Risk Factors for Ambulatory Surgery Conversion to Extended Stay Among Patients Undergoing One- or Two-Level Posterior Lumbar Decompression.

STUDY DESIGN: A retrospective observational study.

OBJECTIVE: To investigate the factors associated with the conversion of patient status from Ambulatory surgery (AMS) to observation service (OS) (fewer than 48 hours) or Inpatient (greater than 48 hours).

SUMMARY OF BACKGROUND DATA: AMS is becoming increasingly common in the U.S. because it is associated with a similar quality of care compared to inpatient surgery, significant costs reduction, and patients' desire to recuperate at home. However, there are instances when AMS patients may be subjected to extended hospital stays. Unanticipated extension of hospitalization stays can be a great burden not only to patients, but to medical providers and insurance companies alike.

METHODS: Data from 1,096 patients underwent one- or two-level lumbar decompression AMS at an in-hospital, outpatient surgical facility between January 1, 2019 to March 16, 2020 were collected. Patients were categorized in three groups based on length of stay: 1) AMS, 2) OS, or 3) Inpatient. Demographics, comorbidities, surgical information, and administrative information were collected. Simple and multivariable logistic regression analyses were conducted comparing AMS patients and OS/Inpatient as well as OS and Inpatients.

RESULTS: Of the 1,096 patients, 641 (58%) patients were converted to either OS (n=486) or Inpatient (n=155). The multivariable analysis demonstrated that age (>80 y old), high ASA grade, history of sleep apnea, drain use, high estimated blood loss, long operation, late operation start time, and a high pain score were considered independent risk factors for AMS conversion to OS/Inpatient. The risk factors for OS conversion to Inpatient were an ASA Class 3 or higher, CAD, DM, hypothyroidism, steroid use, drain use, dural tear, and laminectomy.

CONCLUSIONS: Several surgical factors along with patient specific factors were significantly associated with AMS conversion. Addressing modifiable surgical factors might reduce the AMS conversion rate and be beneficial to patients and facilities.