Research AESXXX / X Aesthetic Surgery JournalMiller et al

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1 525394AESXXX / X Aesthetic Surgery JournalMiller et al research-article2014 Research Evaluation of the American Society of Anesthesiologists Physical Status Classification System in Risk Assessment for Plastic and Reconstructive Surgery Patients Travis J. Miller, BS; Haneol S. Jeong, BA, BBA; Kathryn Davis, PhD; Anoop Matthew, MPH; Jerzy Lysikowski, PhD; Min-Jeong Cho, BS, BA; Gary Reed, MD; and Jeffrey M. Kenkel, MD Aesthetic Surgery Journal 2014, Vol. 34(3) The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journalspermissions.nav DOI: / X Abstract Background: The American Society of Anesthesiologists Physical Status (ASA-PS) classification is a ranking system that quantifies patient health before anesthesia and surgery. Some surgical disciplines apply the ASA-PS to gauge a patient s likelihood of developing postoperative complications. Objective: In this study, the authors analyze whether ASA-PS scores can successfully predict risk for postoperative complications in plastic and reconstructive operations. Methods: The authors retrospectively reviewed the charts of 1801 patient procedures and selected for inclusion 1794 complex plastic and reconstructive operations that took place at 1 of several academic medical institutions between January 2008 and January ASA-PS scores, patient comorbidities, and postoperative complications were analyzed. Percentile data were treated with tests for proportions. Nonpercentile data were analyzed through comparison of means (t test). Low-risk (ASA 1-2) and high-risk (ASA 3+) groups were compared with simple odds ratios. Results: For the 1430 women and 364 men in the patient cohort (average age, 49.5 years), the overall complication rate was 27.7%. When patients with complications were compared to those without, body mass index, operation time, recent major surgery, diabetes, hypertension, renal disease, cancer, and oral contraceptive use were statistically significant. After high-risk (n = 398) and low-risk (n = 1396) groups were identified, infection, delayed wound healing, deep vein thrombosis, and overall complications had significantly increased incidence in the high risk group. Notably, deep vein thrombosis displayed the highest odds ratio (4.17) and a complication rate increase from 0.93% to 3.77%. Conclusions: ASA-PS scores can be used either as substitutes for or as adjuncts to questionnaire-based risk assessment methods in plastic surgery. In addition to deducing significant findings for deep vein thrombosis incidence, ASA-PS scores hold important predictive associations for multiple non venous thromboembolism complications, providing a broader measurement for postoperative complication risks. Level of Evidence: 4 Keywords complications, risk assessment, physical status classification, postoperative complications, anesthesia, aesthetic surgery Accepted for publication September 18, The American Society of Anesthesiologists (ASA) maintains a system called the Physical Status (PS) classification to preoperatively assess the systemic health of individual patients. Its original intended application was purely statistical 1 ; however, many anesthesiologists and nurse anesthetists administer the ASA-PS as a proxy for risk assessment of anesthesia and surgery. 2 The ASA-PS has also played an From the University of Texas Southwestern Medical Center, Dallas, Texas, USA. Corresponding Author: Dr Jeffrey M. Kenkel, Department of Plastic Surgery, University of Texas Southwestern Medical Center, 1801 Inwood Road, Dallas, TX , USA. jeffrey.kenkel@utsouthwestern.edu

