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Ann Thorac Surg 2007;84:1098-1106
© 2007 The Society of Thoracic Surgeons

Original Articles: General Thoracic

Obesity Does Not Increase Complications After Anatomic Resection for Non-Small Cell Lung Cancer

Philip W. Smith, MDa, Hongkun Wang, PhDb, Leo M. Gazoni, MDa, K. Robert Shen, MDa, Thomas M. Daniel, MDa, David R. Jones, MDa,*

a Department of Surgery, University of Virginia, Charlottesville, Virginia
b Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia

Accepted for publication April 11, 2007.

* Address correspondence to Dr Jones, Department of Surgery, University of Virginia, PO Box 800679, Charlottesville, VA 22908-0679 (Email: djones{at}virginia.edu).

Presented at the Forty-third Annual Meeting of The Society of Thoracic Surgeons, San Diego, CA, Jan 29–31, 2007.


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
 References
 
Background: The effect of obesity on complications after resection for lung cancer is unknown. We hypothesized that obesity is associated with increased complications after anatomic resections for non-small cell lung cancer.

Methods: A review of our prospective general thoracic database identified 499 consecutive anatomic resections for non-small cell lung cancer from November 2002 to May 2006. Body mass index (BMI) was used to group patients as nonobese (BMI > 18.5 to < 30) and obese (BMI ≥ 30). Patient characteristics and oncologic and operative variables were compared between groups. Multivariable logistic regression models were fit with BMI included at every level. Outcomes examined included in-hospital morbidity, mortality, length of stay, and readmission.

Results: Seventy-five percent (372 of 499) were nonobese, and 25% (127 of 499) were obese. Preoperative variables were similar, except for a greater incidence of diabetes mellitus (p < 0.0001) in the obese group. Overall mortality was 1.4% (7 of 499) and was not different between groups (p = 0.85). Thirty-day readmission rates (p = 0.76) and length of stay (p = 0.30) were similar. Obese patients had a higher incidence of acute renal failure (p = 0.001). A complication occurred in 33% (124 of 372) of nonobese and 31% (39 of 127) of obese patients (p = 0.59). Respiratory complications occurred in 22% (81 of 372) of nonobese and 14% (18 of 127) of obese patients (p = 0.06). Significant predictors of any complication include performance status, diffusing capacity, and tumor stage. Significant predictors of respiratory complications include performance status, diffusing capacity, chronic renal insufficiency, prior thoracic surgery, and chest wall resection.

Conclusions: In contrast to our hypothesis, obesity does not increase the incidence of perioperative complications, mortality, or length of stay after anatomic resection for non-small cell lung cancer.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
 References
 
Complete anatomic resection remains the mainstay of attempted curative therapy for non-small cell lung cancer (NSCLC) in patients with locoregional disease. Non-small cell lung cancer patients frequently have multiple comorbidities that may affect the incidence and impact of respiratory and other complications after resection.

Prior studies evaluating morbidity and mortality after resections for NSCLC have provided little information regarding the impact of patient obesity. Obesity is now epidemic in the United States and other parts of the world. In the United States, the prevalence of obesity has increased from 15% before 1980 to 31% in 1999 to 2002, with more than 65% of US residents currently overweight or obese [1]. In addition to the well known associated health problems, obesity also has enormous financial impact. In 1998 the direct and indirect medical expenses associated with overweight and obesity represented more than 9% of US national health care spending, or 78.5 billion dollars [2]. Compared with nonobese patients, obese patients have more outpatient visits, hospitalizations, prescriptions drugs, and professional claims, with annual health care costs almost twice those of a matched, nonobese cohort [3]. Obesity also is associated with significantly shorter life expectancy, which is synergistic with the shortened life expectancy associated with smoking.

