Where Is the Value in Ambulatory Versus Inpatient Surgery?

David F. Friedlander, MD, MPH; Marieke J. Krimphove, MD; Alexander P. Cole, MD; Maya Marchese, MS; Stuart R. Lipsitz, ScD; Joel S. Weissman, PhD; Andrew J. Schoenfeld, MD, MSc; Gezzer Ortega, MD, MPH; Quoc-Dien Trinh, MD


Annals of Surgery. 2021;273(5):909-916. 

In This Article

Abstract and Introduction


Objective: The aim of this study was to estimate the effect of index surgical care setting on perioperative costs and readmission rates across 4 common elective general surgery procedures.

Summary Background Data: Facility fees seem to be a driving force behind rising US healthcare costs, and inpatient-based fees are significantly higher than those associated with ambulatory services. Little is known about factors influencing where patients undergo elective surgery.

Methods: All-payer claims data from the 2014 New York and Florida Healthcare Cost and Utilization Project were used to identify 73,724 individuals undergoing an index hernia repair, primary total or partial thyroidectomy, laparoscopic cholecystectomy, or laparoscopic appendectomy in either the inpatient or ambulatory care setting. Inverse probability of treatment weighting-adjusted gamma generalized linear and logistic regression was employed to compare costs and 30-day readmission between inpatient and ambulatory-based surgery, respectively.

Results: Approximately 87% of index surgical cases were performed in the ambulatory setting. Adjusted mean index surgical costs were significantly lower among ambulatory versus inpatient cases for all 4 procedures (P < 0.001 for all). Adjusted odds of experiencing a 30-day readmission after thyroidectomy [odds ratio (OR) 0.70, 95% confidence interval (CI), 0.53–0.93; P = 0.03], hernia repair (OR 0.28, 95% CI, 0.20–0.40; P < 0.001), and laparoscopic cholecystectomy (OR 0.37, 95% CI, 0.32–0.43; P < 0.001) were lower in the ambulatory versus inpatient setting. Readmission rates among ambulatory versus inpatient-based laparoscopic appendectomy were comparable (OR 0.63, 95% CI, 0.31–1.26; P = 0.19).

Conclusions: Ambulatory surgery offers significant costs savings and generally superior 30-day outcomes relative to inpatient-based care for appropriately selected patients across 4 common elective general surgery procedures.


Recent value-based purchasing efforts seek to contain US healthcare expenditures by curtailing inefficient or "low-value" practices.[1] Significant value can be realized through improved efficiency in surgical care pathways due to the cost-intensive nature of these events.[2] Directing appropriate surgical candidates to ambulatory (aka outpatient) rather than inpatient facilities has emerged as one such value proposition as facility costs seem to be contributing to increases in US health spending, and ambulatory costs are significantly lower than those produced by the inpatient setting.[3,4] For example, several contemporary case series and retrospective cohort studies utilizing claims data support the feasibility of ambulatory cholecystectomy[5,6] and appendectomy,[7,8] which represent the 6th and 11th most frequently performed inpatient-based procedures within the United States, respectively.[9]

However, in order for these cost efficiencies to be realized, perioperative outcomes must be comparable between the ambulatory and inpatient care settings. Outside of the orthopedic literature, few studies have simultaneously compared costs and outcomes associated with inpatient versus ambulatory-based surgical care.[10] Despite this dearth of cost-effectiveness data, spending on ambulatory surgery has risen dramatically in recent years, approaching 30% of Medicare surgical payments in 2014.[11] Consequently, it is imperative that payers and policymakers alike gain further insights into additional value afforded by ambulatory, rather than inpatient, surgical care. In this context, we used all-payer claims data from Florida and New York to estimate the effect of index surgical care setting on 30-day costs and readmission rates across 4 common general surgery procedures amendable to ambulatory surgery. Our guiding hypothesis is that ambulatory-based surgical care is associated with lower risk-adjusted 30-day costs and comparable outcomes relative to similar surgeries performed in the inpatient setting.