2 Miller et al 449 important role in policy making, performance evaluation, resource allocation, and anesthesia service reimbursements. Despite studies reporting scoring method subjectivity and inconsistencies among anesthesiologists in assigning ASA-PS scores, 3,4 the utilization of these scores for these purposes continues perhaps because additional research confirms a positive association between scores and patient outcomes, with increasing ASA-PS scores correlating with increased risk for postoperative complications. 5-7 Within plastic surgery, prior research established the Caprini risk assessment model later, the modified Davison-Caprini risk assessment model as an effective method of assessing patients for peri- and postoperative thromboembolic risk. 8 Further studies expanded the incorporated list of variables, but the analysis still is limited to thromboembolism risk. 9,10 Although studies have independently analyzed factors contributing to other postoperative complications such as infection, seroma, hematoma, delayed wound healing, wound dehiscence, necrosis, and erythema no similar dedicated risk identification system exists for these issues. However, as an assessment of systemic disease linked to numerous postoperative complications, the ASA-PS system might function in this role by dividing patients into risk categories that both guide preoperative assessment and standardize treatment protocols. Although the ASA-PS system has attained widespread adoption and practitioners increasingly rely on the score to predict surgical risk, a prospective study correlating ASA-PS scores to outcomes from plastic surgery procedures has not yet been performed. To help fill this gap in the literature, we conducted a retrospective chart review. By measuring the strength of predictive association, our study analyzed how well ASA scores evaluate a patient s risk for postoperative complications. Methods After obtaining approval from the University of Texas Southwestern s (Dallas, Texas) Institutional Review Board, we performed retrospective chart review of 1801 consecutive plastic surgery procedures. Ultimately, the recorded ASA-PS score was deemed unreliable in 7 patient encounters due to inconsistencies in the medical record; these were thus excluded from further analysis, yielding a final cohort of 1794 reconstructive and/or body-contouring procedures (as determined by Current Procedural Terminology codes) performed on patients between January 2008 and January 2012 (Table 1). The procedures were notable for their complexity and lengthy surgical times. Operations were performed at facilities associated with University of Texas Southwestern Medical Center (Parkland Memorial Hospital, St Paul University Hospital, Zale Lipshy University Hospital, or the Outpatient Surgery Center all located in Dallas, Texas) by 1 or more of 19 faculty members Table 1. Collected Current Procedural Terminology Codes No Flaps: Muscle, head Flaps: Trunk Flaps: Upper extremity Flaps: Lower extremity Description Flaps: Free muscle with microvascular anastomosis Flaps: Free skin with microvascular anastomosis Flaps: Free facial flap with microvascular anastomosis Other: Superficial musculoaponeurotic system flap Other: Excision, excessive skin and subcutaneous tissue; abdomen, infraumbilical, panniculectomy Other: Thigh Other: Leg Other: Hip Other: Buttock Other: Arm Other: Forearm or hand Other: Submental fat pad Other: Other area Other: Excision, excessive skin and subcutaneous tissue, abdomen (use in conjunction with 15830) Suction-assisted lipectomy, trunk Suction-assisted lipectomy, upper extremity Suction-assisted lipectomy, lower extremity Delayed insertion of breast prosthesis following mastopexy, mastectomy, or in reconstruction (for supply of implant, use 99070; for preparation of custom breast implant, use 19396) Breast reconstruction, immediate or delayed, with tissue expander (including subsequent expansion) Breast reconstruction with latissimus dorsi flap, without prosthetic implant (for insertion of prosthesis, use also) Breast reconstruction with free flap (includes harvesting of the flap, microvascular transfer, closure of the donor site, and inset shaping of the flap into a breast) Breast reconstruction with other technique Breast reconstruction with transverse rectus abdominis myocutaneous flap, single pedicle, including closure of donor site Breast reconstruction with transverse rectus abdominis myocutaneous flap, single pedicle, including closure of donor site (with microvascular anastomosis supercharging) associated with the University of Texas Southwestern Department of Plastic Surgery.