Obesity is associated with increased death rates for all cancers combined, and for malignancies at multiple specific sites including colorectal, endometrial, renal cell, esophageal and postmenopausal breast cancers. The epidemic of overweight and obesity in the United States accounts for up to 14% of deaths from cancer in men and 20% of those in women [4]. Although the data specific to lung cancer have been inconsistent [4–6], obese patients may also be at increased risk of developing lung cancer regardless of smoking status. One reason that data have been conflicting is that it is inherently difficult to analyze risk factors for lung cancer owing to the overwhelming attributable risk of tobacco smoking [7].

Smoking is strongly associated with NSCLC, but is inversely associated with body mass index (BMI). Although more than 40% of US adults are either smokers or obese, only 5% both smoke and are obese [8]. In addition, weight loss and cachexia are common in cancer, although occurring most often in advanced stage disease. Therefore, obesity and NSCLC previously coincided relatively infrequently. It has only been with the recent epidemic of obesity that significant proportions of patients presenting for resection of NSCLC have been overweight or obese. In our recent experience of anatomic resection for NSCLC, almost two thirds of patients are overweight, and one quarter are obese at the time of presentation for resection.

Because obese patients can frequently present significant challenges in operative and perioperative management, surgeons may be reluctant to operate on these patients. Given the ongoing epidemics of both NSCLC and obesity, it is important to further examine the impact of obesity on outcomes after attempted surgical cure of NSCLC. We hypothesized that obesity predicts increased morbidity and mortality after resections for NSCLC compared with nonobese patients.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Comment
 Discussion
 Acknowledgments
 References
 
Patients
Approval with a waiver of individual patient consent was obtained from the Institutional Review Board for Health Sciences Research at the University of Virginia. Data were collected prospectively and entered into our institutional general thoracic database at the point of care. A retrospective review of this database was performed. Patients were included who underwent anatomic resection for attempted cure of NSCLC from November 2002 to May 2006. Procedures were grouped as follows: (1) pneumonectomies and sleeve pneumonectomies; (2) bilobectomies; (3) sleeve lobectomies, Pancoast resections, and lobectomies; and (4) segmentectomies. Nonanatomic wedge resections were excluded as were resections for lesions that represented metastasis or extension from extrapulmonary malignancies, or that proved to be benign on pathologic analysis.

Patient Selection and Management
Operability was determined by standard clinical, radiographic, and staging procedures including bronchoscopy, videomediastinoscopy, and mediastinotomy, as appropriate. Patients deemed to have significant risk factors for coronary artery disease underwent screening by stress echocardiography or stress nuclear imaging with further evaluation and intervention as appropriate.

Patients were admitted the day of surgery unless they required preoperative management of medical comorbidities, which was exceedingly uncommon. All procedures were performed by one of three dedicated general thoracic surgeons. Patients received 24 hours of perioperative parenteral antibiotic coverage with the first dose administered before skin incision. Anatomic resections were achieved using either thoracotomy or video-assisted thoracic surgery (VATS) approaches.

Thromboprophylaxis was maintained with sequential compression devices, early ambulation, and either unfractionated heparin or low molecular weight heparin delivered subcutaneously. Tight management of perioperative blood glucose was achieved with early institution of continuous insulin infusions if rapid control was not achieved with subcutaneous insulins. Postoperative analgesia was achieved in conjunction with our Acute Pain Service using combinations of epidural analgesia (used in all patients where technically achievable and not contraindicated), patient-controlled analgesia, and oral and parenteral adjuncts as needed to facilitate pulmonary and physical therapy. All patients are seen by physical therapy and respiratory therapy postoperatively, with a focus on aggressive pulmonary toilet and early mobilization. Patients are educated regarding incentive spirometry preoperatively and use it frequently postoperatively, including under direct observation. Therapeutic bronchoscopy is instituted early based on clinical findings such as oxygen requirements and correlation with daily chest films. Thoracostomy tubes are removed based on absence of air leak on water seal and absence of pneumothorax on chest x-ray.

