In the American Journal of Surgery, Caroline Reinke and colleagues, including Rachel Kelz, share their findings on state-level variation in wage-adjusted total cost (WATC) of a common surgical procedure. Using data from the Nationwide Inpatient Sample, the researchers performed a retrospective cohort study of patients undergoing a total thyroidectomy. WATC was calculated from charges and adjusted for the area wage index. The authors find that 37% of WATC variance is due to differences across hospitals, 28% is explained by patient-level factors and 8% is due to differences across states. More than a quarter of the variation in cost is not explained by patient-, hospital- or state-level factors. The authors conclude that further research is needed to understand the unexplained variation.