Adverse Post-Operative Events More Common among Current Veteran Smokers Compared with Prior or Non-Smokers

BACKGROUND:
Smoking is the number one cause of preventable death in the U.S. and has been implicated as a risk factor for surgical complications. If smoking-related risk can be defined for patients or procedures, then appropriate interventions can be developed and implemented. This retrospective cohort study assessed the attributable risk and potential benefits of smoking cessation on surgical outcomes for 393,794 Veterans who underwent non-cardiac, elective surgery in a VA hospital between 2002 and 2008. Using data from VA’s Surgical Quality Improvement Program (VASQIP), investigators stratified Veterans as current (n=135,741), prior (n=71,421), and never smokers (186,632). Numerous variables were analyzed, including: pre-operative variables, i.e., demographics, functional status, and comorbidities; operative variables, i.e., type of operation, anesthesia, and blood loss; and post-operative variables, i.e., mortality and/or surgical complications (e.g., pneumonia, wound infection, cardiac event).

FINDINGS:

• Compared with both never and prior smokers – and controlling for patient and procedure risk factors – Veterans who were current smokers had significantly more post-operative pneumonia and surgical-site infection, despite being younger and having fewer comorbidities. Moreover, current smokers had increased odds of dying up to one year after surgery compared with prior smokers or Veterans who had never smoked.
• There was a dose-dependent increase in pulmonary complications based on pack-year exposure (one pack-year equals smoking 20 cigarettes a day for one year), with greater than 20 pack-years leading to a significant increase in smoking-related surgical complications. Prior research suggests that pulmonary complications are the most costly surgical complication, adding an additional $52,000 to the cost of the surgical episode.
• Compared with non-smokers, current smokers were younger and less likely to have diabetes, had more alcohol consumption, and were more likely to have severe COPD. They also were more likely to have general anesthesia and to have undergone thoracic or peripheral vascular procedures.
• Previous literature suggests that pre-operative quit smoking interventions may reduce the risk of post-operative complications. Authors suggest that smoking cessation intervention be considered for Veterans who are current smokers, with greater than 20 pack-years of exposure, who undergo major surgical procedures.

LIMITATIONS:

• Smoking status was collected retrospectively from the medical record, and there is likely some misclassification of current smoker and prior smoker status.
• The study population was primarily male, thus results may not generalize to women undergoing surgical procedures.

AUTHOR/FUNDING INFORMATION:
This study was funded by HSR&D (IAB 06-038). Dr. Hawn is part of HSR&D’s Center for Surgical, Medical Acute Care Research and Transitions, Birmingham, AL. Dr. Houston is part of HSR&D’s Center for Health Quality, Outcomes, and Economic Research in and co-leads VA/HSR&D’s eHealth Quality Enhancement Research Initiative (QUERI), both in Bedford, MA.

Hawn M, Houston T, Campagna E, et al. The Attributable Risk of Smoking on Surgical Complications. Annals of Surgery August 24, 2011;E-pub ahead of print.