Impact of Surgeon Demographics and Technique on Outcomes After Esophageal Resections: A Nationwide Study

Transcription

1 Impact of Surgeon Demographics and Technique on Outcomes After Esophageal Resections: A Nationwide Study Raja R. Gopaldas, MD, FACS, Castigliano M. Bhamidipati, DO, PhD, Tam K. Dao, PhD, and John G. Markley, MD Division of Cardiothoracic Surgery, Department of Surgery, University of Missouri-Columbia School of Medicine, Columbia, Missouri; Department of Surgery, State University of New York Upstate Medical University School of Medicine, Syracuse, New York; and Department of Biostatistics, University of Houston School of Medicine, Houston, Texas Background. Thoracic, cardiac, and general surgeons perform esophageal resections in the United States. This article examines the impact of surgeon subspecialty on outcomes after esophagectomy. Methods. Esophagectomies performed between 1998 and 2008 were identified in the Nationwide Inpatient Sample. Surgeons were classified as thoracic, cardiac, or general surgeons if greater than 65% of their operative case mix was representative of their specialty. Surgeons with less than 65% of a specialty-specific case mix served as controls. Regression equations calculated the independent effect of surgeon specialty, surgeon volume, and operative approach (transhiatal versus transthoracic) on outcomes. Results. Of the 40,589 patients who underwent esophagectomies, surgeon identifiers were available for 23,529 patients. Based on case mix, thoracic, cardiac, and general surgeons performed 3,027 (12.9%), 688 (2.9%), and 4,086 (17.4%) esophagectomies, respectively. Operative technique did not independently affect risk-adjusted outcomes mortality, morbidity, and failure to rescue (defined as death after a complication). Surgeon volume independently lowered mortality and failure to rescue by 4% (p < for both), but not complications (p 0.6). High-volume hospitals (>12 procedures/year) independently lowered mortality (adjusted odds ratio [AOR], 0.67, 95% confidence interval [CI], ), and failure to rescue (AOR, 0.64; 95% CI, ). Esophageal resections performed by general surgeons were associated with higher mortality (AOR, 1.87; 95% CI ) and failure to rescue (AOR, 1.95; 95% CI, ) but not complications (AOR, 0.97; 95% CI, ). Conclusions. General surgeons perform the major proportion of esophagectomies in the United States. Surgeon subspecialty is not associated with the risk of complications developing but instead is associated with mortality and failure to rescue from complications. Surgeon subspecialty case mix is an important determinant of outcomes for patients undergoing esophagectomy. (Ann Thorac Surg 2013;95:1064 9) 2013 by The Society of Thoracic Surgeons Surgeon specialty and training is presumed to affect outcomes in patients who undergo highly specialized and technically challenging procedures [1, 2], Studies have shown the impact of surgical specialty board certification to have both positive and negative associations with outcomes [3, 4]. Many hospitals do not use surgeon specialty certification during privileging and credentialing processes [5]. Nevertheless, emphasis has been placed on maintenance of certification as a means to assess the competence of surgeons after specialty training [6]. Some complex operations such as esophagectomies and open abdominal aortic aneurysm repair are performed both by general and specialized surgeons (ie, thoracic, nonthoracic cardiac, vascular diplomats) despite an era of increased specialization. Surgeon specialty certification has conferred lower mortality in patients undergoing esophagectomies for esophageal cancer or elective repair of an abdominal aneurysm [1, 7]. However, in esophageal operations, higher case volume has compensated for lack of specialty training [7, 8] Review of Medicare patients by Dimick et al [7, 8] did not account for the impact of relevant thoracic surgery specialty case mix. Collectively, it is unclear if outcomes after esophagectomy depend on the level of training, surgical procedure volume, or case mix of the surgeon in practice. With increased scrutiny of surgical outcomes, nonpatient factors (ie, hospital, surgeon) that impact morbidity and mortality have become equally important. In particular, the concept of failure to rescue, in which quality of surgical intervention depends on the ability of hospitals and physi- Accepted for publication Oct 16, Address correspondence to Dr Gopaldas, Division of Cardiothoracic Surgery, Department of Surgery, University of Missouri-Columbia School of Medicine, Ste MA 312, One Hospital Dr, Columbia, MO 65212; gopaldasr@health.missouri.edu. Dr Gopaldas discloses a financial relationship with Cardioptimus LLC by The Society of Thoracic Surgeons /$36.00 Published by Elsevier Inc

