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Featured Articles: Original Clinical Research Report

Outcomes of Sleep Apnea Surgery in Outpatient and Inpatient Settings

Rosero, Eric B. MD, MSc; Joshi, Girish P. MBBS, MD, FFARCSI

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doi: 10.1213/ANE.0000000000005394
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Abstract

KEY POINTS

  • Question: Are the rates of postoperative complications and hospital readmissions different when airway surgery for obstructive sleep apnea is performed in outpatient as compared to inpatient settings?
  • Findings: This propensity-matched analysis revealed that the rate of the composite postoperative complications, reoperations, and 30-day hospital readmissions were similar between inpatients and outpatients based on the length of stay at the health care facility.
  • Meaning: The findings from this study could be used to help triage patient’s length of stay at the health care facility.

Obstructive sleep apnea (OSA) is a common breathing disorder, which is recognized as an independent risk factor for a range of clinical conditions, such as hypertension, stroke, depression, and diabetes.1 Positive airway pressure (PAP) is the primary treatment for moderate-to-severe OSA.2–4 However, compliance with PAP remains a challenge. Upper airway surgery is an alternative treatment for patients with severe OSA.5 With increase in prevalence of OSA, there is an increase in airway surgical procedures for treatment of OSA.6

Drugs used to provide general anesthesia for the surgery (eg, sedative-hypnotics, opioids, and muscle relaxants) impair neural input to the upper airway muscles and therefore may worsen or even induce postoperative upper airway obstruction and apnea.7 In addition, these drugs also decrease the ventilatory response to hypoxemia and hypercarbia further exaggerating OSA.8 Furthermore, drug-induced airway obstruction and apnea prevent arousal caused by hypoxia and hypercarbia, which may have life-threatening consequences.9 Several large observational trials have reported a higher incidence of perioperative complications in OSA patients requiring general anesthesia.10,11 Airway surgery is of greater concern because postoperative airway swelling, and bleeding may further exacerbate the OSA-related complications. Given these concerns, there is controversy regarding the setting (ie, outpatient versus inpatient) in which to perform these surgical procedures.

The Society for Ambulatory Anesthesia (SAMBA) consensus statement provides guidance regarding selection of adult patients with OSA scheduled for outpatient surgery, which was based on a systematic review of published literature assessing perioperative complications in this patient population.12 However, the SAMBA consensus statement did not provide any guidance for OSA patients undergoing upper airway surgery due to limited evidence.12 On the other hand, the American Society of Anesthesiologists (ASA) does not recommend performing airway surgery on an outpatient basis.13 A recent consensus recommendation on perioperative care of patients with OSA undergoing upper airway surgery states that the data on outcomes after airway surgery performed in the outpatient settings are sparse.6 Because of low quality evidence, several recommendations regarding outpatient airway surgery were designated as weak.6

The aim of the study was to compare postoperative outcomes of patients undergoing airway surgery in the outpatient and inpatient settings based on the length of stay at the health care facility. Primary outcome was a composite of 30-day readmissions, reoperations, and/or postoperative complications.

METHODS

The University of Texas Southwestern Medical Center Institutional Review Board (IRB) exempted the study from full review because this is a retrospective study using public registry data that are Health Insurance Portability and Accountability Act compliant and do not identify hospitals, health care providers, or patients. Therefore, the IRB waived the requirement for written informed consent for this study. The study population consisted of adult patients with a principal diagnosis of obstructive sleep disorders undergoing one or more elective airway surgical procedures for the treatment of OSA. Data were extracted from the 2011–2017 Participant Use Data Files (PUF) of the American College of Surgeons National Surgical Quality Improvement (ACS-NSQIP). Of note, trained and certified Surgical Clinical Reviewers extract the data from patients’ chart, and interrater reliability audits are conducted regularly to assess the quality of the data collected. The ACS-NSQIP PUF files contain data on over 300 variables, including preoperative risk factors, intraoperative variables, and up to 30-day postoperative mortality and morbidity outcomes for patients undergoing major surgical procedures in both inpatient and outpatient settings. Detailed documentation about the ACS-NSQIP program and data files can be found in reference 14. This article adheres to the applicable STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines.

