SURGERY: The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org. To take the CME activity related to this article, you must have either an STS member or an individual non-member subscription to the journal. Impact of Hospital Volume of Thoracoscopic Lobectomy on Primary Lung Cancer Outcomes Henry S. Park, BS, Frank C. Detterbeck, MD, Daniel J. Boffa, MD, and Anthony W. Kim, MD Section of Thoracic Surgery, Yale University School of Medicine, New Haven, Connecticut Background. This study evaluated hospital operative volume of video-assisted thoracoscopic surgery (VATS) lobectomy in primary lung cancer as a predictor of short-term outcomes after pulmonary lobectomy on a national scale. Some previous analyses comparing VATS vs open lobectomy outcomes have been limited by inaccuracies in patient cohort identification. Methods. The 2008 Healthcare Utilization Project- Nationwide Inpatient Sample database was culled using the International Classification of Diseases (9th Clinical Modification) procedure codes specifically distinguishing VATS vs open lobectomies (32.41 and 32.49, respectively) available only after October 2007. High hospital VATS volume was defined as 95th percentile or higher (> 20 VATS/year). Univariable and multivariable analyses were used to identify independent predictors of the following outcome measures: 30-day in-hospital morbidity and mortality, hospital length of stay (LOS), and hospital costs. Results. We identified 6,292 primary lung cancer patients undergoing pulmonary lobectomy, including 1,523 undergoing VATS (24%). Compared with open, VATS patients had fewer complications (38% vs 44%, p < 0.001) and median LOS (5 vs 7 days; p < 0.001). In multivariable analysis, VATS was an independent predictor of fewer total complications (odds ratio, 0.83; p 0.004) and shorter LOS (2.3 0.3-day difference, p < 0.001). Patients undergoing VATS at high-volume VATS hospitals had shorter median LOS (4 vs 6 days, p 0.001) compared with low-volume VATS hospitals. Multivariable analysis showed high hospital VATS volume independently predicted shorter LOS (0.9 0.4-day difference, p 0.001). Conclusions. In a national database, VATS lobectomy was associated with fewer complications and shorter LOS than open lobectomy in primary lung cancer patients. Among patients undergoing VATS, high hospital volume was also associated with shorter LOS. (Ann Thorac Surg 2012;93:372 80) 2012 by The Society of Thoracic Surgeons Interest in minimally invasive surgical interventions, including video-assisted thoracoscopic surgery (VATS), has grown steadily since the first report of VATS lobectomy for lung cancer in 1994 [1]. This procedure was initially controversial, however, due to concerns about inferior oncologic results. Multiple studies have since supported the long-term oncologic equivalence and perioperative benefit in complications, hospital length of stay (LOS), and costs of VATS compared with conventional open thoracotomy, particularly after it was demonstrated that VATS could be performed without rib spreading [2 7]. The primary criticism of these studies is that these comparisons were made at single-institution, high-volume centers of excellence in VATS. Given the lack of a large prospective, randomized trial comparing VATS vs open lobectomy and the low likelihood of such a trial being performed in the future, a population-based comparison of perioperative clinical and economic outcomes is needed. Two previous analyses were published by two independent groups in 2010 using a national inpatient database [8, 9], but Accepted for publication June 14, 2011. Address correspondence to Dr Kim, Yale University School of Medicine, Section of Thoracic Surgery, 330 Cedar St, BB 205, New Haven, CT 06520; e-mail: anthony.kim@yale.edu. both studies used incorrect procedure codes to identify the VATS vs open lobectomy cohorts, thus limiting the ability to draw any conclusion from these studies. Another important question for a population-based comparison of VATS lobectomy is the role of hospital volume on perioperative and oncologic outcomes. In 2001 Bach and colleagues [10] published a seminal study demonstrating that on a national scale, patients with stage I to IIIA non-small cell lung cancer resected at high-volume hospitals had fewer postoperative complications, a lower 30-day mortality rate, and increased 5-year survival than similar patients treated at low-volume hospitals. Several other reports since then have shown a positive association between increased hospital volume and improved patient outcomes after several other types of high-risk cardiothoracic operations, including coronary artery bypass grafting, aortic valve replacement, and esophagectomy [11 13]. To date, the effect of hospital volume on outcomes for lung cancer patients specifically after VATS lobectomy is unknown. The aims of this population-based analysis were (1) to compare perioperative clinical and economic outcomes after VATS vs open lobectomy using accurate procedure codes, and (2) among patients undergoing VATS, to compare perioperative clinical and economic outcomes after VATS at high-volume vs low-volume hospitals. 