2 Ann Thorac Surg GOPALDAS ET AL 2013;95: ESOPHAGEAL RESECTIONS: A POPULATION-BASED ANALYSIS 1065 cians to prevent morbidity from translating into mortality, has gained popularity among surgical patients [9, 10]. Based on these observations, we sought to determine the impact of surgeon case mix on the outcomes of patients undergoing esophageal resection from a nationwide perspective. Material and Methods Data Source Data was abstracted from the Nationwide Inpatient Sample (NIS) from 1998 through The NIS is a database assimilated from 1,000 hospitals with approximately 8 million annual hospitalizations maintained by the Agency for Healthcare Research and Quality (AHRQ) as part of the Healthcare Cost and Utilization Project [11]. Being the largest all-payer database, it represents 20% of all hospital discharges from nonfederal facilities in the United States. AHRQ and the Healthcare Cost and Utilization Project validate the NIS annually by comparing the data with the National Hospital Discharge Survey and the Medicare Provider Analysis and Review. Given the deidentified nature of this study, it was exempt by the Institutional Review Board of the University of Missouri- Columbia School of Medicine. Patient Selection We used International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) procedure codes to query annual datasets and identify all patients who underwent esophageal resections from 1998 through The ICD-9-CM procedure codes 42.4, 42.41, 42.42, 42.5, and were used to select patients who underwent esophagectomy. The procedures were categorized as transthoracic or transhiatal type based on the presence of an intrathoracic anastomosis identified by the specific procedure codes. Patient Characteristics The Deyo comorbidity index [12], which has been demonstrated to be an improvement on the Charlson comorbidity index, was used to compare preoperative morbidity and stratify risk in the study sample [13]. The Deyo index uses more than 600 ICD-9-CM diagnosis codes to query specific comorbid diagnoses. Patient comorbidities were identified from each patient s ICD-9-CM diagnosis codes recorded in the NIS dataset. These codes were then summarized into a comorbidity score for each patient. Surgeon and Hospital Characteristics The Clinical Classification Software (CCS) provided by AHRQ permits stratification of the primary procedure into the appropriate clinical category. CCS-Services and Procedures provide a method for classifying Current Procedural Terminology (CPT) codes into clinically meaningful procedure categories. More than 9,000 CPT and 6,000 Healthcare Common Procedure Coding System codes are collapsed into 244 clinically meaningful categories (CCS) [14]. Using these specific CCS procedure categories, surgeons were categorized as thoracic, cardiac, and general surgeons (Appendix). Using the entire dataset for a particular year, the association between procedural categories for patients who underwent esophagectomy was examined by the encrypted surgeon identifier for each separate year. To ensure that physicians were categorized correctly, the associations were analyzed annually. An a priori threshold of 65% of any given case mix in a particular specialty was used to designate surgeons (ie, thoracic, cardiac, or general). A fourth category of surgeons included those who did not satisfy the cutoff threshold of 65%, and they were designated as unclassified, serving as the control group for analyses. Separately, based on the literature, centers were dichotomized into low or high volume using a threshold of 12 esophagectomies performed per year [15]. Study Outcomes The outcomes of this study were rates of in-hospital mortality, risk of a complication developing, and failure to rescue (defined as a mortality that occurred in the event of a complication). All-cause in-hospital complications were recorded according to ICD-9-CM diagnosis codes. Complications were further categorized based on clinical relevance. Statistical Analysis Wald 2 tests examined the association of categorical variables with surgical approach and surgeon type. Single-factor analysis of variance models examined continuous data by surgical approach and surgeon type. Multivariable regression models examined the risk-adjusted association, including surgical approach, surgeon type, and hospital and surgeon volume, with outcomes. Computations were completed using SPSS, version 19.0 (IBM Corp, Armonk, NY). Results Patient Demographics and Characteristics We were able to identify 23,529 patients who underwent esophagectomy for whom surgeon identifiers were available. Surgeons whose case mix did not exceed the chosen threshold value to designate them as a particular category performed 66.8% of the esophagectomies. Patients (Tables 1, 2) in whom the transhiatal approach was used had slightly higher comorbidity scores. Less than 15% of all esophagectomies were performed by thoracic or cardiac surgeons. A higher proportion of transhiatal esophagectomies were performed in teaching hospitals. Although more than half of the operations were performed at low-volume hospitals, the proportion of transhiatal operations compared with operations performed with a transthoracic approach was marginally higher at highvolume hospitals (47.7% versus 46.4%). Mortality Unadjusted mortality was 7.6% and was not influenced by type of surgical approach (Table 3). Unadjusted mortality was lowest for thoracic surgeons (4.8%) and highest for cardiac (14.2%) surgeons (Table 4). However after adjustment, there was no impact by a thoracic or cardiac