Patient Selection and Characteristics

Patients with obstructive sleep disorders were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes 327.23, 780.53, and 780.57 from the 2011–2014 NSQIP databases, and International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes G47.30, G47.33, and G47.39 from the 2015–2017 databases. Airway surgical procedures for treatment of OSA were identified using appropriate current procedural terminology (CPT) codes present in the database (Appendix 1). Airway procedures were further categorized into 5 groups according to the anatomic location (nasal or sinus surgery; uvulopalatopharyngoplasty [UPPP], tonsillectomy, or other palate surgery; base of tongue procedures; maxillomandibular advancement; and tracheostomy). Emergency or nonelective cases, as well as patients transferred from acute care hospitals, nursing homes, chronic care, or intermediate care facilities were excluded from the analyses. Variables describing patient demographics (age, sex, race), clinical characteristics (chronic comorbid conditions, ASA physical status, history of smoking, functional status, presence of dyspnea, and chronic use of steroids), and procedural characteristics (anatomic level, complexity, and duration of surgery) were used for descriptive purposes and for risk adjustment. Surgical complexity was evaluated by measuring the sum of relative value units (RVUs) for the principal and secondary procedures,15 the number of concomitant procedures, and operative time. In addition, to assess the impact of multilevel surgery on outcomes, surgical procedures were classified into 2 groups: single-level (eg, UPPP [with or without adeno-tonsillectomy] alone) and multilevel surgery (eg, combination of UPPP and any sinus/nasal, base of tongue, or maxillomandibular procedures). Surgery setting was classified as outpatient if the length of hospital stay was 0 days or as inpatient if the length of stay was 1 day or longer.

The primary outcome for the study was a composite measure of any readmission (to the same or another hospital) for any reason, any reoperation, or any postoperative complication (neurologic, respiratory, cardiac, pulmonary embolism, acute renal failure, hemorrhage, surgical site infection, sepsis, or death) within 30 days of the principal surgical procedure. Subanalyses of readmissions within 1 or 7 days post procedure were further performed. Principal diagnoses indicating causes of hospital readmission were analyzed as secondary outcomes.

Statistical Analysis

Univariate analyses were performed to describe baseline characteristics of patients undergoing airway surgery for treatment of OSA in inpatient and outpatient settings. Continuous variables are summarized as means (standard deviations) or as medians and interquartile ranges for variables with heavily skewed distributions. Discrete variables are presented as frequencies and group percentages. Propensity scores derived from a logistic regression model were used to assemble a 1-to-1 matched cohort of patients undergoing inpatient or outpatient airway surgery. The logistic regression analysis was designed to model the probability of receiving outpatient versus inpatient surgery. Therefore, the outcome variable in the model was surgical setting. Covariates in the model for propensity score included demographics (age, sex, race, and Hispanic ethnicity), patient body mass index (BMI), ASA physical status, smoking status, presence of dyspnea, functional status, use of steroids for chronic conditions, chronic comorbidities (diabetes mellitus, chronic obstructive pulmonary disease, hypertension requiring medication, heart failure, chronic renal failure, bleeding disorders), and variables related to surgical complexity (single or multilevel surgery, operative time, and sum of RVUs). Propensity matching was done using a greedy nearest neighbor matching technique to sequentially match each observation for patients in the outpatient group with 1 observation for patients in the inpatient group. Matching criteria included a caliper = 0.2 (specifying that patients are matched only if the difference in the logits of the propensity scores is ≤0.2 times the pooled estimate of the common standard deviation of the logits of the propensity scores). Absolute standardized differences were calculated to assess postmatch balance between the propensity-matched groups. An absolute standardized difference equal to or smaller than 0.1 (10%) indicates appropriate balance of a baseline covariate between the groups.16 Differences in rates of the primary outcome (the composite 30-day hospital readmissions, reoperations, and/or postoperative complications) were assessed between the matched groups. The primary analysis was conducted using a multilevel generalized mixed linear regression analysis (patients were considered nested within propensity-matched groups) to account for the correlated nature of the matched data, and odds ratios (OR) with 95% confidence intervals (CIs) were calculated for the primary outcome. Comparisons between inpatient and outpatient groups regarding readmissions, reoperations, and frequent causes of readmissions were performed for descriptive or exploratory purposes only.