2012 by The Society of Thoracic Surgeons 0003-4975/$36.00 Published by Elsevier Inc doi:10.1016/j.athoracsur.2011.06.054
Ann Thorac Surg PARK ET AL 2012;93:372 80 HOSPITAL VOLUME AND VATS LUNG LOBECTOMY Material and Methods Data Source This study is a retrospective cohort analysis of 2008 hospital discharge information from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample (HCUP-NIS) database, which is maintained by the Agency for Healthcare Research and Quality. HCUP-NIS is the largest all-payer inpatient database publicly available in the United States (U.S.). It contains data on more than 8 million hospital stays annually from more than 1,000 hospitals and approximates a 20% stratified sample of all U.S. nonfederal hospitals. Weights based on sampling probabilities for each stratum are used in the analysis to ensure that the hospitals studied are representative of all U.S. hospitals. This study was granted exemption from Institutional Review Board approval at our institution, because HCUP-NIS is a public database with no personal identifying information. Patient Selection Criteria Procedure codes are based on the International Classification of Diseases, 9th edition, Clinical Modification (ICD-9-CM), Volume 3, which was created by the National Center for Health Statistics (NCHS) as an extension of the ICD-9 classification initially published in 1977 by the World Health Organization (WHO). All changes and modifications to the ICD-9-CM are overseen by the NCHS and the Center for Medicare and Medicaid Services. Before October 2007, lung lobectomy was coded nonspecifically with ICM-9-CM procedure code 32.4, but beginning in October 2007, this code was replaced by two new codes specifying thoracoscopic (32.41) vs all other surgical approaches (32.49) to lung lobectomy. We chose 2008 was chosen because it was the only full calendar year in which the new codes were used and that was available in the HCUP-NIS at the time of the study. Patients undergoing redo thoracotomy, indicated by ICD-9-CM procedure code 34.03, were excluded. Independent Variables The primary independent variables, surgical technique (VATS vs open) and hospital VATS volume, were modeled as categoric variables. Hospitals were designated as high-volume VATS centers if they were in the 95th percentile if more than 20 VATS were performed there per year and as high-proportion VATS centers if their VATS/total lobectomy ratio exceeded 50%. Independent patient demographic variables included age, sex, race, median household income, and primary payer, defined as private/health Maintenance Organization, Medicaid, self-pay, Medicare, no charge, and other. Categories for median household income were $1 to $38,999 (low), $39,000 to $47,999 (medium-low), $48,000 to $63,000 (medium), and more than $63,000 (high). Comorbidity scores were calculated using an adaptation of the Charlson Comorbidity Index [14]. Because all patients in our cohort had a minimum Charlson score of 2 due to their diagnoses of primary lung cancer, Charlson 373 scores of 2 to 3 were categorized as low, 4 to 5 as medium, and 6 or more as high. Other hospital-provider variables included hospital region (Northeast, Midwest, South, and West), location (urban and rural), and teaching status (teaching and nonteaching). All independent variables were treated as categoric variables. Outcome Variables The outcomes of interest were (1) in-hospital total and pulmonary complications, (2) mean LOS, (3) total inpatient hospital charges, and (4) in-hospital death. Perioperative complications were categorized as woundrelated, infectious, cardiovascular, intraoperative, systemic, gastrointestinal, urinary, and pulmonary (adapted from the Appendix in Gopaldas and colleagues [8]). Information regarding complication severity was not available, so complications were treated as a dichotomous variable (0 vs 1). Statistical Analysis Univariable