19. Risk factors causing unexpected conversion from ambulatory to inpatient admission among 1- or 2-level ACDF patients

BACKGROUND CONTEXT In an era of rising health care costs and pressure to improve patient satisfaction, surgeries are increasingly performed in an ambulatory setting. One example is anterior cervical discectomy and fusion (ACDF), which is one of the most common cervical spine surgeries. However, there are certain patients who are unexpectedly converted from outpatient to inpatient and little is known about the risk factors for conversion. PURPOSE The aim of this study was to investigate the factors associated with the conversion of patient status from ambulatory to inpatient in ACDF. STUDY DESIGN/SETTING A retrospective observational study PATIENT SAMPLE Patients who underwent 1- or 2-level ACDF in an ambulatory setting at a single specialized orthopedic hospital between February 2016 to December 2021. OUTCOME MEASURES Length of stay, conversion rates from ambulatory setting to inpatient. METHODS Patients were divided into two groups based on length of stay: 1) Ambulatory (Discharge within 24 hours) or Extended stay (fewer than 48 hours), and 2) Inpatient (greater than 48 hours). Baseline patient demographic data, surgical information, complications, and conversion reasons were compared between the two groups. Multivariate analysis was conducted to consider independent risk factors for conversion to inpatient. RESULTS In total 662 patients underwent 1- or 2-level ACDF (median age, 52 years; 59.5% were male), with 494 (74.6%) patients discharged within 48 hours and 168 (25.4%) patients converted to inpatient. Multivariable logistic analysis demonstrated that female patients (OR, 2.89; 95% CI 1.80 to 4.63; p < 0.001), lower body mass index <25 (OR, 2.56; 95% CI 1.55 to 4.24; p < 0.001), American Society of Anesthesiologists classification (ASA) =3 (OR, 2.55; 95% CI 1.21 to 5.39; p = 0.014), current smoker (OR, 0.16; 95% CI 0.05 to 0.50; p = 0.001), long operation (OR, 1.01; 95% CI 1.01 to 1.01; p = 0.009), high estimated blood loss (OR, 1.01; 95% CI 1.00 to 1.02; p = 0.002), upper-level surgery (OR, 1.66; 95% CI 1.01 to 2.74; p = 0.045), 2-level fusion (OR, 2.05; 95% CI 1.28 to 3.28; p = 0.003), late operation start time (OR, 1.99; 95% CI 1.18 to 2.93; p = 0.008), and high postoperative pain score (OR, 1.31; 95% CI 1.16 to 1.47; p < 0.001) 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. Airway management was significantly associated with higher ASA status, receiving oral anticoagulation therapy, medical history of hypertension, and obstructive sleep apnea syndrome of the patient. CONCLUSIONS Our study demonstrates that there are several independent risk factors for prolonged hospital stay after ambulatory ACDF surgery. Some factors are unmodifiable, such as female sex, or relatively unmodifiable, such as low BMI and high ASA grade. However, other factors present good targets for intervention. Procedure duration and blood loss should be closely monitored and optimized. Patients indicated for same-day ACDF surgery should not be performed late in the operating schedule. Pain regimens should be evaluated and updated to provide adequate pain control. Lastly, certain patients may require reintubation or prolonged airway management – this is a small subset of patients, but surgeons should be vigilant for this potentially life-threatening complication. Focusing on modifiable factors might reduce the conversion rate from ambulatory to inpatient, benefitting both patients and facilities. FDA Device/Drug Status This abstract does not discuss or include any applicable devices or drugs. In an era of rising health care costs and pressure to improve patient satisfaction, surgeries are increasingly performed in an ambulatory setting. One example is anterior cervical discectomy and fusion (ACDF), which is one of the most common cervical spine surgeries. However, there are certain patients who are unexpectedly converted from outpatient to inpatient and little is known about the risk factors for conversion. The aim of this study was to investigate the factors associated with the conversion of patient status from ambulatory to inpatient in ACDF. A retrospective observational study Patients who underwent 1- or 2-level ACDF in an ambulatory setting at a single specialized orthopedic hospital between February 2016 to December 2021. Length of stay, conversion rates from ambulatory setting to inpatient. Patients were divided into two groups based on length of stay: 1) Ambulatory (Discharge within 24 hours) or Extended stay (fewer than 48 hours), and 2) Inpatient (greater than 48 hours). Baseline patient demographic data, surgical information, complications, and conversion reasons were compared between the two groups. Multivariate analysis was conducted to consider independent risk factors for conversion to inpatient. In total 662 patients underwent 1- or 2-level ACDF (median age, 52 years; 59.5% were male), with 494 (74.6%) patients discharged within 48 hours and 168 (25.4%) patients converted to inpatient. Multivariable logistic analysis demonstrated that female patients (OR, 2.89; 95% CI 1.80 to 4.63; p < 0.001), lower body mass index <25 (OR, 2.56; 95% CI 1.55 to 4.24; p < 0.001), American Society of Anesthesiologists classification (ASA) =3 (OR, 2.55; 95% CI 1.21 to 5.39; p = 0.014), current smoker (OR, 0.16; 95% CI 0.05 to 0.50; p = 0.001), long operation (OR, 1.01; 95% CI 1.01 to 1.01; p = 0.009), high estimated blood loss (OR, 1.01; 95% CI 1.00 to 1.02; p = 0.002), upper-level surgery (OR, 1.66; 95% CI 1.01 to 2.74; p = 0.045), 2-level fusion (OR, 2.05; 95% CI 1.28 to 3.28; p = 0.003), late operation start time (OR, 1.99; 95% CI 1.18 to 2.93; p = 0.008), and high postoperative pain score (OR, 1.31; 95% CI 1.16 to 1.47; p < 0.001) 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. Airway management was significantly associated with higher ASA status, receiving oral anticoagulation therapy, medical history of hypertension, and obstructive sleep apnea syndrome of the patient. Our study demonstrates that there are several independent risk factors for prolonged hospital stay after ambulatory ACDF surgery. Some factors are unmodifiable, such as female sex, or relatively unmodifiable, such as low BMI and high ASA grade. However, other factors present good targets for intervention. Procedure duration and blood loss should be closely monitored and optimized. Patients indicated for same-day ACDF surgery should not be performed late in the operating schedule. Pain regimens should be evaluated and updated to provide adequate pain control. Lastly, certain patients may require reintubation or prolonged airway management – this is a small subset of patients, but surgeons should be vigilant for this potentially life-threatening complication. Focusing on modifiable factors might reduce the conversion rate from ambulatory to inpatient, benefitting both patients and facilities.