3 450 Aesthetic Surgery Journal 34(3) Table 2. Definition of Individual Complications Table 3. Complication Rate by Procedure Type, n Complication Infection Dehiscence Description Evidence of infection at wound site, either culture driven or purulent seepage Complete full-thickness wound rupture along surgical suture in the first 30 days postsurgery Procedure Patients With Any Complication Flap-based procedure Breast reconstruction Excision (excessive skin tissue) Erythema Necrosis Seroma Hematoma Delayed wound healing Flap failure Variables In addition to ASA scores, patient comorbidity information was recorded from the medical records including diabetes, smoking status, coronary artery disease, history of myocardial infarction, chronic obstructive pulmonary disease, hypertension, renal disease, cancer history, HIV/ AIDS status, and prior history of deep vein thrombosis (DVT). Surgical outcomes were assessed over a period of approximately 30 days. A complication was indicated by any of the following in the postoperative period, whether it occurred independently or in conjunction with other problems: infection, dehiscence, erythema, necrosis, seroma, hematoma, delayed wound healing, or DVT (Table 2). Statistical Analysis Evidence of excessive rubor and inflammation at wound site without obvious infectious cause Unexpected tissue death at wound site Development of serous fluid pocket(s) at wound site Development of extravascular blood pocket(s) at wound site Noted delay in resolution of surgical wound as appropriate for site (superficial wound breakdown), excluding mechanical complications of separation along suture lines Inability of viable grafting of a tissue flap, either partial or total For comorbidity analysis, 2-tailed proportion tests were performed on percentile data to determine differences between complication-free and complication-present encounters for the following variables: sex, body mass index (BMI) > 25 and > 40, recent surgical history (< 1 month), current smoking status, diabetes, chronic obstructive pulmonary disease / other lung disease, coronary artery disease / other heart disease, hypertension, renal disease, cancer history, HIV/AIDS status, and history of DVT. Nonpercentile data, including age, BMI, and operation time, were analyzed by comparison of means (Student t test). At the time of each procedure, the attending anesthesiologist assessed ASA scores, which the study authors recorded retrospectively from the medical charts and correlated to complications; to achieve this, patient encounters were separated into low- and high-risk categories based on ASA scores, with 1 or 2 representing low risk and 3 to 5 denoting high risk. These low- and high-risk groups were compared for Suction-assisted lipectomy Delayed breast prosthesis Removal of facial wrinkles 35 5 Total complication rates through simple odds ratios (ORs). ORs were calculated for overall complications, as well as individually for dehiscence, infection, erythema, seroma, hematosis, necrosis, delayed wound healing, and DVT. Sensitivity and specificity were also calculated with 2 2 contingency tables of risk groups for each noted complication. Data Storage and Analysis Data were recorded and stored in Microsoft Excel (Redmond, Washington). Patient information was de-identified after primary data collection; patient identifiers were stored on a secure network with additional password encryption built into the file itself. All tests for proportions, comparison of means, ORs, and associated significance levels were calculated through the MedCalc statistical software program (Ostend, Belgium). P values were considered significant at the α = 0.05 level. Results Patients in our cohort ranged in age from 13 to 86 years, with an average age of 49.5 years. There were 1430 women and 364 men included in the study. Ethnicity was not considered as a variable because it was not consistently represented in the patient charts. Of the 1794 unique encounters included in the study, 577 were flap-based procedures (incidences of any complication, n = 196); 438, breast reconstructions (n = 173); 309, excess skin tissue removal (n = 73); 244, liposuction (n = 31); 191, delayed breast prosthesis procedures (n = 19); and 35, facial wrinkle treatments (n = 5) for an overall complication rate of 27.70% (Table 3). The complication rates for patients grouped by ASA-PS score were also assessed and are shown in Table 4. When individual risk factors were compared between patients who experienced complications and those who did not, BMI, operation time, recent major surgery, diabetes, hypertension, renal disease, cancer, and oral contraceptive use all were statistically significant between the 2 groups (Table 5). After patients were categorized as either low or high risk, 1396 encounters were allocated to the low-risk