analyses of the independent variables with our outcomes of interest were performed by 2 statistical analysis to compare proportions of total complications and pulmonary complications, and by Mann-Whitney nonparametric analysis to compare medians of LOS and costs. Multivariable logistic regression models were used to adjust for independent variables for in-hospital total and pulmonary complications, and multivariable linear regression models were used to adjust for significant independent variables for LOS and total in-patient hospital costs. These analyses were adjusted for demographic and clinical patient and provider distributions. A backward elimination procedure was applied for independent variable selection. Reference comparisons were selected according to standard procedure for the HCUP database. Data analysis and management were performed using SPSS 16.0 software (SPSS Inc, Chicago, IL) and Excel 2007 (Microsoft Corp, Redmond, WA). All tests were two-sided, with statistical significance set at a value of p 0.05. Results VATS vs Open Lobectomy The 2008 HCUP-NIS database identified 6,292 lobectomies for patients with primary lung cancer, including 1,523 (24%) with VATS and 4,769 with open. The patients were a median age of 67 years, 52% were women, 87% were white, and most were treated in urban teaching hospitals. VATS was significantly more common than open lobectomy in patients who were women, had a high median household income, had a low comorbidity score, and were treated in an urban teaching hospital in the Northeast (Table 1). There was no difference by age, race, or primary payer. Patients undergoing VATS lobectomy had fewer total complications (38% vs 44%, p 0.001) and shorter median LOS (5 vs 7 days, p 0.001) than those undergoing
374 PARK ET AL Ann Thorac Surg HOSPITAL VOLUME AND VATS LUNG LOBECTOMY 2012;93:372 80 Table 1. Patient and Provider Characteristics of All Patients Undergoing Lobectomy Characteristics All, % VATS, % Open, % (N 6,292) (n 1,523) (n 4,769) p Value Patient variables Age 65 years 63.9 66.0 63.3 0.057 Female sex 52.1 56.7 50.6 0.001 Race White a 86.6 86.1 86.8 0.51 Black 6.3 6.2 6.3 Hispanic 3.2 3.6 3.0 Other 4.0 4.2 3.9 Median household income Low 22.9 19.0 24.1 0.001 Medium-low 28.7 23.8 30.2 Medium 23.9 24.5 23.7 High a 24.6 32.7 22.0 Private HMO a 31.4 32.5 31.0 0.30 Medicare 60.4 61.4 60.0 Medicaid 4.6 3.2 5.1 Other 3.6 2.9 3.9 Low a 44.8 47.3 44.0 0.024 Medium 26.6 26.4 26.7 High 28.6 26.3 29.3 Hospital variables Region Northeast a 20.4 34.5 15.9 0.001 Midwest 23.0 14.6 25.7 South 39.0 33.9 40.6 West 17.6 16.9 17.8 Urban hospital 94.8 97.6 93.9 0.001 Teaching hospital 58.1 66.6 55.3 0.001 a Reference comparison. b Comorbidity was assessed by the Charlson Comorbidity Index. HMO health maintenance organization; open lobectomy (Table 2). Adjustments for patient and provider characteristics in multivariable analysis showed VATS was an independent predictor of fewer total complications (odds ratio [OR], 0.83; p 0.004) and shorter LOS (2.3 0.3-day difference, p 0.001) compared with open (Table 3). High vs Low VATS Volume Among the 1,523 patients undergoing VATS lobectomy, the median age was 68 years, 57% were women, 86% were white, and most patients were treated in urban teaching hospitals. High-volume hospitals tended to be urban teaching hospitals in the Northeast and were used significantly more frequently than low-volume hospitals by high-income patients (Table 4). There was no significant difference by age, sex, race, primary payer, or comorbidity score. Patients undergoing VATS at high-volume hospitals had a shorter median LOS (4 vs 6 days, p 0.001) than those at low-volume hospitals, and patients undergoing VATS at high-proportion hospitals had fewer complications (34.3% vs 42.1%, p 0.002) and shorter median LOS (5 vs 7 days, p 0.001) than those at low-proportion hospitals (Table 5). Adjusting for patient and provider characteristics in multivariable analysis showed high hospital VATS volume was an independent predictor of shorter LOS (0.9 0.4-day difference, p 0.004) compared with low hospital VATS volume, and high hospital VATS proportion was an independent predictor of fewer complications (OR, 1.39; p 0.002) and shorter LOS (0.8 0.4-day difference, p 0.043) compared with low hospital VATS proportion (Table 6). Similar results were noted when hospitals in the 90th percentile ( 11 VATS per year) were included as high-volume hospitals compared with when hospitals in the 95th percentile ( 20 VATS per year) were defined as such.
