Smoking Increases Odds of Postoperative Morbidity and Mortality

Jim Kling

November 01, 2010

November 1, 2010 (San Diego, California) — Smokers are at higher risk for mortality and experience more frequent postoperative complications than nonsmokers, according to research presented here at the American Society of Anesthesiologists 2010 Annual Meeting.

Patients often express concern about the effects of smoking on perioperative risks. "If you suggest they quit smoking in this time period, they're more prone to quit. But information [on the actual risks] in the literature is lacking," Alparslan Turan, MD, associate professor of anesthesia at The Cleveland Clinic in Ohio, who presented the research, told Medscape Medical News.

The researchers studied the effect of smoking on 30-day postoperative outcomes in noncardiac surgical patients. They used the American College of Surgeons National Surgical Quality Improvement Program database, and 520,242 of 635,265 patients met the inclusion criteria. Of these, 103,795 (26.5%) were current smokers, defined as having reported smoking cigarettes in the year prior to surgery. The researchers defined smoking quantity in terms of pack-years. They propensity-matched 82,304 of the smokers (79%) to nonsmoker control subjects. They excluded patients who smoked cigars or pipes or who used chewing tobacco. Nonsmokers were defined as people who reported never smoking.

The researchers compared matched smokers and nonsmokers on the major and minor morbidity outcomes and on individual outcomes. Using logistic regression, they also determined the relation between pack-years smoked and any major morbidity.

Smokers had a 38% higher mortality rate than nonsmokers (95% confidence interval [CI], 11 - 72). They also had higher rates of various complications, including pneumonia (209%; 95% CI, 180 - 243), unplanned intubation (87%; 95% CI, 158 - 221), mechanical ventilation (53%; 95% CI, 131 - 179), cardiac arrest (57%; 95% CI, 110 - 225), myocardial infarction (80%; 95% CI, 111 - 292), stroke (73%; 95% CI, 118 - 253), superficial incisional infections (30%; 95% CI, 120 - 142), deep incisional infections (42%; 95% CI, 121 - 168), sepsis (30%; 95% CI, 115 - 146), organ space infections (38%; 95% CI, 120 - 160), and septic shock (55%; 95% CI, 129 - 187).

After adjustment for confounders, the researchers found that for each relative increase in smoking of 10 pack-years, the odds of experiencing any major morbidity increased by 4% (95% CI, 2 - 5). Patients who smoked more than 10 pack-years had disproportionate odds of experiencing any major morbidity.

"This is the biggest study that has ever been done. It will help us a lot in persuading our patients to quit smoking before surgery. [Previous] research has shown that if you quit 2 or 3 weeks before surgery, your chance of complications is dramatically decreased," said Dr. Turan.

Surgery could be an ideal time to convince patients to stop smoking, according to Philip Devereaux, MD, PhD, associate professor of cardiology at McMaster University in Hamilton, Ontario, who attended the presentation. "In the nonoperative world, there is very clear evidence that during periods when people are forced to be nonsmokers, if you can convince them to quit, they're much more likely to comply because they've already started the process. We owe it to these patients not just to correct the surgical problem, but to try to improve their long-term health."

But Dr. Devereaux also sounded a note of caution, noting that the timing of smoking cessation could be an important consideration. "In the nonoperative world, there's this paradox — as soon as [people] stop smoking, their risks instantly rise, and then their long-term risks go down. If that's a true phenomenon, it's possible that in the setting of surgery, withdrawing may not be in your best interest" in the immediate preoperative period, said Dr. Devereaux.

The study did not receive commercial support. Dr. Turan and Dr. Devereaux have disclosed no relevant financial relationships.

American Society of Anesthesiologists (ASA) 2010 Annual Meeting: Abstract 1189. Presented October 19, 2010.

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