4 Miller et al 451 Table 4. Complication Rate by American Society of Anesthesiologists Score Score Encounters, n Any Complication, % category (ASA-PS 1 or 2) and 398 to the high-risk category (ASA-PS 3, 4, or 5). Infection, delayed wound healing, DVT, and overall complication had significantly increased incidence for the high-risk group. Notably, DVT displayed the highest increased rate (OR = 4.17), paralleling a similar rise in base complication rates from 0.93% to 3.77%. Discussion The ASA-PS was originally designed in 1941 as a 6-tiered scheme with a 7th added soon thereafter; the authors provided clear guidance on the types of systemic diseases that merited classification on 1 level or another. 1 The more modern iteration still applied today instituted some minor changes and removed guidance for practitioners on patient disease classification and currently has 6 categories. 14 Despite these changes and the resulting inconsistencies they generated, the ASA-PS holds several distinct advantages over rival systems in assessing patient risk. Primarily, it can be assessed preoperatively and with minimal use of valuable clinical resources. Also, it does not require a 24-hour sampling period like the Acute Physiology and Chronic Health Evaluation Complication risks can be determined without knowing the outcome beforehand, unlike the Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity system. 16 In spite of previously noted limitations, these inherent advantages have allowed the ASA-PS scheme to become the most widely used risk assessment system in anesthesia, 7 with consistent crossover into surgical risk assessment. Our study analyzed whether the ASA-PS could be successfully adapted to predict complications prioritized in plastic surgery operations or whether previously identified inconsistencies in ASA-PS scores would prevent such an endeavor. 2-4 ASA-PS System and Venous Thromboembolism Events Patients are at risk of developing a range of clinically diverse complications as a result of surgical intervention. Among the most serious is venous thromboembolism (VTE; which includes both DVT and pulmonary embolism) because of its high rate of occurrence, diversity of presentation, and severity of impact. Left untreated, rates of affliction can range from 25% to 33% in general surgery 17 and up to 41% to 85% following many orthopedic procedures. 18 In plastic surgery, the literature reports pulmonary embolism as the primary cause of death following liposuction (23% of all deaths) 19 and the cause of up to 63.6% of postoperative deaths following office-based procedures secondary to thromboembolism. 20 More recent work has proposed lower but still worrisome rates of incidence. 21,22 Compounding the prevalence of VTE is that up to twothirds of those complications may be clinically silent, 23 and within the first hour that a pulmonary embolism transpires, mortality reaches up to 10%. Even survivors are often afflicted with permanently damaged venous systems (a condition called postthrombotic syndrome). 24 The widespread nature of VTE prompted the Plastic Surgery Foundation s Research Oversight Committee in 2008 to make VTE identification and prevention a priority, leading to the Venous Thromboembolism Prevention Study. 24 Given the severity of VTE occurrence in plastic surgery, the viability of any risk assessment method in this field depends on its ability to accurately categorize patients according to their likelihood of developing VTE. Our study with an odds ratio (OR) of 4.17 and P value of.0002 (Table 6) demonstrated a significant predictive association between risk classification (high vs low) and VTE rates. This is in concord with prior studies, in which the ASA-PS score was identified as a significant risk factor for thromboembolic event incidence. 25,26 Our data notably demonstrated a link between oral contraceptive pill (OCP) use and general rates of complication. While no separate analysis for OCP use and DVT/pulmonary embolism incidence was conducted, the link between the 2 is well characterized. US federal law requires OCP manufacturers to include a Food and Drug Administration black box warning indicating that these products increase the risk of venous coagulation. Furthermore, the relationship between OCP and DVT incidence has been well researched generally 27 and in the context of outpatient plastic surgery procedures. 28 However, a potential relationship between OCP use and general postoperative complications has not been established. Interestingly, despite this potential increase in risk, our data reflected that OCP use correlated with fewer postoperative complications. OCP use is unlikely a direct cause of the decreased incidence, and we speculate that confounding factors including selectivity for a younger (premenopausal) age and better health maintenance contribute to the decreased complication rate in OCP users. Additionally, unlike other researchers, we collapsed multiple ASA-PS levels into high- and low-risk strata; doing

