INFLUENCE OF SMOKING STATUS ON DEATH IN VASCULAR SURGICAL PATIENTS FROM THE NATIONAL SURGICAL QUALITY IMPROVEMENT PROGRAM (NSQIP) DATABASE: IS THERE A “SMOKERS PARADOX” ?

Robert S. Crawford, MD, Christopher J. Abularrage, MD, Mark F. Conrad, MD, Richard P. Cambria, MD, Glenn M. LaMuraglia, MD.
Massachussets General Hospital, Boston, MA, USA.

OBJECTIVES: Smokers have been found to have a lower mortality following coronary interventions and this has been labeled the “smoker’s paradox”. This study investigates whether these findings are present in vascular patients.
METHODS: Prospective data from the NSQIP database was analyzed for abdominal aortic aneurysm (Open:AAA or Endovascular:EVAR), infrainguinal bypass (LE) or carotid endarterectomy (CEA) between 1/1/2005 and 12/31/2006. The primary end-point was 30-day mortality. Patient demographic/clinical data associated with mortality was analyzed between smokers and non-smokers using univariate methods to create multivariate models.
RESULTS: There were 8173 patients identified (AAA: 917; EVAR: 765; LE: 2368; CEA: 4123), for which smokers had lower mortality compared to non-smokers (1.9 vs. 2.7%,p=0.04). Sub-analysis revealed smokers had lower mortality (smoker’s “paradox”) in AAA (7.1 vs. 11.8%,p=0.02) and LE (1.7 vs. 3.3%,p=0.02), but not EVAR (0.46 vs. 2.2%,p=0.09) or CEA (0.9 vs. 0.7%,p=0.6) (non-paradox). Demographics/clinical variables in the paradox cohort (AAA-open/LE), identified smokers as younger (63.5±10.3 vs. 71.5±10.5 years, p<0.0001) with more COPD (19 vs. 10%,p<0.0001), but less CHF (3.2 vs. 1.7%,p=0.008), previous coronary surgery (30 vs. 19%,p<0.0001), diabetes (21 vs. 14%,p<0.0001) or dialysis (7.4 vs. 3.5%,p<0.001). There were similar demographic/clinical differences between smokers and non-smokers in the non-paradox cohort (EVAR/CEA), but the overall mortality was lower [44/4888 (0.9%) vs. 154/3285 (4.7%); p<0.0001, 2.73(2.1-3.5)]. Age [p<0.0001, 1.07(1.05-1.1)], emergency surgery [p<0.0001, 8.3(5.6-12.4)] and dialysis [p<0.0001, 2.1(1.16-3.7)] were independent predictors of mortality in the paradox group, but smoking was not.
CONCLUSIONS: Smoking is associated with lower mortality in vascular surgery, primarily AAA repair and LE, but not in patients undergoing EVAR and CEA. This difference may be explained by the magnitude of the surgery and differences in procedural mortality. These data indicate that smoking is not an independent predictor of perioperative death, but as these patients present at an earlier age, is associated with a more favorable renal and cardiovascular risk-profile. Once these predictors of 30-day mortality are accounted for, the smoker’s paradox disappears.

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