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By Kathryn Doyle
NEW YORK (Reuters Health) - Smoking increases the risk for serious complications after major surgery, but former smokers who stop at least a year before going under the knife had risks close to those of never-smokers, according to a new study.
Current smokers in the study had higher risk for heart attack, blood clots, pneumonia, and even death post-surgery compared to people who had never smoked and those who had stopped smoking.
"The adverse long-term effects of smoking are well known, but to have such effects in an acute setting like surgery had not been well elucidated," according to senior author Dr. Faek Jamali of the American University of Beirut Medical Center in Lebanon.
These results add to the spectrum of the damaging effects of smoking, Jamali told Reuters Health by email.
Using the American College of Surgeons database, he and his colleagues examined smoking history, risk factors and complications 30 days post-surgery for 125,000 current smokers, 78,000 former smokers who had quit at least a year earlier and 400,000 people who had never smoked.
The researchers looked for events like heart attack, blood clots, pneumonia and death.
Although current smokers were more likely than nonsmokers to die post-surgery, the former smokers who had quit at least a year before had no increased risk of death compared to the never-smokers.
Current smokers were 17 percent more likely to die and 53 percent more likely to have serious heart and lung problems than former smokers who had quit, according to the results published in JAMA Surgery.
Although increased risk of death was detectable even when someone had smoked the equivalent of a pack a day for 10 years, the authors noted, the longer and heavier the smoking, the greater the risk for complications.
Even when the researchers accounted for the effects of smoking-related diseases, former smokers had a 28 percent greater risk of heart attack than never smokers, compared to a 77 percent greater risk among current smokers.
For pneumonia, former smokers had a 16 percent higher risk than never-smokers, but that compared to a 50 percent higher risk among current smokers. About 2 percent of current smokers developed pneumonia post-surgery, compared to 1 percent of nonsmokers.
Almost 3 percent of current smokers ended up on a ventilator for more than 48 hours post-surgery, compared to 2.8 percent of former smokers and 1.8 percent of never-smokers.
"We knew that smoking increased risk, but it was difficult in past studies to distinguish between risk caused by smoking-related problems like heart and lung disease, and the risk of smoking itself," said Dr. David Warner of the Mayo Clinic in Rochester, Minnesota.
"Knowing that smoking itself is a risk is important because it suggests that quitting can reduce risk," Warner told Reuters Health.
Cigarette smoke has diverse effects on the body and might make surgery riskier in several ways, Warner said.
"For example, carbon monoxide in smoke decreases the ability of the blood to carry oxygen, making complications such as (loss of blood flow to the heart) more likely," he said.
Smokers who have already quit should find these results encouraging, he said.
But the study doesn't conclusively prove that quitting causes risks to go down, according to Judith Prochaska of the Stanford Prevention Research Center in California.
"Since patients were not randomized to continue or quit smoking (or to receive tobacco cessation treatment vs. not), the analyses had to adjust for differences between the three groups because they are likely different in many ways," she told Reuters Health by email.
For instance, former smokers were more likely to be male, white, obese and diabetic than those who had never smoked, she said.
Current smokers were also more likely to have more than two alcoholic drinks per day and to have chronic obstructive pulmonary disease, a breathing impairment caused by smoking.
The results fit in with the overwhelming evidence of the negative effects smoking can have on many body systems, Prochaska said. The results should both encourage smokers to quit and encourage physicians to urge their patients to quit before undergoing major surgery, she said.
"Most smokers want to quit - and surgery is an excellent time for them to do so," Warner said.
The main limitation of the study was that they could not evaluate the effects of living smoke-free for less than a year before surgery, Jamali said, but an impending surgery could be a good time for doctors to talk to their patients about quitting.
Awareness of short-term negative consequences of smoking, like major surgical complications, might be a better motive to quit than the well known long term risks, he said.
SOURCE: http://bit.ly/12Rt6VL JAMA Surgery, online June 19, 2013.