Influence of Perioperative COVID-19 Infection on Surgical Outcomes and Risk Adjustment for Quality Assessment in the American College of Surgeons NSQIP.

BACKGROUND: Surgical patients with perioperative coronavirus disease 19 (COVID-19) infection experience higher rates of adverse events than those without COVID-19, which may lead to imprecision in hospital-level quality assessment. Our objectives were to quantify differences in COVID-19-associated adverse events in a large national sample and examine distortions in surgical quality benchmarking if COVID-19 status is not considered. STUDY DESIGN: Data included 793,280 patient records from the American College of Surgeons NSQIP from April 1, 2020, to March 31, 2021. Models predicting 30-day mortality, morbidity, pneumonia, and ventilator dependency greater than 48 hours, and unplanned intubation were constructed. Risk adjustment variables were selected for these models from standard NSQIP predictors and perioperative COVID-19 status. RESULTS: A total of 5,878 (0.66%) had preoperative COVID-19, and 5,215 (0.58%) had postoperative COVID-19. COVID-19 rates demonstrated some consistency across hospitals (median preoperative 0.84%, interquartile range 0.14% to 0.84%; median postoperative 0.50%, interquartile range 0.24% to 0.78%). Postoperative COVID-19 was always associated with increased adverse events. For postoperative COVID-19 among all cases, there was nearly a 6-fold increase in mortality (1.07% to 6.37%) and15-fold increase in pneumonia (0.92% to 13.57%), excluding the diagnosis of COVID-19 itself. The effects of preoperative COVID-19 were less consistent. Inclusion of COVID-19 in risk-adjustment models had minimal effects on surgical quality assessments. CONCLUSIONS: Perioperative COVID-19 was associated with a dramatic increase in adverse events. However, quality benchmarking was minimally affected. This may be the result of low overall COVID-19 rates or balance in rates established across hospitals during the 1-year observational period. There remains limited evidence for restructuring ACS NSQIP risk-adjustment for the time-limited effects of the COVID-19 pandemic.

NSQIP Quality Benchmarking and Evaluation of Potential Bias Associated with Higher- or Lower-Risk Operation Case Mix.

BACKGROUND: To ensure validity and acceptance of NSQIP risk-adjusted benchmarking, it is important that adjustments adequately control for hospitals that vary in their proportions of lower- or higher-risk operations (combined risk for procedure and patient). This issue was addressed in separate empirical and simulation studies. STUDY DESIGN: For the empirical study, potential miscalibration bias favoring hospitals that do lower-risk operations or disfavoring hospitals that do higher-risk operations was evaluated for 14 modeled outcomes using NSQIP data. A determination was also made as to whether there was a relationship between mean hospital operation risk and benchmarking results (log odds ratio). In the simulation study of the same 14 outcomes, hospital benchmarked performance was evaluated when sampled cases were reconstituted to include either a larger proportion of lower-risk operations or a larger proportion of higher-risk operations. RESULTS: Miscalibration favoring either lower- or higher-risk operations was absent, as were important associations between operative risk and hospital log odds ratios (most model R 2 less than 0.01). In the simulation, there were no substantial changes in log odds ratios when greater percentages of either lower- or higher-risk operations were included in a hospital's sample (nonsignificant p values and effect sizes less than 0.1). CONCLUSIONS: These results should enhance NSQIP participants' confidence in the adequacy of NSQIP patient and procedure risk-adjustment methods. NSQIP participants may rely on benchmarking findings, and implement quality improvement efforts based on them, without concern that they are biased by a preponderance of lower or higher risk operations.

Postoperative Complications and Hospital Payment: Implications for Achieving Value.

BACKGROUND: As the current healthcare structure moves toward value-based purchasing, it is helpful for stakeholders to understand costs, particularly for those associated with postoperative complications. The objectives of this study were to assess hospital reimbursements for postoperative complications and generate insight into sustainability of quality. STUDY DESIGN: American College of Surgeons NSQIP and Medicare claims data from 2009 to 2012 were merged for elective colectomy, total knee arthroplasty, and carotid endarterectomy. Payments associated with 7 postoperative complications across each operation were estimated from multivariable regression models. The impact on hospital marginal costs was estimated from the regression results by accounting for complication incidence rates. RESULTS: Mean hospital payments per uncomplicated procedure were approximately $13,500 for colectomy (n = 19,089), $12,300 for total knee arthroplasty (n = 17,834), and $7,300 for carotid endarterectomy (n = 16,207). The payment amount per complication increased at a rate of $10,996 for colectomy, $13,732 for total knee arthroplasty, and $8,435 for carotid endarterectomy. When distinguishing between types of complications, the most expensive complication was prolonged ventilation, increasing mean payment by approximately $14,100 (colectomy) and $6,700 (carotid endarterectomy), respectively. Hospital marginal costs accounting for complication rates added additional amounts ranging from 0.82% to 9.2%. CONCLUSIONS: Postoperative complications add an important marginal cost to Medicare payments, and lead to a substantial portion of payments to hospitals. Using high-quality clinical registry data to measure complication rates, we estimated the cost of complications for 3 commonly performed operations among the Medicare population. Harmonizing financial incentives for both payers and providers are needed to improve the delivery of high-quality surgical care.