Patient Characteristics, Complications, and Outcomes Measured
Patient characteristics recorded include height and weight (see below), sex, age, ethnicity, pack-year smoking history, weight loss in the 3 months before operation, preoperative serum albumin, elements of the medical history including chronic renal insufficiency defined as a serum creatinine value of 2 mg/dL or greater, presence of known coronary artery disease, diabetes mellitus, known cerebrovascular disease or prior stroke, use of chronic systemic steroids, home oxygen or continuous positive airway pressure needs, preoperative pulmonary function tests, history of thoracic surgery, and performance status based on the Eastern Cooperative Oncology Group scale [9]. Pathologic staging was used throughout the analysis and is based on the standard International Staging System for Lung Cancer [10]. Operative variables included extent of resection (grouped as described above), use of thoracoscopic approach, and inclusion of chest wall resection.

Outcomes captured included mortality, length of stay, and in-hospital complications. (Complications captured are those listed in Table 2.) "Air leak" is defined as persistent air leak beyond 7 days postoperatively or those requiring intervention beyond tube thoracostomy. "Bronchoscopy" refers to patients requiring bronchoscopy other than intraoperative bronchoscopy. Acute renal failure was defined as a rise in serum creatinine to 2 mg/dL or greater. All other complications were diagnosed based on standard clinical, laboratory, and imaging characteristics. Mortality includes 30-day mortality, or longer if mortality occurred during the index hospitalization. Patients were said to have "any complication" or "respiratory complication" if they had one or more complication (including death), so that a single patient with multiple respiratory and other complications is counted only once for either group.


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  		Table 2 Outcomes by Body Mass Index (BMI) Group
 
Body Mass Index
Height and weight were measured preoperatively. Body mass index was calculated as patient weight in kilograms divided by the square of patient height in meters (kg/m2). World Health Organization BMI classifications were used as follows; underweight (BMI < 18.5 kg/m2), normal (BMI from ≥ 18.5 kg/m2 to < 25 kg/m2), overweight (BMI ≥ 25 kg/m2 to BMI < 30 kg/m2), and obese (BMI ≥ 30 kg/m2) [11].

Statistics
Statistical analysis was performed using SAS version 9.1 for Windows (SAS Institute, Cary, North Carolina). All p values were calculated using the {chi}2 test for categorical variables and the Student t test for continuous variables. The bivariate relation between independent variables and complications was examined. Those independent variables that were related to outcome at a 0.1 significance level on bivariate analysis were then entered into a backward logistic regression analysis. Body mass index was maintained in the analysis at all steps regardless of significance level. The independent variables chosen in the final model were based on a 0.05 significance level.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Comment
 Discussion
 Acknowledgments
 References
 
There were 518 consecutive anatomic resections for NSCLC performed at our institution during the study period, all of which were captured in the database. Of these, 3.7% (19) were underweight, 35.1% (182) were normal weight, 36.7% (190) were overweight, and 24.5% (127) were obese. Of the obese patients, 13 had BMI of 40 or greater. The BMI distribution of this group is demonstrated in Figure 1. To form our study groups, underweight patients were excluded (n = 19) owing both to their small sample size and their already well established increased risk of postoperative complications. The remaining patients (n = 499) were grouped as nonobese (BMI 18.5 to 29.9, n = 372) and obese (BMI ≥ 30, n = 127).


Figure 1
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  		Fig 1. Histogram depicting body mass index (BMI) distribution for patients undergoing anatomic resection for non-small cell lung cancer during the study period.

 
Epidemiologic, premorbid, operative, and oncologic data for the study population are presented in Table 1. In general, the groups were well matched. As expected, the obese population had a higher incidence of diabetes than nonobese patients. Obese patients also had slightly better pulmonary diffusion capacity for carbon monoxide (DLCO), and more frequently underwent thoracoscopic resection. There were trends toward more obese patients being female and having squamous histology malignancies. Ten percent of patients (51 of 499) received some form of induction therapy. Thirty-three patients had induction chemotherapy plus radiation, 14 patients received chemotherapy without radiation, and 4 patients received radiation therapy alone. Those receiving induction therapy were equally distributed between the obese and nonobese groups (p = 0.87) and had equivalent performance status at the time of resection as those who had not received neoadjuvant therapy (p = 0.73). There was no correlation between preoperative serum albumin levels and BMI (R2 < 0.01 on linear regression).