3 1066 GOPALDAS ET AL Ann Thorac Surg ESOPHAGEAL RESECTIONS: A POPULATION-BASED ANALYSIS 2013;95: Table 1. Patient Demographics and Admission Characteristics by Surgical Approach Transhiatal n 14,935 Transthoracic n 8,593 Age, y Female 3,393 (22.7%) 1,858 (21.6%) 0.05 Elective 12,537 (83.9%) 7,161 (83.3%) 0.22 Deyo comorbidity index Primary payer 6,867 (46.0%) 4,015 (46.7%) 0.01 Medicare Teaching hospital 11,720 (78.5%) 6,328 (73.6%) High-volume hospital 7,127 (47.7%) 3,983 (46.4%) 0.05 Surgeon, thoracic 2,015 (13.5%) 1,011 (11.8%) 0.01 Surgeon, cardiac 432 (2.9%) 256 (3.0%) Surgeon, general 2,725 (18.2%) 1,361 (15.8%) Shown as mean standard deviation or count and proportion. surgeon on mortality, whereas general surgeons were independently associated with an 87% increase in the adjusted odds of mortality. Other factors that independently affected mortality were hospital volume (adjusted odds ratio [AOR], 0.67; 95% confidence interval [CI], ) and individual surgeon case volume (AOR, 0.96; 95% CI, ). Teaching status of the hospital or surgical approach did not independently influence mortality. Morbidity Overall morbidity after esophagectomy was 68.1%. Transthoracic esophagectomy had a significantly higher incidence of overall morbidity (p 0.001). Gastrointestinal complications, which predominantly included anastomotic complications, were higher in the transthoracic group (p 0.001) (Table 3). After risk adjustment, surgeon specialty case mix, case volume, teaching status of the hospital, and hospital volume were not independently associated with increased morbidity (Table 4). Failure to Rescue Cumulative failure to rescue was 7.1%. Regression models demonstrated that increasing age, female sex, nonelective operations, low hospital volume, low surgeon volume, and case mix independently increased the adjusted odds of failure to rescue. Female sex and Table 3. Unadjusted Outcomes by Surgical Approach case mix increased the adjusted odds of failure to rescue by 51% and 95%, respectively (Table 5). Surgeons with a predominantly thoracic or cardiac case mix did not independently increase the odds of failure to rescue, whereas general surgeons did, supporting the premise that involvement in the operative aspects of esophagectomy only partially explains the overall outcome in patients. Comment Transhiatal n 14,935 Transthoracic n 8,593 Mortality 1, % % 0.74 Morbidity Gastrointestinal/leaks 1, % 1, % Operative 1, % % 0.01 Deep vein thrombosis % % 0.76 Infections 2, % 1, % 0.04 Respiratory 6, % 3, % Transfusions 2, % 1, % 0.03 Thoracic duct % % 0.12 Any complication 10, % 5, % Failure to rescue 1, % % 0.67 Routine home discharge 6, % 3, % Shown as count and proportion. Despite attempts to improve quality, esophagectomy remains associated with considerable morbidity and mortality [16, 17]. The relationships between surgeon and hospital procedure volume and outcomes after esophagectomy have been reported and have evolved to quality benchmarks [1, 7, 8]. Outcomes after esophageal resection are thus influenced both by patient characteristics and nonpatient factors [18, 19].The current study examines the association between practice pattern strata and mortality, morbidity, and failure to rescue. Not surprisingly, surgeons who perform the majority of esophagectomies in the United States are neither thoracic nor cardiac subspecialty surgeons. Schipper and associates [20] stratified discharge records from patients who underwent pulmonary resection by practice pattern case mix, categorizing the surgeon by proportion of type of operation performed, and reported Table 2. Patient Demographics and Admission Characteristics by Surgeon Case Mix Control n 15,728 Thoracic n 3,026 Cardiac n 688 General n 4,086 Age, y Female sex 3,451 (21.9%) 769 (25.4%) 176 (25.6%) 854 (20.9%) Elective operation 12,935 (82.2%) 2,671 (88.2%) 550 (79.9%) 3,542 (86.7%) Deyo index Primary payer Medicare 7,469 (47.6%) 1,217 (40.2%) 315 (45.9%) 1,880 (46.0%) Teaching hospital 11,617 (73.9%) 2,768 (91.4%) 465 (67.6%) 3,199 (78.3%) High-volume hospital 6,846 (43.5%) 2,131 (70.4%) 120 (17.4%) 2,013 (49.3%) Shown as mean standard deviation or count and proportion.