Ann Thorac Surg PARK ET AL 2012;93:372 80 HOSPITAL VOLUME AND VATS LUNG LOBECTOMY Table 2. Unadjusted Outcomes of All Patients Undergoing Lobectomy (N 6,292) Characteristic Total Complications Length of Stay Costs Mortality % p Value Days (median) p Value $ (median) p Value % p Value 375 Patient variables Age, years 64 39.0 0.001 6 0.001 19,251 0.001 1.1 0.001 65 44.1 7 20,806 2.6 Male 45.8 0.001 7 0.001 21,084 0.001 2.6 0.001 Female 39.0 6 19,453 1.5 Race White a 42.3 0.060 6 0.001 19,752 0.004 2.0 0.77 Black 38.6 7 20,331 0.9 Hispanic 34.0 6 21,552 1.9 Other 41.7 6 21,651 2.9 Median household income Low 43.7 0.30 7 0.001 19,244 0.044 2.5 0.47 Medium-low 42.2 7 19,502 2.0 Medium 42.1 7 21,242 1.9 High a 41.1 6 21,120 1.8 Private HMO a 37.8 0.001 6 0.001 18,811 0.001 1.3 0.007 Medicare 44.8 7 20,900 2.4 Medicaid 46.0 7 22,154 1.7 Other 34.5 7 18,980 2.2 Low a 40.1 0.002 6 0.001 19,249 0.001 1.6 0.019 Medium 45.2 7 20,619 2.6 High 42.9 7 21,360 2.3 Surgical technique VATS 38.3 0.001 5 0.001 19,656 0.16 1.5 0.12 Open 43.5 7 20,348 2.2 Hospital variables Region Northeast a 41.1 0.34 6 0.001 22,592 0.001 1.6 0.22 Midwest 45.0 7 20,347 2.1 South 41.1 7 17,365 2.2 West 42.7 6 28,481 2.3 Location Urban 40.6 0.56 7 0.20 20,270 0.022 2.2 0.84 Rural 42.3 7 18,472 2.0 Teaching status Teaching 43.2 0.21 6 0.001 20,559 0.019 2.0 0.79 Nonteaching 41.6 7 19,725 2.1 a Reference comparison. b Comorbidity was assessed by the Charlson Comorbidity Index. HMO health maintenance organization; Comment In the first part of our study, our findings of decreased short-term morbidity and shorter hospital LOS among lung cancer patients undergoing VATS lobectomy compared with those undergoing open lobectomy are consistent with the results of previous smaller studies [2 7]. According to a 2009 review [15], most studies have agreed that VATS lobectomy is at least oncologically equivalent to open lobectomy at up to 5 years of follow-up [2, 3] and may also have biologic benefits due to a decreased inflammatory response and less postoperative reduction in immune function [16].
376 PARK ET AL Ann Thorac Surg HOSPITAL VOLUME AND VATS LUNG LOBECTOMY 2012;93:372 80 Table 3. Independent Predictors of Outcomes for All Patients (N 6,292) Explanatory Variables a Results p Value Total complications Odds ratio (95% CI) Female 0.78 (0.70 to 0.87) 0.001 Non-HMO 1.40 (1.24 to 1.59) 0.001 Medium 1.15 (1.02 to 1.31) 0.026 Surgical technique VATS 0.83 (0.73 to 0.94) 0.004 Length of stay c (95% CI), days Female 0.87 ( 1.34 to 0.40) 0.001 Median household 0.70 (0.16 to 1.24) 0.011 income Low Non-HMO 1.27 (0.77 to 1.78) 0.001 Surgical technique VATS 2.33 ( 2.87 to 1.79) 0.001 Costs c (95% CI), $ Female 2,912 ( 4,265 to 1,558) 0.001 Non-HMO 3,514 (2,044 to 4,984) 0.001 High 2,052 (435 to 3,669) 0.013 Hospital region Midwest 4,699 ( 6,990 to 2,408) 0.001 South 5,566 ( 7,396 to 3,736) 0.001 West 9,374 (7,172 to 11,577) 0.001 Hospital teaching status Nonteaching 2,193 ( 3,597 to 789) 0.002 Mortality Odds Ratio (95% CI) Age, years 65 2.41 (1.54 to 3.78) 0.001 Female 0.61 (0.42 to 0.87) 0.006 a Reference comparisons were age 65, male sex, white race, high income, private HMO insurance, open surgical technique, low Charlson comorbidity, Northeast region, urban hospital location, and teaching hospital status. b Comorbidity was assessed by the Charlson Comorbidity Index. c is the linear regression coefficient, indicating the numeric difference in outcome (in specified units) between explanatory variable and reference comparison. CI confidence interval; HMO health maintenance organization; Perioperatively, open lobectomy has been reported to have a complication rate of 32% to 37%, according to the prospective American College of Surgeons Oncology Group Z0030 clinical trial of 766 patients [17] and a retrospective analysis of The Society of Thoracic Surgeons database of 6,042 patients [18]. For VATS lobectomy, the prospective Cancer and Leukemia Group B 39802 clinical trial of 127 patients reported major perioperative (grade 