Propensity Scored Analysis of Outpatient Anterior Lumbar Interbody Fusion: No Increased Complications

Abstract

Study design: Retrospective cohort study.

Objective: The aim were to (1) evaluate differences in postoperative outcomes and cost associated with outpatient anterior lumbar interbody fusion (ALIF) compared with inpatient ALIF, and to (2) identify independent factors contributing to complications after outpatient ALIF.

Summary of background: While lumbar fusion is traditionally performed inpatient, outpatient spinal surgery is becoming more commonplace as surgical techniques improve.

Methods: The study population included all patients below 85 years of age who underwent elective ALIF (CPT-22558). Patients were then divided into those who underwent single-level fusion and multilevel fusion using the corresponding additional level fusion codes (CPT-22585). These resulting populations were then split into outpatient and inpatient cohorts by using a service location modifier. To account for selection bias, propensity score matching was performed; the inpatient cohorts were matched with respect to the outpatient cohorts based on age, sex, and Charlson Comorbidity Index. Statistical significance was set at P<0.05 and the Bonferroni correction was used for each multiple comparison (P<0.004).

Results: Patients undergoing outpatient procedure had decreased rates of medical complications following both single-level and multilevel ALIF. In addition, age above 60, female sex, Charlson Comorbidity Index>3, chronic obstructive pulmonary disease, diabetes mellitus, coronary artery disease, hypertension, and tobacco use were all identified as independent risk factors for increased complications. Finally, the cost of outpatient ALIF was $12,013 while the cost of inpatient ALIF was $27,271 (P<0.001).

Conclusion: The findings add to the growing body of literature advocating for the utilization of ALIF in the outpatient setting for a properly selected group of patients.

Level of evidence: Level IV.