Effect of Preoperative Smoking Intervention on Postoperative Complications
June 15, 2002
Effect of Preoperative Smoking Intervention on Postoperative Complications
Abstract & Commentary
Synopsis: An effective smoking intervention program for 6-8 weeks reduces postoperative complications and length of hospitalization.
Source: Moller AM, et al. Lancet. 2002;359:114-117.
Smoking is an important risk factor for postoperative complications. Warner and colleagues demonstrated that smoking cessation for 8 weeks prior to surgery decreases the pulmonary complications after cardiac surgery.1 Many studies have shown that smoking interferes with host defense mechanisms such as clearance of pulmonary secretions, alveolar macrophage function, ciliary motility, wound healing, and collagen production.
In this study, 120 patients who were undergoing elective orthopedic surgery were randomized into a smoking intervention group (60 patients) and control group (60 patients). Smoking intervention consisted of counseling and nicotine replacement, and either cessation or reduction of smoking by half. Both groups were matched for age, sex, body mass index, preoperative physical status, and smoking habits. Investigators who assessed intraoperative and postoperative complications were blinded with respect to treatment group.
Overall, there was a decrease in total complications in the intervention group (10% [10/56] vs 52% [27/52], relative risk reduction [RRR] 65% and number needed to treat [NNT] 3 with 95% CI 2-6; P = 0.0003). Wound related complications were much lower in the intervention group (5% [3/15] vs 16% [31/52], RRR 83% and NNT 4 with 95% CI 2-8; P = 0.001).
Though there was a small reduction in cardiovascular complications (0% vs 10%) and secondary surgery such as replacement and repositioning (4% vs 15%) in the intervention group, this was not statistically significant. Respiratory complications were equal in both groups (2% each).
Interestingly, wound related and other complications failed to decrease in the intervention group in those patients who reduced their smoking by half (27% vs 26% and 46% vs 44%, respectively). Wound related and other complications were significantly lower only among those patients who stopped smoking altogether (0% vs 26% and 4% vs 44%, respectively; P = 0.0004 and P = 0.001) in the intervention group. Moller and colleagues conclude that an effective smoking cessation program applied 6-8 weeks before surgery can significantly reduce postoperative complications.
Comment by David Ost, MD, & Gnanaraj Joseph, MD
While smoking cessation prior to surgery improves perioperative morbidity, the minimal time interval of smoking cessation required for benefit is not known. Warner et al found that patients undergoing cardiac surgery had lower pulmonary complications only if they stopped smoking for 8 weeks.1 Kotani et al suggested that pulmonary defense function (antimicrobial and antiinflammatory functions of macrophages) might be limited for as long as 6 months after stopping smoking.2 Smoking cessation for as little as 24 hours decreases carboxyhemoglobin levels, incidence of perioperative ST-depression, myocardial ischemia, and, most likely, perioperative cardiac mortality.3 However, there is an increased incidence of pulmonary complications if smoking is stopped < 2 weeks prior to surgery.4 Thus, the optimal minimum duration of smoking cessation cannot be determined precisely. In this study, Moller et al used a time interval of 6 weeks of smoking cessation prior to surgery. A smoke-free interval longer than 6 months would be ideal but is not practical. With the available evidence, it is reasonable to conclude that 6 weeks of smoking cessation or longer would be beneficial.
In the intervention group, 36 of 60 (60%) stopped smoking as compared to 4 of 60 (7%) in the control group which emphasizes the fact supported by several other studies that dedicated counseling does increase the smoking cessation rate.
One problem with this study is the small sample size, which limits the ability to precisely estimate the effect size of the intervention implemented. In addition, the intervention group adjusted other lifestyle factors including exercise, diet, and alcohol intake more frequently despite not being counseled to do so. This may have been observed as a confounding variable.
References
1. Warner MA, et al. Mayo Clin Proc. 1989;64:609-616.
2. Skolnick ET, et al. Anesthesiology. 1998;88:1144-1153.
3. Allred EN, et al. N Engl J Med. 1989;321:1426-1432.
4. Bluman LG, et al. Chest. 1998;113:883-889.
5. Frick WG, Seals RR. Tex Dent J. 1994;111:21-23.
Dr. Ost, Assistant Professor of Medicine, NYU School of Medicine, Director of Interventional Pulmonology, Division of Pulmonary and Critical Care Medicine, North Shore University Hospital, Manhasset, NY, is Associate Editor of Internal Medicine Alert. Dr. Joseph is a Fellow in Pulmonary and Critical Care Medicine at North Shore University Hospital.
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