3) morbidity in only 7% of patients, although total perioperative morbidity was not reported [8]. When VATS and open lobectomy were compared in a small prospective study of 55 patients, total complications were significantly less frequent when VATS was used as the initial approach [5]. These results have been supported by other recent studies [6, 7], including a propensity-matched analysis from The Society of Thoracic Surgeons database [19]. Two other studies attempting to compare VATS vs open lobectomy using the HCUP-NIS database identified patients in the two cohorts with incorrect procedure codes [8, 9]. Because the procedure codes distinguishing VATS lobectomy from open lobectomy only began to be used in October 2007, the study periods of 2004 and 2006 by Gopaldas and colleagues [8] that compared diagnostic transpleural thoracoscopy vs nonspecific lobectomy and 2007 by Hannan and colleagues [9] that compared VATS lobectomy vs nonspecific lobectomy (the latter of which also includes VATS patients from January to September 2007) were too early to perform this analysis using the HCUP-NIS database. Therefore, our study period of 2008 was the first full year available to analyze this comparison during these data. We believe that our findings have more face validity than those of Gopaldas and colleagues [8] and Hannan and colleagues [9] because our reported rates of VATS lobectomy are more consistent with those previously reported in the literature (24% vs 5% and 7%, respectively). Of note, men with Medicare or Medicaid insurance had consistently worse perioperative outcomes overall, even after multivariable adjustment of demographic and clinical factors such as age, income, and comorbidity. Although unavailable covariates, such as tumor stage, may play a strong role, this represents a curious finding that may be multifactorial in etiology. In addition, the variability in inpatient LOS and costs across different geographic regions of the United States may be influenced by a variety of factors not measured in the database, including but not limited to differences in billing practices, expenses of perioperative staff and resources, and attitudes of patients and providers regarding discharge variables. In the second part of our study, among the 1,523 VATS patients, patients who underwent VATS at hospitals with high annual VATS volume ( 20 VATS per year) had a significantly shorter hospital LOS than those at hospitals with low annual VATS volume, but had equivalent total hospital costs and short-term rates of morbidity and mortality. Interestingly, patients at hospitals that used VATS for most of their annual lung cancer lobectomies had both fewer complications and shorter hospital LOS than those at hospitals with a low ratio of VATS to total lobectomy. Using VATS proportion rather than VATS volume as a
Ann Thorac Surg PARK ET AL 2012;93:372 80 HOSPITAL VOLUME AND VATS LUNG LOBECTOMY Table 4. Characteristics of Video-Assisted Thoracoscopic Patients (N 1,523) Characteristic All, % (N 1,523) Low, % (n 801) High, % (n 722) p Value Patient variables Age 65 66.0 65.7 66.3 0.79 Female sex 56.7 55.3 58.3 0.26 Race White a 86.1 84.7 87.5 0.16 Black 6.2 7.9 4.4 Hispanic 3.6 2.3 4.9 Other 4.2 5.1 3.2 Median household income Low 19.0 22.3 15.5 0.001 Medium-low 23.8 27.2 20.0 Medium 24.5 24.4 24.6 High a 32.7 26.1 39.9 Private HMO a 32.5 30.5 34.7 0.089 Medicare 61.4 62.0 60.7 Medicaid 3.2 3.4 3.1 Other 2.9 4.1 1.5 Low a 47.3 46.2 48.5 0.38 Medium 26.4 26.6 26.2 High 26.3 27.2 25.3 Hospital variables Region Northeast a 34.5 22.2 48.2 0.001 Midwest 14.6 17.6 11.4 South 33.9 39.7 27.6 West 16.9 20.5 12.9 Urban hospital 97.6 95.5 100.0 0.001 Teaching hospital 66.6 56.3 78.1 0.001 377 a Reference comparison. b Comorbidity was assessed by the Charlson Comorbidity Index. HMO health maintenance organization. proxy for experience may reflect a decrease in case selection bias, because surgeons at hospitals with mature VATS programs may be less inclined to avoid using VATS for high-risk patients. For