Development and Evaluation of the American College of Surgeons NSQIP Pediatric Surgical Risk Calculator.

BACKGROUND: There is an increased desire among patients and families to be involved in the surgical decision-making process. A surgeon's ability to provide patients and families with patient-specific estimates of postoperative complications is critical for shared decision making and informed consent. Surgeons can also use patient-specific risk estimates to decide whether or not to operate and what options to offer patients. Our objective was to develop and evaluate a publicly available risk estimation tool that would cover many common pediatric surgical procedures across all specialties. STUDY DESIGN: American College of Surgeons NSQIP Pediatric standardized data from 67 hospitals were used to develop a risk estimation tool. Surgeons enter 18 preoperative variables (demographics, comorbidities, procedure) that are used in a logistic regression model to predict 9 postoperative outcomes. A surgeon adjustment score is also incorporated to adjust for any additional risk not accounted for in the 18 risk factors. RESULTS: A pediatric surgical risk calculator was developed based on 181,353 cases covering 382 CPT codes across all specialties. It had excellent discrimination for mortality (c-statistic = 0.98), morbidity (c-statistic = 0.81), and 7 additional complications (c-statistic > 0.77). The Hosmer-Lemeshow statistic and graphic representations also showed excellent calibration. CONCLUSIONS: The ACS NSQIP Pediatric Surgical Risk Calculator was developed using standardized and audited multi-institutional data from the ACS NSQIP Pediatric, and it provides empirically derived, patient-specific postoperative risks. It can be used as a tool in the shared decision-making process by providing clinicians, families, and patients with useful information for many of the most common operations performed on pediatric patients in the US.

Association of the 2011 ACGME Resident Duty Hour Reform with Postoperative Patient Outcomes in Surgical Specialties.

BACKGROUND: The 2011 ACGME resident duty hour reform implemented additional restrictions to existing duty hour policies. Our objective was to determine the association between this reform and patient outcomes among several surgical specialties. STUDY DESIGN: Patients from 5 surgical specialties (neurosurgery, obstetrics/gynecology, orthopaedic surgery, urology, and vascular surgery) were identified from the American College of Surgeons NSQIP. Data from 1 year before and 2 years after the reform was implemented were obtained for teaching and nonteaching hospitals. Hospital teaching status was defined based on the percentage of operations with a resident present intraoperatively. Difference-in-differences models were developed separately for each specialty and adjusted for patient demographics, comorbidities, procedural case-mix, and time trends. The association between duty hour reform and a composite measure of death or serious morbidity within 30 days of surgery was estimated for each specialty. RESULTS: The unadjusted rate of death or serious morbidity decreased during the study period in both teaching and nonteaching hospitals for all surgical specialties. In multivariable analyses, there were no significant associations between duty hour reform and the composite outcomes of death or serious morbidity in the 2 years post-reform for any surgical specialty evaluated (neurosurgery: odds ratio [OR] = 0.90; 95% CI, 0.75-1.08; p = 0.26; obstetrics/gynecology: OR = 0.96; 95% CI, 0.71-1.30; p = 0.80; orthopaedic surgery: OR = 0.95; 95% CI, 0.74-1.22; p = 0.70; urology: OR = 1.16; 95% CI, 0.89-1.51; p = 0.26; vascular surgery: OR = 1.07; 95% CI, 0.93-1.22; p = 0.35). CONCLUSIONS: Implementation of the 2011 ACGME resident duty hour reform was not associated with a significant change in patient outcomes for several surgical specialties in the 2 years after reform.

Risk of discharge to postacute care: a patient-centered outcome for the american college of surgeons national surgical quality improvement program surgical risk calculator.

