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Eur J Cardiothorac Surg 2006;29:20-25
© 2006 Elsevier Science NL
Hospital de Gran Canaria Dr. Negrín, Barranco de la Ballena s/n, 35020 Las Palmas de Gran Canaria, Canary Islands, Spain
Received 17 August 2005; received in revised form 7 October 2005; accepted 10 October 2005.
* Corresponding author. Tel.: +34 928 450647; fax: +34 928 450044. (Email: jfregil{at}gobiernodecanarias.org).
| Abstract |
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Key Words: Lung cancer Surgical treatment Morbidity Mortality
| 1. Introduction |
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Several more extensive studies have also been conducted comparing the various types of surgery in large population groups [1012]. These studies analyze the relationship between surgical volume and operative mortality in several types of cardiovascular surgery and in cancer resections. In general terms, the conclusions reached are that it is advisable to perform complex surgical procedures in large-volume hospitals. A recent article sought to carry out a more detailed analysis by studying surgeon volume on an individual basis [13].
Bronchogenic carcinoma (BC) is the main cause of death of neoplastic origin in our setting in the male population and an important one in women. Surgical resection continues to be the best therapeutic option to treat this disease. Nevertheless, only a limited number of patients can benefit from this option, be it because the disease is in a very advanced stage at the time of diagnosis or because there are other causes of functional or oncological inoperability [14]. In lung resections for BC, the number of procedures per year with regard to a particular hospital varies greatly. This consideration has also been the subject of previous studies, although very few have made specific reference to BC [15,16]. No study of this nature has been conducted in our country to date.
Based on the experience gained by the Bronchogenic Carcinoma Cooperative Group of the Spanish Society of Pneumology and Thoracic Surgery (GCCB-S), the aim of this paper is to analyze the impact that hospital volume has on the operative morbidity and mortality risk and on the prognosis of patients with thoracotomy due to BC.
| 2. Materials and methods |
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We included prospectively all patients treated surgically from October 1993 to September 1997 in hospitals participating in the GCCB-S. The annual cumulative number of cases was close to 50% of the surgical cases occurring in Spain. The participating GCCB-S hospitals had a wide variety of activities, including a representative range of number of beds, teaching or research activities (university and non-university hospitals), public and private ownership, and number of interventions per year (from 8 to 100 interventions were performed in participating hospitals for this disease). All cases were collected and followed up prospectively by the thoracic surgeon responsible for each of the centers participating in the study. The sample was complete, as verified by the inclusion in the registry of all patients undergoing surgery, including incomplete resections and exploratory thoracotomy.
Operative mortality was understood to include all deaths directly related with the surgical act, regardless of time of occurrence. We have used this concept in order to consider broad clinical criteria, trying to include late mortality though related with surgery [17]. However, 30-day mortality rate is also considered. The final number of cases included in the study was 2994.
2.2 Methods and analysis
The 1997 TNM staging classification currently in effect was used in this study. The degree of certainty of the TNM stages classification depends on the diagnostic methods used; according to some international organizations post-mortem study yields the maximum certainty factors, and the clinical findings yield the minimum certainty. By ensuring consensus among the members of the GCCB-S coordinating group (two thoracic surgeons and one pneumologist), we established the methods for affirming maximum classificatory certainty for each component (maximum possible clinical certainty adjusted for each problem). Lymph node categories (N) were evaluated using different diagnostic criteria of classificatory certainty. In order to confirm a clinical N0 classification, the absence of lymph node enlargement or lymph node enlargement of less than 1 cm in diameter had to be confirmed by CT in lymph node areas 4, 7 and 10. Moreover, no lymph node enlargement should be present in the aorto-pulmonary window or in the anterior mediastinal area (areas 5 and 6), if the BC is left-sided (upper lobule or main left bronchi). If these criteria were not met, negative mediastinoscopymediastinotomy or negative fine-needle aspiration biopsy (transbronchial, transthoracic, or transesophageal) of these areas was required. The clinical N1 classification was confirmed by cytohistological evidence (transbronchial fine-needle biopsy and hilioscopy). To confirm a clinical N2 classification, cytohistological evidence was required (mediastinoscopy, mediastinotomy, and fine-needle aspiration biopsy using any approach).
