Is Annual Preoperative Utilization an Indicator of Postoperative Surgical Outcomes? A Study in Medicare Expenditure

INTRODUCTION: Data on the association of high preoperative healthcare utilization and adverse clinical outcomes are scarce. We sought to evaluate the role of annual preoperative expenditure (APE) as a surrogate for latent variables of risk for adverse short-term postoperative outcomes. METHODS: Low and super-utilizers who underwent abdominal aortic aneurysm repair, coronary artery bypass graft, colectomy, total hip arthroplasty, total knee arthroplasty, or lung resection between 2013 and 2015 were identified from 100% Medicare Inpatient Standard Analytic Files. To assess the association between APE and postoperative outcomes, multivariable logistic regression was utilized. RESULTS: Among 1,049,160 patients, 788,488 (75.1%) and 21,700 (2.1%) patients were preoperative low- and super-utilizers, respectively. Median APE was more than 60 times higher among super-utilizers than low-utilizers ($57,160 vs. $932), as was the cost of the surgical episode ($21,141 vs. $13,179). The predictive ability of APE ranged from 0.683 (95% CI 0.678-0.687) for 90-day readmission to 0.882 (95% CI 0.879-0.886) for a complication at the index hospitalization. Among super-utilizers, the odds of a complication during the surgical episode was nearly double versus low-utilizers (OR = 1.96, 95% CI 1.89-2.04). Super-utilizers also had an increased odds of 30-day readmission (OR = 1.64, 95% CI 1.58-1.69) and mortality (OR = 2.22; 95% CI 2.04-2.42). CONCLUSION: APE was able to predict adverse postsurgical outcomes including complications during the surgical episode, readmission, and 90-day mortality. APE should be considered in the assessment of patient populations when defining risk of adverse postoperative events.