lung cancer operations overall, hospital volume has been shown to be associated with both short-term morbidity and long-term mortality rates on a national scale [10]. There may also be other provider-related factors involved in lung cancer operations. Recent evidence from HCUP-NIS suggests that in-hospital lung cancer deaths may be reduced in teaching hospitals compared with nonteaching hospitals at all but the highest volume institutions [20] and that general Table 5. Unadjusted Outcomes of Video-Assisted Thoracoscopic Surgery Patients (N 1,523) Hospital Variable Total Complications Length of Stay Costs Mortality % p Value Days (median) p Value $ (median) p Value % p Value VATS volume Low 38.5 0.92 6 0.001 19,558 0.60 1.6 0.83 High 38.1 4 19,905 1.4 VATS proportion Low 42.1 0.002 7 0.001 20,034 0.76 1.3 0.53 High 34.3 5 20,675 1.7
378 PARK ET AL Ann Thorac Surg HOSPITAL VOLUME AND VATS LUNG LOBECTOMY 2012;93:372 80 Table 6. Independent Predictors of Outcomes for Video- Assisted Thoracoscopic Surgery Patients (N 1,523) Explanatory Variables a Odds Ratio (95% CI) p Value Total complications Age, years 65 1.43 (1.15 to 1.79) 0.002 Hospital VATS proportion High 1.39 ( 1.72 to 1.13) 0.002 Length of stay b (95% CI), days Median household income Low 1.43 (0.66 to 2.20) 0.001 Non-HMO 1.81 (1.04 to 2.58) 0.001 Hospital VATS volume High 0.90 ( 1.67 to 0.13) 0.022 Hospital VATS proportion High 0.79 ( 1.55 to 0.02) 0.043 Costs b (95% CI), $ Non-HMO 4,876 (1,938 to 7,814) 0.001 Hospital region West 13,057 (9,194 to 16,921) 0.001 Hospital teaching status Non-teaching 6,035 ( 8,877 to 3,193) 0.001 Mortality Odds Ratio (95% CI) Age 65 4.73 (1.09 to 20.53) 0.038 Race Non-white 2.82 (1.07 to 7.47) 0.037 a Reference comparisons were age 65 years, male sex, white race, high income, private HMO insurance, low Charlson comorbidity, Northeast region, urban hospital location, teaching hospital status, low hospital VATS volume, and low hospital VATS proportion. b is linear regression coefficient, indicating the numeric difference in outcome (in specified units) between explanatory variable and reference comparison. CI confidence interval; HMO health maintenance organization; thoracic surgeons may achieve better mortality rates and hospital LOS outcomes after decortications, segmentectomies, lobectomies, and pneumonectomies than surgeons not specializing in cardiothoracic surgery [21]. The provider-related covariates that we examined, including hospital geography, urban vs rural location, and teaching status, appeared to have minimal effect on in-hospital morbidity and mortality rates among VATS patients specifically. The limitations of this study include those inherent to any retrospective analysis of a large administrative database, although HCUP-NIS is widely used and has been well validated. Some degree of treatment selection bias is possible in the VATS vs open cohorts and the highvolume vs low-volume cohorts. However, the available demographic and clinical characteristics that could have potentially confounded the results of this study were adjusted for in multivariable analysis, which can isolate the independent predictors of outcomes. Long-term outcomes cannot be assessed from the database, and readmissions are not captured; thus, the observed complication rates may be underestimated. The hospital LOS was recorded as the date of admission to the date of discharge because the date of the operation was not recorded; thus, specific postoperative LOS could not be ascertained. However, most lobectomies are performed as same-day admissions, so it is likely that only a small number of patients were actually hospitalized before the operation. Other potential modifying factors not captured by the database include number of years in practice, surgeon specialty or board certification, cumulative surgeon or hospital experience with thoracoscopic or open lobectomy, and pathologic characteristics and staging of the lung cancers. In conclusion, our study has demonstrated, on a national scale, that