The impact of tobacco use on postoperative complications

Abstract

In almost every field of surgery, there have been several reports of an increased frequency of wound healing complications among smokers. There is also evidence of a dramatic drop in the complication rate if a smoking cessation intervention is started 6 8 weeks ahead of orthopaedic surgery. Whether or not this is also true for other surgical procedures has not been studied, and it is not known if even shorter periods of smoking cessation can affect the complication rate. There is little evidence of the long-term efficacy of a perioperative smoking cessation intervention. Very few observations on snus and the rate of postoperative complications have been published. In this thesis, we tried to address these questions and, in addition, we attempted to estimate the impact of obesity on postoperative complications after inguinal hernia surgery and appendectomy. We also estimated the impact of tobacco use and obesity on the perforation rate in appendicitis.

Methods: To study the impact of smoking, snus and obesity on inguinal hernia surgery (Study I) and appendectomy (Study II), we used the Swedish Construction Workers Cohort linked to the Swedish Inpatient Register. The cohort consists of approximately 361,280 individuals. To study the efficacy of a perioperative smoking cessation intervention (Study III) and the possible effects of that intervention on postoperative complications (Study IV), we performed a randomised controlled trial (n=117). The trial compared a smoking cessation intervention introduced four weeks prior to surgery with standard care. The primary outcome was any postoperative complication and the assessment was blinded.

Results: Our results in the cohort studies show that smokers have an increased risk of postoperative complications after inguinal hernia surgery (OR 1.34; 95% CI 1.04 1.72) and after appendectomy due to non-perforated appendicitis (RR 1.51; 95% CI 1.03 2.22). Smoking was also significantly associated with an increased risk of perforated appendicitis (RR 1.29; 95% CI 1.11 1.50). Obesity was also associated with an increased risk of postoperative complications after appendectomy due to non-perforated appendicitis (RR 2.60; 95% CI 1.71 3.95). Use of snus did not affect the frequency of postoperative complications or the rate of perforations. Smoking cessation intervention proved to be effective in our randomised trial. The overall short-term complication rate in the intervention group was 21% compared to 41% in the control group (p=0.03). The relative risk for the primary outcome of any postoperative complication in the intervention group was 0.51 (95% CI 0.27 0.97) and the number needed to treat (NNT) was five (95% CI 3 40). The proportion of abstinent individuals in the intervention group was 58% the week before surgery, the corresponding figure in the control group was 2% (p<0.001). After one year of follow-up one third (33%) of the individuals in the intervention group remained abstinent compared to 15% in the control group (p=0.03).

Conclusion: Smoking increases the risk of postoperative complications even in minor surgery such as inguinal hernia repair. There is also a significant association between smoking and perforated appendicitis. Smoking and obesity are also associated with more postoperative complications after open appendectomy in patients with non-perforated appendicitis. Snus does not seem to affect the complication rate after surgery at all. Smoking cessation programmes can be started successfully four weeks before surgery with long-lasting results. Perioperative smoking cessation is an effective means of reducing postoperative complications even when introduced as late as four weeks prior to surgery.