4 Ann Thorac Surg GOPALDAS ET AL 2013;95: ESOPHAGEAL RESECTIONS: A POPULATION-BASED ANALYSIS 1067 Table 4. Unadjusted Outcomes by Surgeon Case Mix Control n 15,728 Thoracic n 3,026 Cardiac n 688 General n 4,086 Mortality 8.2% 4.7% 13.7% 6.7% Morbidity Gastrointestinal 10.8% 10.9% 11.5% 9.7% 0.19 Operative 10.1% 8.7% 17.4% 11.7% Deep vein thrombosis 0.7% 1.0% % 0.10 Infections 15.5% 16.1% 20.1% 16.7% Respiratory 43.5% 40.8% 50.4% 45.1% Transfusions 16.9% 20.5% 22.1% 15.6% Thoracic duct 1.9% 2.9% % All (total) 68.2% 68.0% 70.1% 66.9% 0.29 Failure to rescue 7.6% 3.7% 12.9% 6.4% Routine home discharge 39.2% 46.2% 34.2% 49.3% conceptually similar results. Thematically consistent with their findings, we demonstrate a strong relationship between outcomes and the type of surgeon performing esophageal operations. Thoracic surgeons and cardiac surgeons achieve mortality outcomes that are superior to those of general surgeons, and differences in the failure to rescue patients after operation are significantly impacted by surgeon subspecialty experience, rather than the incidence of complications itself. Our definitions of thoracic, cardiac, and general surgeons was based on the practice pattern case mix in a particular year and not on board certification an issue that could be subject to critique. Because the NIS codes each surgeon with a unique anonymous identifier, it is not possible to identify individual surgeons and link with the American Board of Thoracic Surgery (ABTS) certification repository. Neither is it possible to track surgeons over time because of the deidentified nature of data. Although ABTS certification differentiates between cardiothoracic and general surgeons [7], it does not discern between general thoracic and cardiac surgeons. This may be possible in the near future given that surgeons certified by ABTS after mid-2007 are designated into 2 tracks. However none of this is available on nationwide databases yet. When considering the additional complexity added by surgeons who complete thoracic fellowships after ABTS certification, our methodology in stratifying surgeons by the proportion of their case mix and then determining calculations is putatively superior. We used an arbitrary threshold of 65% to delineate individual surgeon s subspecialty practice. Albeit arbitrary, there are no data in the literature to support a case volume based premise to stratify providers. Our conservative estimate reasonably assumes appropriate representation of the predominant practice pattern of a surgeon if two thirds of case volume is pertinent to the specialty. Based on our stratification, the control group included surgeons whose practice pattern was homogenously distributed across procedures among the 3 comparison cohorts (thoracic, cardiac, and general). Adjusted mortality was markedly higher after esophagectomy performed by general surgeons. In addition, although morbidity was equivalent, the failure to rescue rate was much higher among general surgeons. Taken together these data suggest Table 5. Adjusted Mortality, Morbidity, and Failure to Rescue Models Mortality Morbidity Failure to Rescue AOR AOR AOR Age, y Female sex White Surgeon volume Elective versus urgent Teaching versus nonteaching hospital High- versus low-volume hospital Transthoracic versus transhiatal Subspecialty versus control Thoracic Cardiac General AOR adjusted odds ratio.

