Smoking increases the risk for serious complications after major surgery, but
former smokers who stopped 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
Although current smokers were more likely than non-smokers 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%
more likely to die and 53% more likely to have serious heart and lung problems
than former smokers who had quit, according to the results published in JAMA
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% greater risk of heart attack than smokers, compared to a
77% greater risk among current smokers. For pneumonia, former smokers had a 16%
higher risk than never-smokers, but that compared to a 50% higher risk among
current smokers. About 2% of current smokers developed pneumonia post-surgery,
compared to 1 percent of non-smokers.
Quitting can reduce risk
Almost 3% of current smokers ended up on a ventilator for more than 48 hours
post-surgery, compared to 2.8% of former smokers and 1.8% 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 said.
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
"Since patients were not randomised 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 said.
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
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.