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  		Table 1 Patient, Tumor, and Operative Characteristics
 
Outcome distributions for obese and nonobese patients are given as Table 2. Notably, we found no difference in unadjusted mortality, length of stay, or overall incidence of complications between obese and nonobese patients. Obese patients demonstrated a strong trend toward fewer respiratory complications than nonobese patients. The primary causes of death for the 5 deaths in the nonobese group were pneumonia (3), acute respiratory distress syndrome (1), and methicillin-resistant staphylococcal septicemia (1). The two deaths in the obese group were due to concomitant stroke and myocardial infarction (1) and pneumonia (1). Therefore, pulmonary complications were the cause of death in 5 of 7 deaths. Obese patients had a significantly higher, although still low, incidence of renal failure than nonobese patients. Of the 5 obese patients who had acute renal failure, 3 had prior chronic renal insufficiency and 3 had prior diabetes, with 2 patients having both preexisting chronic renal insufficiency and diabetes. Only 1 patient in the obese group required hemodialysis, which was discontinued before discharge.

We next examined the relationship of individual variables to incidence of complications. All variables given in Table 1 were evaluated on bivariate analysis, however those with p > 0.1 on bivariate analysis are not tabulated. The summary of these results are presented as Table 3.


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  		Table 3 Variables With Significance of p ≤ 0.1 on Bivariate Analysis
 
The results of the backward regression analyses performed using variables shown in Table 3 in addition to BMI are summarized in Table 4. Body mass index group continued not to be significantly associated with respiratory or other complications when adjusted for covariates. Performance status other than zero was the strongest predictor of complications for both models. The odds ratios and associated confidence intervals for individual tumor stages are not listed, but followed a trend of increasing risk of complication with increasing pathologic tumor stage.


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  		Table 4 Results of Multivariate Analysis
 

   Comment
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
Discussion
 Acknowledgments
 References
 
In contrast to our working hypothesis, obesity was not associated with increased incidence of morbidity or mortality in patients after anatomic resections for NSCLC. Interestingly, we observed a strong trend toward a protective effect of obesity on respiratory complications compared with nonobese, nonunderweight patients. We observed similar findings on both forward and backward logistic regression although the results are only shown for the backward regression.

Morbidity and mortality after resections for NSCLC are lower now than in the past [12]. Although reported perioperative mortality rates have ranged widely in individual series, a large registry report of nearly 8,000 patients demonstrated 3.1% 30-day mortality [12]. A recent multiinstitutional prospective trial of more than 1,100 patients reported 1.4% 30-day mortality [13]. Our 1.4% mortality rate is, therefore, well within accepted standards.

The factors that we found to be significant predictors of morbidity are confirmatory of other studies. Most studies report at least one aspect of TNM staging to be related to prognosis [14]. Performance status is a well-known prognostic indicator in many diseases, including NSCLC [15]. The DLCO can be a powerful predictor of major and minor complications, either alone or as a product with the forced expiratory volume in one second (FEV1) [16–18]. Chest wall resections are reported to be associated with as high as 50% overall, and 30% respiratory, complication rates [19–21].

Malnutrition is a documented risk factor for respiratory complications, more rapid recurrence, and worse overall survival after surgical therapy for NSCLC [14, 17, 22–24]. On the other extreme of BMI, no published study has focused on the impact of obesity on outcomes after NSCLC resection, although several studies have included obesity as one variable [17, 18, 20, 21, 25]. Other studies had a significantly lower percentage of obese patients than our cohort, as low as 0.7% in a series spanning 1983 to 1986 [21]. Those studies that included obesity made little comment on its prognostic implication after NSCLC resection. In a study of pneumonectomy patients in which 10% were obese, 30-day mortality and cardiac morbidity were nonsignificantly higher in obese patients, while respiratory morbidity was slightly lower in obese patients (p = not significant) [20].