IMPORTANCE: Individualized risk prediction tools have an important role as decision aids for use by patients and surgeons before surgery. Patient-centered outcomes should be incorporated into such tools to widen their appeal and improve their usability. OBJECTIVE: To develop a patient-centered outcome for the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) Surgical Risk Calculator, a web-based, individualized risk prediction tool. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study using data from the ACS NSQIP, a national clinical data registry. A total of 973 211 patients from July 2010 to June 2012, encompassing 392 hospitals, were used in this analysis. MAIN OUTCOMES AND MEASURES: Risk of discharge to a postacute care setting. RESULTS: The overall rate of discharge to postacute care was 8.8%. Significant predictors of discharge to postacute care included being 85 years or older (odds ratio [OR] = 9.17; 95% CI, 8.84-9.50), the presence of septic shock (OR = 2.43; 95% CI, 2.20-2.69) or ventilator dependence (OR = 2.81; 95% CI, 2.56-3.09) preoperatively, American Society of Anesthesiologists class of 4 or 5 (OR = 3.59; 95% CI, 3.46-3.71), and totally dependent functional status (OR = 2.27; 95% CI, 2.11-2.44). The final model predicted risk of discharge to postacute care with excellent accuracy (C statistic = 0.924) and calibration (Brier score = 0.05). CONCLUSIONS AND RELEVANCE: Individualized risk of discharge to postacute care can be predicted with excellent accuracy. This outcome will be incorporated into the ACS NSQIP Surgical Risk Calculator.

Impact of hepatectomy surgical complexity on outcomes and hospital quality rankings.

BACKGROUND: There is substantial variation in the surgical complexity of hepatectomy. Currently, the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) risk adjusts for hospital quality comparisons using only the primary procedure code. Our objectives were to (1) assess the association between secondary procedures and complications; (2) assess model performance with inclusion of surgical complexity adjustment; and (3) examine whether secondary procedures affect hospital quality rankings. METHODS: Using ACS NSQIP (2007-2012), patients undergoing hepatectomy were identified. Secondary procedure codes and total work relative value units (RVUs) were used to approximate procedural complexity. The effect of procedural complexity variables on outcomes and hospital quality rankings were examined using hierarchical models. RESULTS: Among 11,826 patients who underwent hepatectomy at 261 hospitals, 32.8 % underwent at least one secondary procedure. Serious morbidity occurred in 18.0 % of patients. Seven of nine secondary procedures were significantly associated with death or serious morbidity on multivariable analysis. Model performance improved when secondary procedure categories were included, and secondary procedure categories outperformed total RVUs. The C-statistic for death or serious morbidity was 0.689 in the standard NSQIP model, 0.703 when total RVU was included, and 0.718 when secondary procedure categories were included. Of the 26 hospitals that were poor performers for death or serious morbidity using the standard ACS NSQIP model, three became average performers when secondary procedure categories were included in the model. CONCLUSIONS: Secondary procedures are associated with an increased risk of postoperative complications. Inclusion of secondary procedure code categories in research and risk prediction models should be considered for hepatectomy.

Variation in quality of care after emergency general surgery procedures in the elderly.

BACKGROUND: The elderly (age ≥65 years) comprise an increasing proportion of patients undergoing emergency general surgery (EGS) procedures and have distinct needs compared with the young. We postulated that the needs of the elderly require different processes of care than those required for the young to assure optimal outcomes. To explore this hypothesis, we evaluated 30-day outcomes following EGS procedures in the young and the elderly and determined whether hospital performance was consistent across these 2 age strata. STUDY DESIGN: With data from the American College of Surgeons National Surgical Quality Improvement Program (2005 to 2008), regression models were constructed for serious morbidity and mortality for all patients undergoing EGS procedures and separately for young and elderly patients. These models allowed for estimation of the risk of adverse outcomes associated with advanced age and the generation of hospital-level observed to expected (O/E) ratios. We evaluated the correlation between hospital O/E ratios for the young and the elderly and the concordance of outlier status (hospitals with CIs of O/E ratios excluding 1) with weighted κ across these 2 age groups. RESULTS: Among 68,003 procedures at 186 hospitals, elderly patients had a higher crude and adjusted risk for serious morbidity (27.9% versus 9.7%, p < 0.0001; odds ratio 1.17, 95% CI 1.10 to 1.24) and mortality (15.2% versus 2.5%, p < 0.0001; odds ratio 2.29, 95% CI 2.09 to 2.51). When outcomes for elderly versus younger patients were compared, there was fair to moderate agreement on hospital performance for serious morbidity (r = 0.43; κ = 0.30) but not for mortality (r = 0.10; κ = 0.17). CONCLUSIONS: Elderly patients are at substantially greater risk for adverse events following EGS procedures. Hospitals had only slight agreement in mortality outcomes in the elderly compared with those in young patients. Processes of care that may account for this disparity should be further investigated.