To test the robustness of our statistical approach, a sensitivity analysis using inverse probability treatment weighting (IPTW) on propensity scores was performed.17 The propensity scores were derived from a logistic regression model including the same variables used in the propensity-matching analysis. Each observation on the inpatient and outpatient groups was weighted based on the propensity scores to adjust for baseline characteristics, and the weights were used to estimate the average treatment effect. A binary logistic regression model was used to compare differences in the primary outcome between the weighted samples. Robust standard errors were used to account for within-subject correlation induced by the weighting approach.17 An additional exploratory stratified analysis was performed on the weighted data to test the interaction between surgical setting and level of surgery (single- or multi-level) on the primary outcome. In addition, the rates of the primary outcome were compared between surgical settings within each level of singe/multilevel surgery.

We used all the data on airway surgery cases available from the 2011–2017 NSQIP databases. Based on previous studies reporting incidences of our primary outcome of about 2%–8%,18 a power analysis was performed with the assumption that a 3 percentage point difference in the primary outcome (eg, 3% in inpatient versus 6% in outpatient) would be clinically significant. For a McNemar’s test on the matched sample, with a 0.05 type I error, we estimated that a total of 950 pairs of patients would provide a power of 0.88 to detect the proposed effect size. All the analyses were conducted using SAS 9.4 statistical software (Cary, NC). A significance level of 0.05 was defined for the analyses.

RESULTS

A total of 3208 airway surgery cases were identified (1049 [32.7%] outpatient and 2159 [67.3%] inpatient). Inpatients were older; had higher incidence of hypertension, diabetes, pulmonary disease, dyspnea, and smoking; had larger BMI and ASA physical status; and had longer and more complex procedures (Table 1). Morbid obesity (BMI >40 kg/m2) was more prevalent in inpatients compared to outpatient settings (15.3% vs 10.5%, respectively). UPPP was performed in more than 96% of patients having surgery either in outpatient or inpatient settings. Nasal surgical procedures were most frequently performed concomitantly with UPPP both in inpatient (33.1%) as in outpatient (29.4%) settings. Base of tongue surgery was the second most common procedure done in combination with UPPP. However, this type of combined surgery was found in 14.5% of inpatient compared to 4.8% of outpatient cases (P < .0001).