5 1068 GOPALDAS ET AL Ann Thorac Surg ESOPHAGEAL RESECTIONS: A POPULATION-BASED ANALYSIS 2013;95: that surgeons with a more specialized case mix (ie, thoracic or cardiac) are possibly better at recognizing esophagectomyrelated complications early. Furthermore, these data provide preliminary evidence that surgeons with a limited subspecialty case mix are technically adept at performing esophagectomy, but the ability to identify, treat, and mitigate aspects of this highly morbid operation may be limited. Consistent with other studies, we also found that surgical approach did not independently influence mortality, morbidity, or failure to rescue [21 24]. Our results are also congruent with results from previous studies [21, 25] demonstrating that esophagectomies performed at high-volume hospitals significantly reduced the odds of death. In addition, we extend the notion that high-volume esophagectomy centers confer protection for patients [21, 25] by providing evidence that failure to rescue rates were 33% better at high-volume hospitals. Together these data suggest that esophagectomy performed at high-volume centers is associated with improved ability to intervene in the event of a complication to avoid mortality. The administrative nature of the analyzed dataset has limitations that should be considered in the interpretation of our results. The NIS database does not provide detailed clinical information, which may help determine if early signs of complications were missed or if there was a delay in recognizing a complication. Long-term outcomes cannot be studied either. Patients readmitted after discharge cannot be tracked in the national edition of the database. Similarly, long-term mortality, recurrence of cancer, and survival rates are unknown. Further, physician identifiers were specific only for each calendar year, preventing simulation analysis for the arbitrary cutoff points to be performed, as this would have to be done separately for each year. This would make interpreting the data complex and impractical, as it would preclude the data sample from being treated as a single entity. In summary, we conclude that general surgeons perform the majority of esophagectomies in the United States. Surgeon specialty case mix did not influence complication rates but significantly affected failure to rescue after a complication and consequently mortality. Complications after esophagectomy are handled more effectively when these operations are performed by surgeons whose practice pattern is predominantly thoracic or cardiac and are less likely to result in mortality. In the broader context, in addition to individual surgeon and hospital volume, subspecialty specific case mix pattern also influences the overall outcomes for patients undergoing esophagectomy and should become a consideration in complex surgical procedures. References 1. Dimick JB, Cowan JA, Jr, Stanley JC, et al. Surgeon specialty and provider volumes are related to outcome of intact abdominal aortic aneurysm repair in the United States. J Vasc Surg 2003;38: Goodney PP, Lucas FL, Stukel TA, Birkmeyer JD. Surgeon specialty and operative mortality with lung resection. Ann Surg 2005;241: Grosch EN. Does specialty board certification influence clinical outcomes? J Eval Clin Pract 2006;12: Sharp LK, Bashook PG, Lipsky MS, Horowitz SD, Miller SH. Specialty board certification and clinical outcomes: the missing link. Acad Med 2002;77: Freed GL, Dunham KM, Singer D. Use of board certification and recertification in hospital privileging: policies for general surgeons, surgical specialists, and nonsurgical subspecialists. Arch Surg 2009;144: Bower EA, Choi D, Becker TM, Girard DE. Awareness of and participation in maintenance of professional certification: a prospective study. J Contin Educ Health Prof 2007;27: Dimick JB, Goodney PP, Orringer MB, Birkmeyer JD. Specialty training and mortality after esophageal cancer resection. Ann Thorac Surg 2005;80: Dimick JB, Wainess RM, Upchurch GR, Jr, Iannettoni MD, Orringer MB. National trends in outcomes for esophageal resection. Ann Thorac Surg 2005;79:212 6; discussion Ghaferi AA, Birkmeyer JD, Dimick