Pancreatectomy risk calculator: an ACS-NSQIP resource.

BACKGROUND: The morbidity of pancreatoduodenectomy remains high and the mortality may be significantly increased in high-risk patients. However, a method to predict post-operative adverse outcomes based on readily available clinical data has not been available. Therefore, the objective was to create a 'Pancreatectomy Risk Calculator' using the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database. METHODS: The 2005-2008 ACS-NSQIP data on 7571 patients undergoing proximal (n = 4621), distal (n = 2552) or total pancreatectomy (n = 177) as well as enucleation (n = 221) were analysed. Pre-operative variables (n = 31) were assessed for prediction of post-operative mortality, serious morbidity and overall morbidity using a logistic regression model. Statistically significant variables were ranked and weighted to create a common set of predictors for risk models for all three outcomes. RESULTS: Twenty pre-operative variables were statistically significant predictors of post-operative mortality (2.5%), serious morbidity (21%) or overall morbidity (32%). Ten out of 20 significant pre-operative variables were employed to produce the three mortality and morbidity risk models. The risk factors included age, gender, obesity, sepsis, functional status, American Society of Anesthesiologists (ASA) class, coronary heart disease, dyspnoea, bleeding disorder and extent of surgery. CONCLUSION: The ACS-NSQIP 'Pancreatectomy Risk Calculator' employs 10 easily assessable clinical parameters to assist patients and surgeons in making an informed decision regarding the risks and benefits of undergoing pancreatic resection. A risk calculator based on this prototype will become available in the future as on online ACS-NSQIP resource.

Improving American College of Surgeons National Surgical Quality Improvement Program risk adjustment: incorporation of a novel procedure risk score.

BACKGROUND: Risk-adjusted evaluation is a key component of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP). The purpose of this study was to improve standard ACS NSQIP risk adjustment using a novel procedure risk score. STUDY DESIGN: Current Procedural Terminology codes (CPTs) represented in ACS NSQIP data were assigned to 136 procedure groups. Log odds predicted risk from preliminary logistic regression modeling generated a continuous risk score for each procedure group, used in subsequent modeling. Appropriate subsets of 271,368 patients in the 2008 ACS NSQIP were evaluated using logistic models for overall 30-day morbidity, 30-day mortality, and surgical site infection (SSI). Models were compared when including either work Relative Value Unit (RVU), RVU and the standard ACS NSQIP CPT range variable (CPT range), or RVU and the newly constructed CPT risk score (CPT risk), plus routine ACS NSQIP predictors. RESULTS: When comparing the CPT risk models with the CPT range models for morbidity in the overall general and vascular surgery dataset, CPT risk models provided better discrimination through higher c statistics at earlier steps (0.81 by step 3 vs 0.81 by step 46), more information through lower Akaike's information criterion (127,139 vs 130,019), and improved calibration through a smaller Hosmer-Lemeshow chi-square statistic (48.76 vs 116.79). Improved model characteristics of CPT risk over CPT range were most apparent for broader patient populations and outcomes. The CPT risk and standard CPT range models were moderately consistent in identification of outliers as well as assignment of hospitals to quality deciles (weighted kappa ≥ 0.870). CONCLUSIONS: Information from focused, clinically meaningful CPT procedure groups improves the risk estimation of ACS NSQIP models.

A current profile and assessment of north american cholecystectomy: results from the american college of surgeons national surgical quality improvement program.

