Prevalence, trends and outcomes from smoking in elective surgical systems: a secondary analysis of a prospective observational cohort study across 442 hospitals from 29 countries across Europe.

Background: Smoking remains a significant public health issue in Europe, with elective surgery offering a key opportunity for intervention. Knowledge gaps exist around its prevalence and the optimal timing for preoperative cessation to improve outcomes, despite current guidelines recommend smoking cessation up to six weeks prior to surgery. This study aims to address this gap in a large observational prospective cohort study of patients undergoing abdominal surgery across Europe. Methods: We performed a pre-planned secondary analysis of a prospective, international cohort study of patients undergoing elective abdominal surgery between January 24, and May 03, 2022. The primary measure was smoking status and secondary measures were prevalence by age, gender, and number of long-term conditions. Multilevel logistic regression was used to explain the relationship between preoperative smoking status on postoperative overall (primary outcome) and major (secondary outcome) complications. Three-level models were constructed with patients nested within hospitals and countries. Findings: 16,327 patients from 442 hospitals across 29 countries were included. 3179 patients (19.5%, 95% confidence interval (CI): 18.9%-20.1%) were current smokers, ranging from 8.3% to 31.7% across the included countries. Rates of current smokers were higher in younger patients (18-40 vs 41-60 vs 61-80 vs ≥ 81 years: 26.8% [95% CI: 24.8%-28.9%] vs 25.3% [95% CI: 24.2%-26.4%] vs 15.1% [95% CI: 14.3%-16.0%] vs 5.2% [95% CI: 4.0%-6.8%]), male patients (compared to females: 22.1% [95% CI: 22.0%-23.1%] vs 17.2% [95% CI: 16.5%-18.0%]) and healthy adults (compared to one or two long-term conditions: 24.6% [95% CI: 23.2%-25.9%] vs 19.6% [95% CI: 18.6%-20.7%] vs 16.6% [95% CI: 15.8%-17.5%]). 30-day overall complications were higher across current (OR: 1.14; 95% CI: 1.03-1.27), ex-smoker <6 weeks (1.52, 1.10-2.10), ex-smoker 6 weeks-1 year (1.30, 1.01-1.68) and ex-smoker >1 year (1.13, 1.02-1.26) compared to never smokers. No difference was seen for 30-day major complications across these groups. Interpretation: The high prevalence of smoking among elective surgical patients, especially in younger, healthy patients, expose a need to strengthen preoperative cessation strategies. Although uncertainty exist around perioperative outcomes, smoking cessation in the perioperative window is a good opportunity to reach people for long-term health promotion. Embedding high-value strategies into elective surgical systems may serve as a model for broader healthcare reforms, leading to more efficient, preventive care across the entire health system. Funding: The Student Audit and Research in Surgery collaborative is supported with a Strategic Partnership with BJS Society. SKK was funded by the NIHR Doctoral Research Fellowship (NIHR303288).