Table 1. - Baseline Characteristics of Patients Undergoing Sleep Apnea Surgery: Nonmatched and Matched Samples
Nonmatched sample Propensity-matched sample
Characteristic Inpatient (n = 2159) Outpatient (n = 1049) P value Inpatient (n = 987) Outpatient (n = 987) Standardized difference
Age, y, mean (SD) 43.3 (12.3) 40.2 (12.6) <.0001 41.0 (12.4) 40.6 (12.4) 0.037
Body mass index, mean (SD) 33.3 (7.5) 31.8 (7.7) <.0001 32.2 (7.5) 31.90 (7.7) 0.041
Body mass index categories, kg/m2 <.0001 0.023
 <25 172 (8.0) 114 (10.9) 96 (9.7) 101 (10.2)
 25–<30 594 (27.5) 359 (34.2) 325 (32.9) 336 (34.0)
 30–<40 1062 (49.2) 466 (44.4) 451 (45.7) 443 (44.9)
 40–<50 271 (12.5) 87 (8.3) 92 (9.3) 84 (8.5)
 50+ 60 (2.8) 23 (2.2) 23 (2.3) 23 (2.3)
Female sex 554 (25.7) 309 (29.5) .0229 284 (28.8) 280 (28.4) 0.009
Race <.0001 0.000
 White 1349 (62.5) 717 (68.4) 658 (66.7) 667 (67.6)
 Black 241 (11.2) 111 (10.6) 111 (11.3) 106 (10.7)
 Other 136 (6.3) 85 (8.1) 78 (7.9) 78 (7.9)
 Unknown 433 (20.1) 136 (13.0) 140 (14.2) 136 (13.8)
Hispanic ethnicity 151 (7.0) 110 (10.5) .0007 92 (9.3) 99 (10.0) 0.025
ASA physical status <.0001 0.046
 I 59 (2.7) 77 (7.3) 48 (4.9) 56 (5.7)
 II 1157 (53.6) 652 (62.1) 619 (62.7) 617 (62.5)
 III 920 (42.6) 311 (29.6) 311 (31.5) 305 (30.9)
 IV 23 (1.1) 9 (0.9) 9 (0.9) 9 (0.9)
Diabetes mellitus 237 (11.0) 73 (7.0) .0003 73 (7.4) 72 (7.3) 0.003
Chronic pulmonary disease 35 (1.6) 6 (0.6) .0131 5 (0.5) 6 (0.6) 0.010
Heart failure 4 (0.2) 1 (0.1) .5446 2 (0.2) 1 (0.1) 0.027
Hypertension 717 (33.2) 270 (25.7) <.0001 265 (26.8) 263 (26.3) 0.004
Steroid use for chronic condition 41 (1.9) 8 (0.8) .0138 8 (0.8) 7 (0.7) 0.090
Bleeding disorders 5 (0.2) 4 (0.4) .4859 2 (0.2) 3 (0.3) 0.018
Current smoker 375 (17.4) 142 (13.5) .0056 126 (12.8) 137 (13.9) 0.030
Dyspnea 107 (5.0) 29 (2.8) .0039 32 (3.2) 29 (2.9) 0.016
Dependent functional status 17 (0.8) 5 (0.5) .3171 5 (0.5) 5 (0.5) 0.000
Level of sleep surgery procedure
 UPPP 2089 (96.8) 1032 (98.4) .008 987 (100) 987 (100) 0.000
 Nasal 699 (32.4) 309 (29.5) .0947 287 (29.1) 293 (29.7) 0.013
 Palate 35 (1.6) 28 (2.7) .0447 18 (1.8) 19 (1.9) 0.008
 Maxilla 35 (1.6) 1 (0.1) <.0001 0 (0.0) 0 (0.0) 0.000
 Base of tongue 354 (16.4) 61 (5.8) <.0001 60 (6.1) 50 (5.1) 0.035
 Tracheotomy 7 (0.3) 0 (0) .1039 0 (0.0) 0 (0.0) 0.000
Multilevel surgery 895 (42.8) 347 (33.6) <.0001 337 (34.1) 335 (33.9) 0.004
No. of concomitant procedures, median (IQR) 2.0 (1–3) 2.0 (1–3) <.0001 2.0 (1–3) 2.0 (1–3) 0.003
Sum of RVUs, mean (SD) 15.4 (8.3) 12.4 (7.1) <.0001 12.8 (6.1) 12.6 (6.9) 0.027
Operation time (min), median (IQR) 55 (36–85) 39 (26–58) <.0001 43 (29–62) 40 (26–59) 0.058
Values for categorical variables are number (percent). Standardized differences <0.10 are considered not clinically important. Standardized difference is the difference in the means or proportions of a variable between 2 groups divided by an estimate of the pooled standard deviation of that variable.
Abbreviations: ASA, American Society of Anesthesiologists; IQR, interquartile range; RVU, relative value unit; SD, standard deviation; UPPP, uvulopalatopharyngoplasty.