BACKGROUND: Cholecystectomy is among the most common surgical procedures performed in the United States. The current state of cholecystectomy outcomes, including variations in hospital performance, is unclear. The objective of this study is to compare the risk factors, indications, and 30-day outcomes, as well as variations in hospital performance associated with laparoscopic (LC) versus open cholecystectomy (OC) at 221 hospitals during a 4-year period. STUDY DESIGN: Using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database (2005-2008), patients were identified who underwent cholecystectomy and related procedures (cholangiogram and/or common bile duct exploration). Four outcomes were studied, ie, 30-day overall morbidity, serious morbidity, surgical site infections, and mortality. Forward stepwise logistic regressions yielded patient-level predicted probabilities, and hospital-level observed-to-expected ratios were determined. RESULTS: Of 65,511 patients, 58,659 (89.5%) underwent LC; 6,852 (10.5%) underwent OC. OC patients were considerably older with a higher comorbidity burden. LC patients were less likely to experience any morbidity (3.1% versus 17.8%; p < 0.0001), a serious morbidity (1.4% versus 11.1%; p < 0.0001), or a surgical site infection (1.3% versus 8.4%; p < 0.0001), and less likely to die (0.3% versus 2.8%; p < 0.0001). Observed-to-expected ratios for overall morbidity ranged from 0 to 3.55; for serious morbidity, 0 to 3.23; for surgical site infection, 0 to 7.02; for mortality, 0 to 13.05. CONCLUSIONS: Although overall incidence of adverse events is low after LC, substantial morbidity and mortality are associated with OC. Additionally, controlling for patient- and operation-related factors, considerable variations exist in hospital performance when evaluating 30-day outcomes after cholecystectomy.

Does hospital type affect pyloromyotomy outcomes? Analysis of the Kids' Inpatient Database.

BACKGROUND: Pyloromyotomy is a common operative procedure performed on infants. The purpose of this study was to determine if hospital type affects lengths of stay (LOS), charges, and morbidity. METHODS: Patients undergoing pyloromyotomy were identified in the Kids' Inpatients Database from 2000, 2003, and 2006. Freestanding children's hospitals (CH) were compared with children's units within general hospitals (CUGH) and general/nonchildren's hospitals (GH). RESULTS: Of the 10,969 patients, 25% received care at 30 CH, 35% received care at 94 CUGH, and 40% received care at 662 GH. Adjusted LOS were 2.41 days for CH, 2.75 days for CUGH, and 2.82 days for GH (P < .01). Adjusted mean charges were $11,160 for CH, $12,284 for CUGH, and $10,197 for GH (P = .01). CH had the lowest unadjusted complication rate at 1.2% compared with 1.6% at CUGH and 2.2% at GH (P < .01). GH were more likely to have patients with prolonged LOS (> or =4 days) compared with CH after adjusting for patient and hospital factors (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.2-2.5). After accounting for LOS, CUGH were more likely to have higher charges (> or =$11,057) compared with CH (OR, 3.4; 95% CI, 1.03-11.18). The adjusted mean charges rose from $7,733 in 2000 to $11,335 in 2003 and to $14,572 in 2006 (P < .01). CONCLUSION: CH had the shortest LOS and lowest complication rates. Despite a higher complication rate and longer LOS, GH had the lowest charges. There is an opportunity to identify best practices, to improve quality, and to lower costs for pyloromyotomy in the United States, regardless of hospital type.

Comparison of pulmonary function in immigrant vs US-born Asian Indians.

OBJECTIVE: This study investigated whether there is a difference in pulmonary function between healthy adult US-born Asian Indians and immigrant Asian Indians attributable to country of birth, environmental, and socioeconomic factors. DESIGN: FEV(1), FVC, and forced mid-expiratory flow between 25% and 75% of vital capacity (FEF(25-75)) were measured in India-born and US-born subjects residing in the Chicago metropolitan area. Hollingshead Index of Social Position was used to evaluate socioeconomic factors. RESULTS: There were 262 India-born (61.8% male), and 200 US-born (50% male) subjects who were healthy lifelong nonsmokers; their age range was 16 to 36 years. US-born Asian Indian men and women were taller and had higher pulmonary function values for height and age compared with immigrant Asian Indian men and women. The differences were most pronounced in women: about 7% for FVC, 9% for FEV(1), and 17% for FEF(25-75). Immigrant and US-born subjects did not differ in socioeconomic position. CONCLUSION: We conclude that US-born Asian Indian men and women have higher pulmonary function values for age and height compared with immigrant Asian Indian men and women. This probably reflects the effect of differing environmental conditions, which cause year-of-birth trends in lung volumes.

Variability in length of stay after colorectal surgery: assessment of 182 hospitals in the national surgical quality improvement program.

