The primary aim of this study is to evaluate the effect of preoperative smoking cessation on postoperative complications among patients undergoing surgery. Secondary aims are to evaluate effect on wound complications, short and long term effects including abstinence rate, pain, quality of life and effects on the immune system.

Tobacco smokers suffers from postoperative complications after surgery more extensively than non-smokers. Our primary aim is to study if smoking cessation four weeks prior to elective surgery decreases the number of postoperative complications. Secondary aims is to analyse if smoking cessation four weeks prior to elective surgery decreases wound complications, analyse the effect on abstinence rate, effect on postoperative pain, quality of life and if smoking cessation normalises; the immunological response to surgery.

The study is randomised, prospective, multicenter-based trial. Daily smokers are randomised to 1. Control group (standard care) or 2. smoking cessation. Patients randomised to smoking cessation will undergo professional motivational counselling and will receive free nicotine substitution. The study will include elective cases that are scheduled for surgery. Cessation starts 3-5 weeks prior to surgery. All patients are prospectively followed up for four weeks concerning post-operative complications and for one year concerning other outcomes. Outcome (complications) is registered by a blind observer.

Analyses will be performed by intention to treat. The intervention group is compared with the control group and an adjustment for possible confounders will be done. There will also be an analysis in the subgroups depending on which surgical procedure was performed.Secondary analyses will be by protocol

Inclusion Criteria:

• Active, daily tobacco smokers (> 2 cigarettes daily for at least one year prior to inclusion), 18-79 years old at the time of randomisation.
• Proficiency in the Swedish language.
• Oral and written consent.
• Scheduled for primary inguinal hernia repair or other umbilical hernia repair or laparoscopic cholecystectomy
• Scheduled for hip- or knee replacement

Exclusion Criteria:

• - Active drug abuse or severe mental illness prohibiting compliance with the study protocol.
• Pregnancy.
• Residence outside the county of Stockholm.