The overall rate of the composite of readmissions, reoperations, and/or complications in the whole unmatched sample was 6.4% (6.8% and 5.5% in inpatients and outpatients, respectively). Of note, mortality at 30 days occurred in only 1 patient (0.03%). The propensity-matching algorithm produced a sample of 987 inpatients (45.7% of all inpatients) and 987 outpatients (94.1% of all outpatients), well balanced on the available baseline characteristics (Table 1). The overall incidence of postoperative outcomes in the propensity-matched analysis is described in Table 2. The incidence of the primary outcome of composite of hospital readmissions, reoperations, and/or postoperative complications was not significantly different between the inpatient and outpatient groups (6.2% and 5.9%, respectively; P = .77). The most frequent cause of readmissions was postoperative bleeding, followed by respiratory complications and surgical site infection (Table 2).

Table 2. - Postoperative Complications in a Propensity-Matched Sample of Patients Undergoing Airway Surgery for Obstructive Sleep Apnea in Inpatient and Outpatient Settings
Outcomes Inpatient
n (%)
Outpatient
n (%)
OR (95% CI) (inpatient versus outpatient) P a
Primary outcome: 30-d readmissions/reoperations/complications 61 (6.2) 58 (5.9) 1.06 (0.73-1.53) .77
Secondary outcomes
 30-d readmissions 31 (3.1) 36 (3.6) 0.86 (0.52-1.40) .54
  Readmissions within 24 h 3 (0.3) 9 (0.9)
  Readmissions within 7 d 15 (1.5) 14 (1.4)
 Reoperations 33 (3.3) 36 (3.6) 0.91 (0.56-1.48) .72
 30-d complications 27 (2.7) 22 (2.2) 1.23 (0.69-2.18) .47
Most frequent causes of readmission
 Bleeding complications 10 (1.0) 13 (1.3)
 Respiratory complications 7 (0.7) 2 (0.2)
 Surgical site infection 4 (0.4) 3 (0.3)
 Urinary tract infection 2 (0.2) 1 (0.1)
 Other complications 5 (0.5) 4 (0.4)
Abbreviations: CI, confidence interval; OR, odds ratio.
aP value from multilevel generalized mixed linear regression analyses.

The IPTW sensitivity analysis included 3098 patients (1020 outpatients and 2078 outpatients) who were well balanced on baseline characteristics after propensity score weighting. Accounting for weighting and within-subject correlation, there were no significant differences in the incidence of the composite primary outcome between the groups (6.3% vs 5.6% in inpatients and outpatients, respectively; OR [95% CI], 1.13 [0.80-1.60]; P = .488). The analysis on weighted data stratifying by anatomic complexity of surgery revealed that the interaction between surgical setting and level of surgery was not statistically significant (P = .374). In addition, the rate of the primary outcome was not statistically different between surgical settings either for single-level surgery (6.4% vs 5.1% in inpatients and outpatients, respectively; OR [95% CI], 1.28 [0.82-2.02]; P = .276) or multilevel procedures (6.0% vs 6.4% in inpatients and outpatients, respectively; OR [95% CI], 0.93 [0.55-1.60]; P = .806).

DISCUSSION

The main finding of this study is that the rate of the composite of 30-day postoperative complications, reoperations, and/or readmissions after airway surgery was not significantly different in patients who had the procedure in inpatient compared with outpatient surgical settings. Our analyses also revealed that the incidence of complications and readmissions in OSA patients undergoing airway surgery are very low, which is in line with previous reports.6,19