JB. Hospital volume and failure to rescue with high-risk surgery. Med Care 2011;49: Ghaferi AA, Birkmeyer JD, Dimick JB. Complications, failure to rescue, and mortality with major inpatient surgery in medicare patients. Ann Surg 2009;250: Nationwide Inpatient Sample. Healthcare Cost and Utilization Project, Available at: Accessed December 5, Deyo RA CD, Ciol MA. Adapting a clinical comorbidity index for use with ICD-9-CM administrative databases. J Clin Epidemiol 1992;45: Cherkin DC, Deyo RA, Volinn E, Loeser JD. Use of the International Classification of Diseases (ICD-9-CM) to identify hospitalizations for mechanical low back problems in administrative databases. Spine (Phila Pa 1976) 1992;17: Clinical Classifications Software (CCS) for ICD-9-CM. Available at: CCSUsersGuide.pdf. Accessed: April 12, Varghese TK, Jr., Wood DE, Farjah F, et al. Variation in esophagectomy outcomes in hospitals meeting leapfrog volume outcome standards. Ann Thorac Surg 2011;91:1003 9; discussion Blencowe NS, Strong S, McNair AG, et al. Reporting of short-term clinical outcomes after esophagectomy: a systematic review. Ann Surg 2012;255: Orringer MB, Marshall B, Chang AC, et al. Two thousand transhiatal esophagectomies: changing trends, lessons learned. Ann Surg 2007;246:363 72; discussion Markar SR, Karthikesalingam A, Thrumurthy S, Low DE. Volume-outcome relationship in surgery for esophageal malignancy: systematic review and meta-analysis J Gastrointest Surg 2011;16: Al-Refaie WB, Muluneh B, Zhong W, et al. Who receives their complex cancer surgery at low-volume hospitals? J Am Coll Surg 2012;214: Schipper PH, Diggs BS, Ungerleider RM, Welke KF. The influence of surgeon specialty on outcomes in general thoracic surgery: a national sample 1996 to Ann Thorac Surg 2009;88: ; discussion Chang AC, Ji H, Birkmeyer NJ, Orringer MB, Birkmeyer JD. Outcomes after transhiatal and transthoracic esophagectomy for cancer. Ann Thorac Surg 2008;85: Colvin H, Dunning J, Khan OA. Transthoracic versus transhiatal esophagectomy for distal esophageal cancer: which is superior? Interact Cardiovasc Thorac Surg 2011;12: Barreto JC, Posner MC. Transhiatal versus transthoracic esophagectomy for esophageal cancer. World J Gastroenterol 2010;16: Pac M, Basoglu A, Kocak H, et al. Transhiatal versus transthoracic esophagectomy for esophageal cancer. J Thorac Cardiovasc Surg 1993;106: Chang AC, Birkmeyer JD. The volume-performance relationship in esophagectomy. Thorac Surg Clin 2006;16:87 94.

6 Ann Thorac Surg GOPALDAS ET AL 2013;95: ESOPHAGEAL RESECTIONS: A POPULATION-BASED ANALYSIS 1069 Appendix CCS Procedures Codes for Designating Procedure Category Volume Case Mix CCS-ICD-9-CM Procedure or Service Thoracic 36 Lobectomy or pneumonectomy 37 Diagnostic bronchoscopy and biopsy of bronchus 38 Other diagnostic procedures on lung and bronchus 39 Incision of pleura, thoracentesis, chest drainage 40 Other diagnostic procedures of respiratory tract and mediastinum 42 Other operating room (OR) therapeutic procedures on respiratory system Cardiac 43 Heart valve procedures 44 Coronary artery bypass graft (CABG) 49 Other OR heart procedures 50 Extracorporeal circulation auxiliary to open heart procedures General Surgery 10 Thyroidectomy, partial or complete 66 Procedures on spleen 71 Gastrostomy, temporary and permanent 72 Colostomy, temporary and permanent (Continued) Appendix (Continued). CCS-ICD-9-CM Procedure or Service 73 Ileostomy and other enterostomy 74 Gastrectomy, partial and total 75 Small bowel resection 76 Colonoscopy and biopsy 78 Colorectal resection 79 Local excision of large intestine lesion (not endoscopic) 80 Appendectomy 81 Hemorrhoid procedures 83 Biopsy of liver 84 Cholecystectomy and common duct exploration 85 Inguinal and femoral hernia repair 86 Other hernia repair 87 Laparoscopy 89 Exploratory laparotomy 90 Excision, lysis peritoneal adhesions 91 Peritoneal dialysis 94 Other OR upper gastrointestinal (GI) therapeutic procedures 96 Other OR lower GI therapeutic procedures 99 Other OR gastrointestinal therapeutic procedures CCS Clinical Classification Software; CM Clinical Modification; ICD International Classification of Diseases.