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Relationship between the duration of the preoperative smoke-free period and the incidence of postoperative pulmonary complications after pulmonary surgery.

STUDY OBJECTIVE
To examine the relationship between the duration of the preoperative smoke-free period and the development of postoperative pulmonary complications (PPCs) in patients who underwent pulmonary surgery, and the optimal timing of quitting smoking.


DESIGN
Retrospective cohort study.


SETTING
Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.


PATIENTS
Two hundred eighty-eight consecutive patients who underwent pulmonary surgery between January 1997 and December 1998.


MEASUREMENTS AND RESULTS
We collected information on the preoperative characteristics, intraoperative conditions, and occurrence of PPCs by reviewing the medical records. Study subjects were classified into four groups based on their smoking status. A current smoker was defined as one who smoked within 2 weeks prior to the operation. Recent smokers and ex-smokers were defined as those whose duration of abstinence from smoking was 2 to 4 weeks and > 4 weeks prior to the operation, respectively. A never-smoker was defined as one who had never smoked. The incidence of PPCs among the current smokers and recent smokers was 43.6% and 53.8%, respectively, and each was higher than that in the never-smokers (23.9%; p < 0.05). The moving average of the incidence of PPCs gradually decreased in patients whose smoke-free period was 5 to 8 weeks or longer. After controlling for sex, age, results of pulmonary function tests, and duration of surgery, the odds ratios for PPCs developing in current smokers, recent smokers, and ex-smokers in comparison with never-smokers were 2.09 (95% confidence interval [CI], 0.83 to 5.25), 2.44 (95% CI, 0.67 to 8.89), and 1.03 (95% CI, 0.47 to 2.26), respectively.


CONCLUSIONS
These findings indicate that preoperative smoking abstinence of at least 4 weeks is necessary for patients who undergo pulmonary surgery, to reduce the incidence of PPCs.