Our propensity scores algorithm created a matched subsample of inpatients that was comparable to the outpatients regarding all measured baseline characteristics, including variables that are strong predictors of outcomes. Postoperative complications and hospital readmission rates in these matched samples of inpatients and outpatients were not significantly different. Our results were consistent when we performed the analysis using IPTW. The meaning of our findings is that when similar airway surgery procedures were performed in outpatient settings on patients who, on average, had very similar characteristics to those who had surgery in inpatient settings, the overall likelihood of 30-day complications and/or readmissions was not significantly different between the surgical settings. An important question arising from our findings is what proportion of OSA airway surgery cases currently performed in inpatient settings could be moved to outpatient settings with no detriment in outcomes? We may speculate that at least some cases done in inpatient settings could be performed in the outpatient setting, as shift to the outpatient setting has been described before to improve 30-day outcomes as well as significant costs savings.20 However, the nature of our study does not allow us to provide a definitive answer to this question, which needs to be resolved by future prospective studies. Furthermore, this study does not allow us to determine the venue of the outpatient setting (ie, free-standing ambulatory surgery center [ASC], hospital-based outpatient department [HOPD], or 23-hour stay facility).

We also found that higher ASA physical status and base of tongue surgery were associated with higher 30-day readmission rates, while diabetes mellitus, increased operative time, and larger sum of RVUs were associated with higher incidence of postoperative complications (data not shown). These observations suggest that patients with high ASA physical status (III or IV) and/or diabetes scheduled for airway procedures that include base of tongue surgery or long multiple operations may be at higher risk of postoperative complications. These factors could be used for triaging patients to appropriate surgical setting (ie, inpatient versus outpatient).

Our findings contribute to recent consensus recommendations for selection of airway surgery on an outpatient basis, which were designated as “weak” due to limited evidence. These recommendations state that outpatient setting is appropriate for nasal surgery, minimally invasive surgery of the palate and/or base of tongue, and hypoglossal nerve stimulation.21 In contrast, overnight stay was recommended for invasive palatal surgery (UPPP) unless determined otherwise by the surgeon and/or anesthesiologist,22 invasive lower pharyngeal surgery (midline glossectomy, genioglossus advancement, transoral robotic surgery, hyoidthyroidpexia, partial resection of the epiglottis), and maxillofacial surgery (maxillomandibular advancement).5,6,23

This retrospective study represents analysis of the ACS-NSQIP database24 while previous studies evaluating the feasibility of airway surgery on an outpatient basis used administrative databases such as the Medicaid25 and National Survey of Ambulatory Surgery databases,19 which are limited by the lack of clinical data and the rigor in data collection.

Several previous case series have identified postoperative pain and nausea and vomiting as common reasons for readmission.23,25 Therefore, nonopioid analgesics such as acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2)–specific inhibitors, dexamethasone, as well as local/regional analgesia, which are opioid-sparing, have been recommended as routine management.26 In our study, however, acute pain and postoperative nausea/vomiting were not among the top 5 reasons for readmission. In contrast, postoperative bleeding was the most common postoperative complication among inpatients and outpatients. Postoperative bleeding may cause laryngospasm, which may be avoided by performing tracheal extubation after ensuring patient response (ie, appropriate response to commands). Because some of the blood may be swallowed, it might increase the potential for nausea and vomiting, which could be reduced by aggressive prophylaxis with at least 2 or 3 antiemetics. Rapid return of consciousness and protective airway reflexes are important to avoid postoperative complications. This can be achieved by avoiding routine use of midazolam premedication and use of short-acting sedative-hypnotics, opioids, and neuromuscular blocking agents at the lowest possible doses.

Postoperative complications, particularly respiratory complications can occur and therefore, adequate vigilance and monitoring for episodes of apnea and desaturations as well as sedation. In addition, patients should be maintained in semiupright (30° head-up) position to avoid airway obstruction, when possible. PAP (oral or full facemask) may be used where appropriate on consultation with the surgeon.6 It is necessary to educate patients and their family (or caregivers) regarding the need for increased vigilance at home. Also, patients should be advised against sleeping in the supine position. The deleterious effects of opioids must be emphasized, and patients should be asked to limit opioid use.27