VATS lobectomy is independently associated with fewer total complications and shorter LOS for patients with primary lung cancer compared with open lobectomy. For patients undergoing VATS lobectomy, high hospital VATS volume is also associated with shorter LOS, whereas a high hospital VATS/total lobectomy ratio is associated with fewer total complications and shorter LOS. Although this type of retrospective analysis has the potential for selection bias, the findings of this population-based study are largely consistent with other published studies and support the notion that VATS is a reasonable and perhaps preferred approach for lung cancer lobectomy given the benefit in short-term morbidity and hospital LOS stay and equivalence in total hospital costs and short-term mortality. In addition, experienced VATS centers may also be recommended given a similar benefit in short-term morbidity and hospital LOS. As the national experience with VATS and the subsequent collection of VATS-specific data increases, further research will be necessary to validate this study. H.S. Park was partly supported by the James G. Hirsch, M.D. Endowed Medical Student Research Fellowship, Yale University School of Medicine. References 1. McKenna RJ Jr. Lobectomy by video-assisted thoracic surgery with mediastinal node sampling for lung cancer. J Thorac Cardiovasc Surg 1994;107:879 82. 2. Sugi K, Kaneda Y, Esato K. Video-assisted thoracoscopic lobectomy achieves a satisfactory long-term prognosis in patients with clinical stage IA lung cancer. World J Surg 2000;24:27 31. 3. Yan TD, Black D, Bannon PG, McCaughan BC. Systematic review and meta-analysis of randomized and nonrandomized trials on safety and efficacy of video-assisted thoracic
Ann Thorac Surg PARK ET AL 2012;93:372 80 HOSPITAL VOLUME AND VATS LUNG LOBECTOMY surgery lobectomy for early-stage non-small-cell lung cancer. J Clin Oncol 2009;27:2553 62. 4. Kirby TJ, Mack MJ, Landreneau RJ, Rice TW. Lobectomy video-assisted thoracic surgery versus muscle-sparing thoracotomy. A randomized trial. J Thorac Cardiovasc Surg 1995;109:997 1002. 5. Villamizar NR, Darrabie MD, Burfeind WR, et al. Thoracoscopic lobectomy is associated with lower morbidity compared with thoracotomy. J Thorac Cardiovasc Surg 2009;138: 419 25. 6. Flores RM, Park BJ, Dycoco J, et al. Lobectomy by videoassisted thoracic surgery (VATS) versus thoracotomy for lung cancer. J Thorac Cardiovasc Surg 2009;138:11 8. 7. Swanson SJ, Herndon JE 2nd, D Amico TA, et al. Videoassisted thoracic surgery lobectomy: report of CALGB 39802 a prospective, multi-institution feasibility study. J Clin Oncol 2007;25:4993 7. 8. Gopaldas RR, Bakaeen FG, Dao TK, Walsh GL, Swisher SG, Chu D. Video-assisted thoracoscopic versus open thoracotomy lobectomy in a cohort of 13,619 patients. Ann Thorac Surg 2010;89:1563 70. 9. Hannan LA, Trivedi PS, David EA, Marshall MB. National outcomes of open and video-assisted thoracoscopic lobectomy using the National Inpatient Sample. Chest 2010;138:760A. 10. Bach PB, Cramer LD, Schrag D, Downey RJ, Gelfand SE, Begg CB. The influence of hospital volume on survival after resection for lung cancer. N Engl J Med 2001;345: 181 8. 11. Birkmeyer JD, Stukel TA, Siewers AE, Goodney PP, Wennberg DE, Lucas FL. Surgeon volume and operative mortality in the United States. N Engl J Med 2003;349:2117 27. 12. Zelen J, Bilfinger TV, Anagnostopoulos CE. Coronary artery bypass grafting. The relationship of surgical volume, hospital location, and outcome. N Y State J Med 1991;91:290 2. 379 13. Casson AG, van Lanschot JJ. Improving outcomes after esophagectomy: the impact of operative volume. J Surg Oncol 2005;92:262 6. 14. Quan H, Sundararajan V, Halfon P, et al. Coding algorithms for defining comorbidities in ICD-9-CM and ICD-10 administrative data. Med Care 2005;43:1130 9. 15. Rueth NM, Andrade RS. Is VATS lobectomy better: perioperatively, biologically and oncologically? Ann Thorac Surg 2010;89:S2107 11. 16. Yim AP, Wan S, Lee TW, Arifi AA. VATS lobectomy reduces cytokine responses compared with conventional surgery. Ann Thorac Surg 2000;70:243 7. 