Whereas underweight patients generally are significantly malnourished, BMI does not necessarily correlate with other measures of nutrition. Obese patients may be significantly protein malnourished compared with those with lower BMI. In our data, we found no correlation between preoperative albumin and BMI. We do not have other anthropometric measures such as skinfold thickness for our patients. We also do not have other laboratory determinants of nutrition such as serum transferrin. These other measures may be particularly relevant, as many of our patients have such elevated BMI at baseline that even significant malignancy-associated weight loss may leave them overweight or obese by BMI criteria.

We found a strong trend toward fewer respiratory complications in obese compared with nonobese patients (p = 0.06 on bivariate and p = 0.15 multivariate analysis). This trend is particularly striking since we likely would have seen greater significance if underweight patients were included. The data reveal several potential reasons for this trend. Although there is no difference between groups for baseline FEV1, obese patients have better baseline DLCO, the prognostic value of which is discussed above. Although we included pack-years of smoking in our analysis, we did not include current smoking status. Compared with former or never smokers, there was a strong trend toward fewer current smokers in the obese group, 27% compared with 36% of nonobese patients (p = 0.06). This may be of prognostic importance [26], and may also explain the observed difference in DLCO. Female sex has been associated with lower complication rates [27, 28], and there is a trend toward a greater proportion of female patients in the obese group. Sex, histology, and DLCO were all entered into the multivariate models, although only DLCO remained in the final model for respiratory complications.

Prior studies on the effect of obesity on outcomes after procedures other than pulmonary resections have produced varied results. Obese patients have significantly decreased long-term survival after lung transplantation compared with nonobese patients [29]. Several studies have shown a protective effect of obesity after cardiac interventions including improved 1-year survival after left ventricular assist device placement [30] and decreased major in-hospital complications after percutaneous angioplasty [31]. The same study found no effect of obesity on complications after coronary bypass grafting. Studies in general surgery procedures have frequently demonstrated that obesity does not increase significant morbidity or mortality after procedures including gastric cancer resections [32], nephrectomy [33], kidney transplantation [34], and hysterectomy [35]. Multiple studies examining the effect of obesity on outcomes after colectomy have shown increased operative time, ileus, wound infection, anastomotic leaks rate, and general morbidity, although other studies have shown no difference (reviewed in Lascano and coworkers [36]). A prospective study of more than 6,000 patients undergoing elective general surgery, excluding thoracic surgery, found that there was no difference in complication rates for obese patients, other than an increased incidence of wound infection [37]. These findings, along with the results of other studies not reviewed here, suggest that the impact of obesity on postoperative outcomes varies with the underlying pathology, with the procedure, and is likely a complex relationship.

Our study is subject to the limits of any retrospective, single-institution review. Another potential limitation is selection bias. We know that 63% of patients who present to our general thoracic surgery clinic for evaluation of primary lung cancer undergo operation for staging or treatment [38]. Those data are not stratified by BMI, so we do not know what percentage of obese patients is eventually offered resection. The perceived risk of morbidity and mortality may have caused us to be more stringent in our selection of obese patients for resection compared with patients of normal BMI. We believe that this is unlikely since patients were subject to the same evaluation regardless of BMI. Further, a large percentage of patients who proceeded to resection was overweight or obese.

The minimally invasive VATS approach to pulmonary resection is documented to decrease postoperative pain, to better preserve pulmonary function, and to allow earlier return to activity (reviewed in Yim [39]). We performed VATS procedures approximately twice as often in our obese patients (Table 1). It is possible that the trend toward improved respiratory outcomes in our obese patients is in part attributable to this confounder. Body mass index has not previously been a factor in our choice of open versus VATS approaches. While our available data do not clearly demonstrate that the VATS technique is superior to thoracotomy for obese patients, they are provocative.