Surgical pathological N0 was classified by radical mediastinal lymph node dissection or sampling of at least four lymph node areas (2 [only in right BC], 4, 7, and 10 on the same side as the tumor), especially in postoperative T3.
Internal and external audits were made to survey the ratio between the number of patients undergoing surgery and the cases included in the registry (standard over 95%), the presence and validity of the data recorded for each case (standard over 70%), including the consistency of tumoral staging. The criterion for the validity of the survival data was established as the existence of a known follow-up for 85%, or more, of the cases registered in each hospital. In the hospitals that did not meet these conditions, the cases corresponding to the period of problems were excluded. Finally, correct data transmission by a single central office from the paper record to the computer database was verified.
These procedures were designed to control the selection bias of surgical cases, registered cases out of the total number of surgical cases, sample size, type of hospital, prognostic migration due to prolonged case recruitment, classification with low or deficient degrees of certainty, contamination of data from incomplete series or incorrect data, and loss of long-term follow-up.
To establish the corresponding comparisons, we divided the hospitals into three different types, according to the number of cases operated on per year (Tables 1 and 2 ). To put the groups together we chose as an intermediate group which best reflects the majority of Thoracic Surgery groups in Spain around 50 cases/year. We also decided to form two further groups, less than 43 and more than 55 cases as the most extreme groups in terms of volume of procedures performed per year.
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This study analyzed the following parameters for each group of hospital: rate of complete surgery, postoperative complications and postoperative mortality. Morbidity and mortality in pneumonectomies and in patients 75 years and above was also specifically evaluated. Overall survival at 5 years and in initial stages (I and II) for each group of hospitals was also evaluated.
The comparison of patient characteristics among the different groups was carried out using one-way analysis of variance (ANOVA). The survival analysis was performed employing the KaplanMeier test. Comparisons of survival curves were examined using the log-rank test. Mortality was analyzed by means of a binomial logistic regression model and adjustments were considered for the following risk factors: age, sex, previous tumor, peripheral vascular disease, weight loss, systemic arterial hypertension, diabetes, level of dyspnoea, symptoms, to be bedridden, COPD, ischemic cardiopathy and type of surgery (exploratory thoracotomy and incomplete surgery).
| 3. Results |
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Neither the overall morbidity nor the operative mortality (overall or <30 days) differs among the three groups (Table 3). Neither was there significant differences between the extreme groups (A and B) (Table 4 ). After adjusting mortality for the different risk factors, we did not find significant differences among the three groups (Table 5 ). The variables that increased the postoperatory risk were the performance of an exploratory thoracotomy (OR 7.27), to be bedridden (OR 4.38), the accomplishment of an incomplete surgery (OR 3.13), the presence of a previous tumor (OR 1.59), the existence of peripheral vascular disease (OR 1.59) and to have symptoms (OR 1.34). There were no differences in morbidity or mortality with regard to pneumonectomies or in operations performed on patients above the age of 75 (Table 6 ). Nevertheless, the differences were close to having statistical significance (p = 0.1) for mortality in pneumonectomies between groups I and II.
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| 4. Discussion |
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Our paper presents very specific characteristics. The first of these characteristics is that our study has been carried out within the framework of a national multicenter setting, a particularity unseen in other studies. The study required the prospective compilation of data case-by-case. No loss of data occurred thanks to a continued revision by the Coordinating group in charge of the study. Previously established common criteria, agreeable to all the participating hospitals, were selected, giving the sample very high homogeneity, as verified by all the audits performed throughout the course of the study.
