Risk Factors for Unexpected Conversion from Ambulatory to Inpatient Admission Among One- or Two-level ACDF Patients

A retrospective observational study.The aim of this study was to investigate the factors associated with the conversion of patient status from ambulatory anterior cervical discectomy and fusion (ACDF) to inpatient.Surgeries are increasingly performed in an ambulatory setting in an era of rising healthcare costs and pressure to improve patient satisfaction. ACDF is a common ambulatory cervical spine surgery, however, there are certain patients who are unexpectedly converted from an outpatient procedure to inpatient admission and little is known about the risk factors for conversion.Patients who underwent one-level or two-level ACDF in an ambulatory setting at a single specialized orthopedic hospital between February 2016 to December 2021 were included. Baseline demographics, surgical information, complications, and conversion reasons were compared between patients with ambulatory surgery or observational stay (stay <48 h) and inpatient (stay >48 h).In total, 662 patients underwent one-level or two-level ACDF (median age, 52 yr; 59.5% were male), 494 (74.6%) patients were discharged within 48 hours and 168 (25.4%) patients converted to inpatient. Multivariable logistic regression analysis demonstrated that females, low body mass index <25, American Society of Anesthesiologists classification (ASA) ≥3, long operation, high estimated blood loss, upper-level surgery, two-level fusion, late operation start time, and high postoperative pain score were considered independent risk factors for conversion to inpatient. Pain management was the most common reason for the conversion (80.0%). Ten patients (1.5%) needed reintubation or remained intubated for airway management.Several independent risk factors for prolonged hospital stay after ambulatory ACDF surgery were identified. Although some factors are unmodifiable, other factors, such as procedure duration, operation start time, and blood loss could be potential targets for intervention. Surgeons should be aware of the potential for life-threatening airway complications in ambulatory-scheduled ACDF.