5 452 Aesthetic Surgery Journal 34(3) Table 5. Univariate Analysis of Patient Cohort Patients Risk Factor Without Complications With Any Complication P Value (Any Complication) Patients, n Age, mean Female, % Body mass index, mean <.0001 * > 25, % * > 40, % * OR time, mean <.0001 * Major surgery 1 month prior, % * Smoking, % Diabetes, % * COPD/pulmonary, % HTN, % * CAD, history of MI, or other cardiovascular event, % Renal disease, % * Cancer, % * HIV/AIDS, % History of DVT/PE, % Women, n Oral contraceptive use, % * Abbreviations: CAD, coronary artery disease; COPD, chronic obstructive pulmonary disease; DVT, deep vein thrombosis; HIV/AIDS, human immunodeficiency virus/acquired immune deficiency syndrome; HTN, hypertension; MI, myocardial infarction; OR, operating room; PE, pulmonary embolism. *P <.05. so generated greater clarity of information given insufficient data points at the distribution extremes. Further investigation involving a multicenter design is necessary to generate numbers strong enough to stratify ASA-PS risk levels (1-5) while preserving statistical power. Furthermore, we did not attempt to compare the ASA-PS system against the current standard for VTE risk assessment: the modified Caprini-Davison system. A future study could pursue this strategy to provide side-by-side results and generate comparative conclusions. Application to Non-VTE Events The 1941 edition of the ASA-PS provided specific examples to compensate for vague rank descriptions, 1 and this specificity was lost with the transition to the 5-tiered revisions implemented in 1961 (Table 7). Newer iterations have attempted to rectify this by substantially clarifying grading criteria to more accurately place patients into risk strata (Table 8). However, both forms maintain the central focus of the ASA-PS system: providing a broad estimation of patient risk. As measurement of systemic disease and not a single condition, the ASA-PS is uniquely positioned to monitor patient risk for numerous potential postoperative complications. Single-condition risk models such as the Caprini method for VTE analysis do ask questions indicative of systemic risk, such as age and BMI 29 ; however, the model s variable weighting process may augment predictive power for the condition of interest (VTE) at the expense of others (infection, delayed wound healing, etc). Independent analysis of individual conditions has identified systemic risks common to multiple complications: In particular, age and BMI have been positively associated with dehiscence, 11 necrosis, 12 and infection. 30 Among our study s stated purposes was to investigate to what extent the ASA-PS system incorporated clinical indications of

6 Miller et al 453 Table 6. Odds Ratios for Individual Complications According to American Society of Anesthesiologists Score Stratification Dehiscence Yes No Infection Yes No Erythema Yes No Low risk Low risk Low risk High risk High risk High risk Odds ratio (P) 1.09 (.71) Odds ratio (P) 1.91 (.0003 * ) Odds ratio (P) 0.99 (.967) Sensitivity 0.72 Sensitivity 0.75 Sensitivity 0.58 Specificity 0.40 Specificity 0.41 Specificity 0.39 Seroma Yes No Hematoma Yes No Delayed Healing Yes No Low risk Low risk Low risk High risk High risk High risk Odds ratio (P) 1.25 (.290) Odds ratio (P) 1.41 (.316) Odds ratio (P) 2.19 (.004 * ) Sensitivity 0.26 Sensitivity 0.82 Sensitivity 0.38 Specificity 0.78 Specificity 0.40 Specificity 0.78 Necrosis Yes No DVT Yes No these systemic characteristics. In essence, we sought to know whether ASA-PS stratification incorporated these systemic variables to the point where it would generate predictive associations for individual complications. Our data demonstrated a significantly increased risk for suffering a general postoperative complication with increasing ASA-PS scores (OR = 1.53, P =.0005), a finding demonstrated in prior literature across multiple disciplines. 5,31-33 Any Complication Yes No Low risk Low risk Low risk High risk High risk High risk Odds ratio (P) 0.82 (.478) Odds ratio (P) 4.17 (.0002 * ) Odds ratio (P) 1.53 (.0005 * ) Sensitivity 0.19 Sensitivity 0.54 Sensitivity 0.28 Specificity 0.78 Specificity 0.78 Specificity 0.8 Abbreviation: DVT, deep vein thrombosis. *P <.05. Table 7. American Society of Anesthesiologists Physical Status Classification (1961) Level and Description 1: A normal healthy patient 2: A patient with mild systemic disease 3: A patient with severe systemic disease that limits activity, but is not incapacitating 4: A patient with an incapacitating systemic disease that is a constant threat to life 5: A moribund patient not expected to survive 24 hours with or without operation (In