BACKGROUND: Length of postoperative stay (LOS) has gained increasing attention as a potential indicator of surgical efficiency. Our objective was to examine the feasibility of assessing LOS at 182 hospitals to identify institutions with outlying performance. METHODS: Patients were identified who underwent colorectal surgery at 182 hospitals participating in the American College of Surgeon's National Surgical Quality Improvement Program (ACS NSQIP) from 2006 to 2007. Regression models for extended LOS (greater than the 75th percentile) were developed to identify hospitals whose ratios of observed to expected events (O/E) were significantly better (low outlier) or worse (high outlier) than expected after adjustment for case mix. To evaluate strategies for evaluating LOS that would be minimally influenced by the occurrence of complications, separate models were developed for patients categorized either by (1) the nonoccurrence or occurrence of any postoperative complication or (2) tercile of preoperative morbidity risk. RESULTS: The 23,098 patients selected for this study were partitioned into groups without complications (0% complications), with complications (100%) or into terciles of preoperative morbidity risk (with 22.4%, 38.7%, and 60.0% of patients having complications, respectively). In general, the greater the complication rate the longer the LOS and the fewer the number of statistical outliers that were identified. CONCLUSIONS: ACS NSQIP data can provide individual hospitals with riskadjusted LOS measures that can be used to identify outlying performance and motivate quality improvement efforts.

Variability in reoperation rates at 182 hospitals: a potential target for quality improvement.

BACKGROUND: Reoperation rate has gained increasing attention as a potential indicator of surgical quality. Objectives of this study were to examine the feasibility of assessing reoperation rates at 182 hospitals to identify institutions with outlying performance, to examine potentially modifiable factors that are associated with reoperations, and to determine if a more parsimonious logistic regression model effectively predicts reoperations. STUDY DESIGN: Patients were identified who underwent colorectal procedures at 182 hospitals participating in the American College of Surgeon's National Surgical Quality Improvement Program in 2006-2007. Risk-adjusted regression models for reoperation were developed to identify hospitals that had ratios of observed-to-expected events that were substantial outliers. RESULTS: Of 23,098 patients identified, 1,320 (5.7%) required reoperations. Reoperation occurred significantly more often than expected in 16 hospitals and less often than expected in 7 hospitals (p < 0.05). Factors that were associated with an increased risk of reoperation were advanced American Society of Anesthesiologists class, male gender, contaminated wounds, surgical extent, surgical indication, smoking, poor functional status, disseminated cancer, COPD, steroid dependence, anemia, body mass index (calculated as kg/m(2)) >35 or < or = 18.5, and hypertension. Compared with the full logistic regression model, there was a high degree of correlation with the more parsimonious logistic model containing only the first six variables (r = 0.996). CONCLUSIONS: There is considerable variability in reoperation rates at American College of Surgeon's National Surgical Quality Improvement Program hospitals. American College of Surgeon's National Surgical Quality Improvement Program data can be used to provide individual hospitals with risk-adjusted self-assessment data on reoperations to potentially identify quality-improvement opportunities.

Effect of subjective preoperative variables on risk-adjusted assessment of hospital morbidity and mortality.

OBJECTIVE: To examine the influence of American Society of Anesthesiologists Physical Status Classification (ASA) and preoperative Functional Health Status (FHS) variables on risk-adjusted estimates of surgical quality and to assess whether classifications are inflated at some hospitals. BACKGROUND: ASA and FHS are influential in risk-adjusted comparisons of surgical quality. However, because ASA and FHS are subjective they can be inflated, making patients appear more ill than they actually are, and crediting hospitals for a sicker patient population. METHODS: We identified 28,751 colorectal surgery patients at 170 hospitals participating in the American College of Surgeon's National Surgical Quality Improvement Program (ACS NSQIP) during 2006 to 2007. Logistic regression models were developed for morbidity and mortality with and without inclusion of ASA and FHS. Hospital quality rankings from the different models were compared. RESULTS: Morbidity and mortality rates were 24.3% and 3.9%, respectively. Percents of patients in ASA classes I through V were 3.3%, 46.4%, 41.5%,8.3%, and 0.7% and that were independent or partially or totally dependent were 89.2%, 7.2%, and 3.6%, respectively. Models that included ASA and FHS exhibited slightly better fit (Hosmer-Lemshow statistic) and discrimination(c-statistic) than models without both these variables, though magnitudes of differences were consistent with chance. There was inconsistent evidence for improper assignment of ASA and FHS. CONCLUSIONS: The small improvements in model quality when both ASA and FHS are present versus absent, suggest that they make a unique contribution to assessing severity of preoperative risk. With little indication that these subjective variables are subject to an important level of institutional bias, it is appropriate that they be used to assess risk-adjusted surgical quality. Periodic monitoring for inappropriate inflation of ASA status is warranted.