There is some controversy regarding PAP use after airway surgery.6 PAP might reduce the risk of postoperative airway complications by decreasing upper airway edema and increasing lung mechanics. It is recommended that full facemask PAP may be used after nasal surgery, if it is tolerated and not contraindicated.6 However, PAP is not recommended after maxillofacial surgery.6 Contraindications for PAP include functional rhinoplasty or functional endoscopic sinus surgery, and orbital or skull base defect (due to concerns of orbital emphysema and pneumocephalus).6

This study has several limitations. Information on severity of OSA (eg, apnea-hypopnea index and oxygen nadirs) could not be obtained. Also, it does not provide information on the type and amount of medications administered as well as the incidence and degree of oxygen desaturation in the perioperative period. Long-term consequences of oxygen desaturation (eg, postoperative cognitive dysfunction and neurological events) could not be obtained. It is well known that administrative databases have inherent inconsistences in coding of the identifiers, and thus, liable to possible omissions or errors in data entry. Errors may be true for actual coding of cases into appropriate ICD codes as well as complication codes. Information about diagnosis or treatment for OSA is not collected in the NSQIP registry. Furthermore, it is challenging to study risks of surgical complications in OSA cases because of the wide variations of the definitions used for complications among studies and the low incidence of life-threatening complications, which requires a large sample size to analyze with significance. Also, this study does not allow us to specify the venue of outpatient surgery (ie, free-standing ASC, HOPD, or 23-hour stay facility).

In summary, this study shows that the measured complications and 30-day readmission rates after airway surgery for treatment of OSA is very low. In the matched sample, there are no differences in adverse outcomes between inpatient and outpatient setting. We have identified risk factors that are associated with higher postoperative adverse events, which include higher ASA physical status, presence of diabetes mellitus, tongue-based surgery, duration of surgery, and greater complexities of surgical procedures or multiple surgical procedures. These risk factors could be used to determine the need for overnight stay. It is imperative that clinicians proceed with caution and decision to perform airway surgery on an outpatient basis should be individualized based on the anesthesiologist and surgeon comfort as well as the type of outpatient setting (ie, ASC, HOPD, or 23-hour stay facility). Adequately designed prospective studies are necessary to confirm the retrospective observations of this study as well as assess the outcomes based on the type of outpatient facilities.

DISCLOSURES

Name: Eric B. Rosero, MD, MSc.

Contribution: This author helped with conception and design of study, analysis and interpretation of data, drafting of the manuscript, critical revision of the manuscript for important intellectual content, statistical analysis, final approval of the version to be published, agreement to be accountable for all aspects of the study.

Conflicts of Interest: None.

Name: Girish P. Joshi, MBBS, MD, FFARCSI.

Contribution: This author helped with conception and design, interpretation of data, drafting of the manuscript, critical revision of the manuscript for important intellectual content, final approval of the version to be published, agreement to be accountable for all aspects of the study.

Conflicts of Interest: G. P. Joshi has received honoraria from Baxter Pharmaceuticals and Pacira Pharmaceuticals.

This manuscript was handled by: Toby N. Weingarten, MD.

Appendix 1. - CPT Codes of Procedures Included in Study
Group of surgery CPT codes
Uvulopalatopharyngoplasty, tonsillectomy, or adenoidectomy 42145, 42950, 42140, 42821, 42826, 42831
Nasal and sinus surgery 30801, 30802, 30930, 30130, 30140, 30520, 30540, 30400, 30410, 30420, 30450, 30465, 31020, 31030, 31040, 31255, 31288, 31276, 31200, 31201
Other palate surgery 42299, 42892, 42890, 42104, 42106, 42107, 42120, 42235
Base of tongue surgery 21199, 21120, 21121, 21122, 21123, 41120, 41130, 42870, 21685, 41512, 41530, 31420
Maxillomandibular advancement 21141, 21143, 21193, 21194, 21195, 21196, 21198, 21199, 21206
Tracheostomy 31600, 31610
Abbreviation: CPT, current procedural terminology.

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