the event of an emergency operation, an E is placed after the number ranking.) However, with those same scores, we were less able to parse risk differences for individual complications outside of infection (OR = 1.91, P =.0003), delayed wound healing (OR = 2.19, P =.004), and the aforementioned VTE risk. For clarification, an OR measures association. It represents the odds that an outcome will occur in a group that shares some characteristic or exposure, compared to the odds of that event occurring in a group lacking the characteristic or exposure of interest. These ORs are followed closely by increases in the baseline incidence rates for the complications in question in our low- (n = 1396) vs high-risk groups (n = 398): infection (7.59% vs 13.57%), delayed wound healing (2.72% vs 5.78%), DVT (0.93% vs 3.77%), and general complication (26.93% vs 36.93%). Elucidated trends on infection corroborate previous work on infection that identified patient ASA-PS scores as independent predictors of postoperative morbidity and mortality. 7,34 Of greater concern for practitioners may be that our findings were deemed highly significant despite prophylactic antibiotic treatment for 82% of our patient cohort (n = 1794). In contrast, although Greco et al demonstrated significance between increasing ASA-PS scores and wound complication rates as well as increases in delayed wound

7 454 Aesthetic Surgery Journal 34(3) Table 8. Current American Society of Anesthesiologists Physical Status Classification Level Preoperative Health Status Comments and Examples 1 Normal healthy patient No organic, physiologic, or psychiatric disturbance; excludes the very young and very old; healthy with good exercise tolerance 2 Patients with mild systemic disease No functional limitations; has a well-controlled disease of one body system; controlled hypertension or diabetes without systemic effects, cigarette smoking without chronic obstructive pulmonary disease; mild obesity, pregnancy 3 Patients with severe systemic disease Some functional limitation; has a controlled disease of more than one body system or one major system; no immediate danger of death; controlled congestive heart failure, stable angina, old heart attack, poorly controlled hypertension, morbid obesity, chronic renal failure; bronchospastic disease with intermittent symptoms 4 Patients with severe systemic disease that is a constant threat to life 5 Moribund patients who are not expected to survive without the operation 6 A declared brain-dead patient whose organs are being removed for donor purposes healing, those findings were restricted to patients undergoing massive weight-loss surgery; these results may not translate to the greater patient population. 35 Similarly, support is sparse for or against the predictive power of ASA-PS scores in other complications. Previous studies support correlation of ASA scores with specific complications such as infection, 36 while other sources cite that ASA correlates best to general complications overall. 37 A contributing factor in this inability to successfully parse individual complications may be failure to include relevant outside factors when ASA-PS scores are calculated. OCP use, surgery length, and recent surgery were factors found in our study to have significant positive or negative associations with complications (Table 5), but these factors are not considered when ASA-PS scores are decided. As noted in Jeong et al, Caprini scores which do include those variables have been shown to successfully define a set of complications to which systemically compromised patients are more susceptible. 38 Interestingly, despite that the complications examined in this study (infection, dehiscence, erythema, necrosis, seroma, hematoma, delayed wound healing, or DVT) often correlate with age and BMI, they did not all correlate well with the ASA-PS, which is itself well correlated with these variables. 31 It should also be noted that the list of complications included for our study was comparatively exclusive. As Arvidsson et al noted, the ASA-PS system usually shows greatest correlation with cardiovascular complications because of its focus on physiologically vital functions, circulation and breathing, 37 neither of which are considered in our analysis. Also noteworthy was that our data did not demonstrate a significant difference in age between patients with complications and those without. Partly responsible may be the selfselective nature of plastic surgery patients. As a generally higher-income group with better access to health care, patients undergoing aesthetic operations may be able to compensate Has at least one severe disease that is poorly controlled or at end stage; possible risk of death; unstable angina, symptomatic chronic obstructive pulmonary disease, symptomatic congestive heart