17. Allen MS, Darling GE, Pechet TT, et al. Morbidity and mortality of major pulmonary resections in patients with early-stage lung cancer: initial results of the randomized, prospective ACOSOG Z0030 trial. Ann Thorac Surg 2006;81: 1013 20. 18. Boffa DJ, Allen MS, Grab JD, Gaissert HA, Harpole DH, Wright CD. Data from The Society of Thoracic Surgeons General Thoracic Surgery database: the surgical management of primary lung tumors. J Thorac Cardiovasc Surg 2008;135:247 254. 19. Paul S, Altorki NK, Sheng S, et al. Thoracoscopic lobectomy is associated with lower morbidity than open lobectomy: a propensity-matched analysis from the STS database. J Thorac Cardiovasc Surg 2010;139:366 78. 20. Meguid RA, Brooke BS, Chang DC, Sherwood JT, Brock MV, Yang SC. Are surgical outcomes for lung cancer resections improved at teaching hospitals? Ann Thorac Surg 2008;85: 1015 25. 21. Schipper PH, Diggs BS, Ungerleider RM, Welke KF. The influence of surgeon specialty on outcomes in general thoracic surgery: a national sample 1996 to 2005. Ann Thorac Surg 2009;88:1566 73. INVITED COMMENTARY The article by Park and colleagues [1] supplements an arguably overwhelming body of evidence on the salutary effects of thoracoscopic lobectomy; in addition, this article suggests that the uniformity of its application can affect our interpretation of its outcomes. Many surgeons adopted video-assisted thoracoscopic surgery (VATS) for lobectomy in patients with favorable anatomy who could tolerate technical adverse events, eg, those with thin bodies, good cardiopulmonary function, and complete fissures. Using the long-term perspective, this population also had plenty of potential quality life to lose given a catastrophic technical complication or lack of oncologic equivalence. Since fit patients go home quickly at high-volume centers with efficient care pathways, low-risk VATS adoption may have had little effect on length of stay unless it was extended by a learning curve complication. Alternatively, thoracoscopic lobectomy adopted first in the frail, high-risk population raises the stakes if emergent conversion is needed; yet this is the group for which its differential benefits are maximal. Evidence for this relative risk reduction is found in studies showing that pulmonary function tests that once precluded patients from resection are less predictive, adjuvant chemotherapy starts faster, and independence at discharge is greater for VATS. I propose that the uniformity of thoracoscopic lobectomy application or VATS reliability is a measure of program maturity. In established VATS centers, thoracoscopic resection rates for all isolated lobectomies approach 90%. The adoption approach may have influenced this because high reliability skills accrue faster (by necessity) in the more difficult, high-risk patient for whom conversion is a poor option. Like other endeavors, challenging exercises (or opponents, using a gaming analogy) build skills faster. Given the low acuity adoption philosophy, critics of VATS lobectomy might conclude that its salutary effects, especially in single-institution reports, are the result of its use on patients with better risk factors. Park and associates did a fine job controlling for inappropriate case selection that may have led to misinterpretation of large administrative data sets used to control for this singlecenter bias. We also need to consider another explanation. There may have been temporal bias caused by sampling during the early learning curve adoption years. Learning curve complications may offset the reduced benefits of VATS in a healthy population that tends to go home faster and avoids adverse events. Perhaps more importantly, care pathway changes to speed discharge (such as eliminating the routine use of epidural anesthesia and streamlining chest tube management) are un- 2012 by The Society of Thoracic Surgeons 0003-4975/$36.00 Published by Elsevier Inc doi:10.1016/j.athoracsur.2011.07.034