Owing to the same perceived risk, it also is possible that we managed obese patients differently postoperatively. We pursue a policy of aggressive pain control, mobilization, pulmonary toilet, and physical therapy in all patients, which is outlined in the methods section. We may have been more aggressive in these areas in our obese patients, thus contributing to their low rate of respiratory complications.

This study is unable to draw conclusions regarding resource utilization or costs associated with evaluating and managing obese patients with NSCLC. Even in the absence of complications, obese patients require heavy resource utilization for preoperative evaluation and perioperative care. Increased use of staff and specialized equipment, such as patient lifts and specially designed operating room and floor beds, leads to increased cost [40]. Obese patients require longer times in the operating room owing to challenges in airway management, positioning, and the technical performance of the procedure [40]. Obese patients also have greater medication requirements [40]. As one example, it is reasonable to assume that our obese patients, who had a higher incidence of diabetes, more frequently required insulin infusions. Thus, while not fully explored by this study, it is likely that lung resection in the obese patient is an expensive and labor-intensive endeavor.

A remarkable percentage of our patients who underwent resection for attempted cure of NSCLC were either overweight or obese. With childhood and teenage obesity on the rise, the epidemic of obesity will continue to expand and thoracic surgeons will see increasing percentages of obese patients with NSCLC. Further studies will need to focus on resource utilization for thoracic surgery in obese patients. The results of our study are provocative in challenging assumptions about outcomes after thoracic surgery in obese patients. Our results suggest that it is unwarranted, based on current knowledge, to avoid surgical intervention in obese patients who are otherwise appropriate candidates for resection of NSCLC.


   Discussion
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Discussion
Acknowledgments
 References
 
DR G. ALEXANDER PATTERSON (St. Louis, MO): I noticed from one of your early slides that the state I live in is a nice bright red color, indicating lots of obesity. And I think what we should do is start sending all those obese patients to Charlottesville. I don’t believe your study. I mean, that can’t be true. Do you know what I mean?

DR SMITH: That was our initial reaction as well.

DR PATTERSON: Okay. Good. Makes me feel better.

DR CAROLYN E. REED (Charleston, SC): Very nice presentation. We, actually, in Charleston, had the same hypothesis for our obese esophagectomy patients, yet our findings absolutely mirrored yours. However, I believe we do make subtle changes in our approach, in our care, selection, et cetera, for these patients. Could you maybe elaborate a little bit on what you think you might have subtly changed for your obese patients.

And second, I do think the cost is greater for taking care of these patients. It would be interesting if you have any more data on that.

DR SMITH: Thank you very much, Dr Reed. In terms of management changes, it’s a difficult thing to evaluate objectively. In speaking to all of the attending surgeons for these patients, we probably are more aggressive in aspects of management of these patients. For instance, if an obese patient is demonstrating any evidence of respiratory decline, we may be more aggressive in evaluating and maximizing their pulmonary toilet.

We did perform thoracoscopic resections more frequently in the obese patients. While this is not a stated part of our operative planning, doing so in obese patients may have allowed us to decrease pain, decrease the incidence of wound infections, and assist with pulmonary toilet in that way. With regard to the cost, we don’t have any objective data. It is my belief as well, and it’s been shown in general surgery and in other procedures, that there are increased costs associated with managing obese patients. I absolutely agree that obesity and its associated comorbidities are a very serious health problem. Our findings should not be interpreted to imply otherwise.

DR MALCOLM M. DECAMP (Boston, MA): I appreciate that very much. I wondered if you looked at BMI as a continuous variable in your model? You’re right, the definitions are very clear about what we consider as obesity. When we looked at lung transplant morbidity using BMI as a continuous variable, we found increased risk both as a continuous variable going up, and then a categorical variable for the very low weight person. So I wonder if that might add some strength to your argument.

DR SMITH: We have not performed the analysis looking at BMI as a continuous variable. The reason we chose to use the cutoffs is because those are the accepted definitions in clinical practice. However, it would be interesting to do that analysis. I don’t have the specific data, but anecdotally there was a high incidence in complications in the underweight patients who were not included in this study. We did look briefly at our small cohort of patients with a BMI over 40. There were only 13 patients; but in that small group, there were no mortalities and there was no difference in complication incidence in that group compared with other groups.

