applied to prognosticate perioperative outcomes, though little is known about their comparative predictive impacts. Researchers examined these indices on costs, operating room (OR) time, and length of stay (LOS) with the hypothesis that they would have a differential influence on each outcome variable. Between 2015 and 2018, a retrospective review of the institutional database was completed on primary TKA patients. Researchers constructed univariable and multivariable models to analyze the strength of BMI, ASA, and Elixhauser comorbidities for predicting changes to total hospital and surgical costs, OR time and LOS. A total of 1,313 patients were recruited for the study. There are important variations in their predictive nature, though ASA, BMI, and elixhauser comorbidities have the potential to impact outcomes and cost. The data indicated that other measures like Elixhauser and ASA score were more indicative of cost outside of the OR and LOS, while BMI is independently predictive of intraoperative resource utilization. These findings indicate the differing effect of BMI, ASA, and patient comorbidities in impacting cost and time consumption throughout perioperative care.