The decision to proceed with any surgical procedure involves a careful consideration of the anticipated benefits of surgery and an assessment of the risks associated with the operation. An important component of estimating the benefit of surgery is knowledge of the natural history of the condition in question. It is a popular, though inaccurate, conception of the preoperative evaluation that the evaluating physician “clears” the patient for surgery. This implies a binary clinical scenario: Either the patient is at low risk and is “cleared” or the risk is excessive and the patient is “turned down” for surgery. The reality, of course, is more complex and often more gray than black and white. A more accurate view of preoperative evaluation fulfills two goals: first, to accurately define the morbidity and risks of surgery, both short and long term, and second, to identify specific factors or conditions that can be addressed preoperatively to modify the patient's risk of morbidity. The formulation of an approach to accomplish these goals requires knowledge of both the specific characteristics of the patient population and the general effects of thoracic surgery on patients.
Patient Population Undergoing Thoracic Surgery
Many patients undergoing a noncardiac thoracic surgical procedure do so as a consequence of known or suspected lung or esophageal cancer. These diseases share the common risk factor of a significant and prolonged exposure to cigarette smoking and commonly include older individuals. The combination of age and prolonged cigarette smoking yields a population with a significant incidence of comorbid factors beyond the primary diagnosis. A major source of comorbidity in the population of patients with lung cancer is the presence of chronic obstructive pulmonary disease (COPD). The diagnosis of COPD is an independent risk factor for the development of lung cancer, after controlling cigarette smoke exposure.1,2 The combination of these factors, plus the magnitude of the surgical procedures, presents a challenge to the clinicians evaluating such patients. The potential for perioperative morbidity and mortality is substantial, but at the same time, the lack of effective alternative therapy for the patient's malignancy means that the consequence of not being a surgical candidate is almost certain death. This quandary led Gass and Olsen to ask, “What is an acceptable surgical mortality in a disease with 100% mortality?”3
The Charlson Comorbidity Index (CCI),4 which generates a score based on the presence of comorbid conditions, was originally designed as a measure of the risk of 1-year mortality attributable to comorbidity of hospitalized patients. This index has been demonstrated to stratify the risk of postoperative complications in thoracic surgery patients.4,5 In nonsmall cell lung cancer patients, the CCI is a better predictor of survival than individual comorbid conditions and has been recommended for use in the selection of patients for NSCLC surgery.6 A recent study, compared the CCI to another comorbidity index, the Kaplan–Feinstein index ...