DR RICARDO S. SANTOS (Pittsburgh, PA): I am glad to see your results. By coincidence, we presented similar results in lung transplantation during the poster section of this meeting. We had the same number of patients following lung transplantation, 517 patients. And, like your results, and the results after esophagectomy presented by our colleague, we didn’t see any statistically significant difference.

I agree with Dr DeCamp about the continuous analysis. however, I also believe that the statistical methodology should be simple and not be changed based on unexpected results. Therefore, I think the best way to see this group of patients is to look in the simple way, as you did. We did exactly the same thing that our colleagues did, a simple comparison between groups.

The number of obese individuals has increased in Pittsburgh and worldwide. Over the last years we observed a higher number of patients with abnormal BMI (underweight or obese). These results should probably reflect a better quality of care. Other institutions should reevaluate the results on surgery for the obese population, by utilizing large samplings to avoid statistical biases. We have a lot of obese patients, again volume wise. I agree it is difficult to explain the same good results. It was also impressive to us what we have found.

But just to emphasize, and I would like your opinion, we keep the same old recommendation for obese patients to lose weight, and for the underweight patients to try to gain weight before the surgery. However, we try don’t delay the lung transplantation, or don’t delay lung intervention if patients have no other associated severe comorbidities. Thank you very much.

DR SMITH: Thank you.

DR JESS SCHWARTZ (Albuquerque, NM): I was wondering if you had looked at any factors in nutritional status in these patients such as albumin, prealbumin? Maybe obesity is a surrogate for lack of malnutrition in your patient population?

DR SMITH: The only other objective measure of nutritional status that we had was albumin. I did a linear regression to see if there was any association between BMI and albumin, and there was zero association; R2 of less than 0.01. We don’t have transferrin or other measures of body fat other than BMI. Therefore, we are unable to further comment on the true relation between nutrition and BMI.

DR JEMI OLAK (Bakersfield, CA): Just to continue Dr Patterson’s question, your conclusions don’t have face validity. It doesn’t make sense that obese patients shouldn’t have more respiratory complications. So my question is, are you planning to prospectively study this same issue?

DR SMITH: We are not actively pursuing that, although it would certainly be an interesting study. I agree that the results are surprising. However, these results actually are consistent with the available literature. The general surgery literature contains multiple retrospective studies of various procedures, and one large prospective study of all general surgical patients. These have consistently demonstrated findings similar to ours. They usually find increased operating time and estimated blood loss, but otherwise demonstrate no difference in length of stay or in-hospital morbidity and mortality. As she mentioned, Dr Reed and colleagues have shown similar findings for esophagectomy. There are at least two other pertinent studies presented at this meeting. One showing no survival difference for obese lung transplant patients, as Dr Santos has already mentioned, and another study in esophagectomy patients. So while this is a surprising finding, it has now been shown in multiple procedures.

DR JOHN R. HANDY (Portland, OR): An alternative title to your study might be "Anatomic Minimally Invasive Resection Mitigates the Risk of Obesity." Did you do any sort of analysis to refute that title?

DR SMITH: No, although it is something that we have considered. The minimally invasive procedure may be a better procedure in these patients. I don’t think that we can firmly support that conclusion from the data that we currently have, but it would be another interesting thing to look at in these patients.

DR MICHAEL S. MULLIGAN (Seattle, WA): I know nobody wants to believe it, but please refer to abstract No. 77, a BMI greater than 35—being presented in the next room—does not increase the morbidity associated with esophagectomy either. So it may be unfortunately true that we have to continue to operate on these patients.

DR SMITH: Findings very similar to those of Dr Reed.


   Acknowledgments
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
References
 
This work is supported in part by National Institutes of Health Cardiovascular Surgery Research Training Grant T32 HL007849 (to Dr Smith).


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Comment
 Discussion
 Acknowledgments
 References
 

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