failure, hepatorenal failure Not expected to survive > 24 hr without surgery; imminent risk of death; multiorgan failure, sepsis syndrome with hemodynamic instability, hypothermia, poorly controlled coagulopathy for increasing age with better health maintenance, negating somewhat the detriments of senescence. Although this is an interesting statistical anomaly, we did not feel that it detracted from the ASA system s predictive power. Although age is often associated with risk classification, the ASA-PS does not include age in its categorization. If anything, we believe this produced better-controlled cohorts for analysis. The ASA-PS system has a unique ability to quickly and concisely summarize multiple patient characteristics. In addition, it can provide a numerical estimate of patient health status for standardization. Because of this, ASA-PS scores can play an important role in initial risk assessments. Despite concerns about scoring consistency among individual anesthesiologists, trends repeatedly demonstrate the ASA system s predictive power. Researchers have elicited those significances in spite of these consistency issues. That said, apart from emergency consultations where lack of patient cognizance can prevent clinicians from using more specific risk assessment methods, the ASA-PS classification is ill-suited as a long-term gauge of patient risk. While our data and other studies suggest utility of the ASA score in predicting complications, other accounts still question the reliability of the score itself. 4 As such, this information adds to the debate but is in no way definitive. Until some consensus is reached on which complications the ASA scores predict, they can at least help clinicians create a global risk assessment, and they should be used to screen patients for more comprehensive evaluation methods or when other methods are excluded, as in emergencies. Conclusions This study supports previous proposals to preoperatively apply the ASA-PS to categorize patient risk of developing postoperative complications. Patients with systemic issues

8 Miller et al 455 meriting higher ASA-PS scores are at increased risk of suffering complications primarily infection, delayed wound healing, and VTE events. According to our study, when all potential postoperative issues are considered, the high-risk patient has a 35% increase in odds of experiencing a complication compared with a low-risk individual. Our results also support efforts to separate patient risk outcomes into graded groups. This analysis is vital for preoperative decision making, especially with regard to prophylactic treatment. By dividing heterogeneous patient populations into groups with similar characteristics, standardized treatments for different risk categories can be devised. In the literature, inconsistency precludes us from recommending ASA-PS scores be used as a stand-alone risk assessment model outside the context of emergent, nonresponsive patients. Despite this, the ASA-PS system can initially gauge patient health in conjunction with other, more comprehensive risk assessment models. A multicenter or multispecialty study would expand the study population and validate our study s results, allowing for better clinical recommendations. Acknowledgments The authors would like to thank Roberto Cortez, Rachel Hein, Ryan Constantine, Kendall Anigian, James Jewell, Natalie Sciano, Bhavani Gannavarapu, Janeiro Okafor, and Allan Wang for compiling the original database. Additionally, we would like to thank Debby Noble and the research support team at University of Texas Southwestern for its invaluable efforts. Disclosures Dr Davis receives grants from ConvaTec (Skillman, New Jersey), Innovative Therapies (Pompano Beach, Florida), Unilever (Englewood Cliffs, New Jersey), Andrew Technologies (Tustin, California), and Kensey Nash (Exton, Pennsylvania). Dr Kenkel is an unpaid investigator for Allergan (Irvine, California) and Ultrashape (Synernon; Irvine, California) and serves as a paid member on the Advisory Board of Kythera (Calabasas, California) and Ulthera (Mesa, Arizona). The other authors have nothing to disclose. Funding The authors received no financial support for the research, authorship, and publication of this article. References 1. Saklad M. Grading of patients for surgical procedures. Anesthesiology 1941;2: Owens WD, Felts JA, Spitznagel EL Jr. ASA physical status classifications: a study of consistency of ratings. Anesthesiology 1978;49: Haynes SR, Lawler PGP. An assessment of the consistency of ASA physical status classification allocation. Anaesthesia 1995;50: Aronson WL, McAuliffe MS, Miller K. Variability in the American Society of Anesthesiologists Physical Status Classification Scale. AANA J 2003;71: Tiret L, Hatton F, Desmonts JM, Vourc h G. 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