Operative mortality showed identical percentages for groups II and III and somewhat higher percentages but with no statistical significance for group I. As a whole (around 8%), operative mortality does not present values that would make it higher than the international standards or higher than those reported in similar works [1012]. Postoperative morbidity was not significantly different among the three groups either, reaching around 35%. This is not a figure that differs greatly from the usual standards in this type of surgery [19]. The rate of curative surgery was better in low-volume hospitals, followed by larger-volume hospitals and, lastly, by hospitals with an intermediate volume, a rate of 76%. These data are hard to explain, and in any case, appear to indicate that departments with less volume achieve even better figures in relation to this parameter.
One of the most feared interventions because of the morbidity and mortality it entails is pneumonectomy. A number of authors claim that the indication of this type of operation must always be considered with extreme caution in the elderly [20], being an operation with one of the highest morbidity rates [10]. In our paper, we have compared morbimortality in this type of intervention in the three groups but have failed to find any statistical significance. We also performed the same comparison in patients over the age of 75, obtaining identical results. This defers from previous papers in which the biggest and most significant differences are obtained in pneumonectomies [10,12] and in elderly patients [12].
As far as long-term survival is concerned, several parameters seem to play a role, making it difficult to ascribe the experience of the department as just "a single factor". However, equalness of outcome results has been noted among the three studied groups and overall figures are very similar to those reported in papers dealing with survival in BC. A survival rate of around 40% was found in the three groups similar to one reported in the study by Bach et al. [15] for the most experienced group. This appears to confirm the good results that, in any case, groups I and II have despite a lower volume of interventions.
Our findings show a high level of equality among the different Spanish hospitals. These data contradict previous studies in the surgery of BC [1012,15,16] and in other types of surgery [1,3,512]. The fact that the majority of thoracic surgery is performed in specialized referral centers, by the hand of thoracic surgeons that have trained in a common standardized national program can prompt these very similar results among the different participating departments. Previous studies show the improvement that for the healthcare system represents operating BC by properly trained specialists in thoracic surgery [21,22], as supported by the findings yielding by this study. Very recent studies mention the little importance that hospital or department volume appears to have on the better outcome of a given technique, emphasizing the need to identify other quality parameters [2325].
We, thus, conclude that in our medium, the procedural volume of lung resection interventions for BC performed in Departments of Thoracic Surgery does not appear to influence, in general, a better or worse outcome.
| Appendix A |
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Local representatives: J. Astudillo, P. López de Castro (Hospital Hermanos Trías y Pujol, Badalona); E. Canalís, J. Belda (Hospital Clínico, Barcelona); A. Cantó, A. Arnau (Hospital Clínico, Valencia); J. Casanova, M. Mariñán (Hospital de Cruces, Baracaldo); J. Cerezal, F. Heras (Hospital Universitario, Valladolid); A. Fernández de Rota, R. Arrabal (Hospital Carlos Haya, Málaga); F. González Aragoneses, N. Moreno (Hospital Gregorio Marañón, Madrid); N. Llobregat, J. Antonio Garrido (Hospital Universitario del Aire, Madrid); N. Mañes, Helena Hernández (Fundación Jiménez Díaz, Madrid); J. Freixinet, M. Hussein (Hospital Universitario Dr. Negrín, Las Palmas de Gran Canaria); M. Serra (Hospital Mutua de Tarrasa, Barcelona); J.L. Martín de Nicolás, C. Marrón (Hospital Universitario 12 de Octubre, Madrid); N. Novoa, G. Varela (Hospital Universitario, Salamanca); J. Rodríguez, F.A. de Linera (Complejo Hospitalario, Oviedo); A. Torres, A. Gómez (Hospital Universitario San Carlos, Madrid); M. De la Torre, J.J. Rivas (Hospital Juan Canalejo, La Coruña); A. Sánchez-Palencia, F.J. Ruiz-Zafra (Hospital Virgen de las Nieves, Granada); A. Varela, P. Gámez (Clínica Puerta de Hierro, Madrid); Y. Wah Pun (Hospital Universitario de la Princesa, Madrid).
Data analysis: P. Ferrando, A. Gómez de la Cámara (Unidad de Epidemiología Clínica, Hospital Universitario 12 de Octubre, Madrid).
| Acknowledgments |
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| Footnotes |
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| References |
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