Smoking is negatively implicated in healing and may increase the risk of surgical complications in orthopaedic patients. Carbon monoxide (CO) breath testing provides a rapid way of measuring recent smoking activity, but so far, to our knowledge, this has not been studied in elective orthopaedic patients. We studied whether CO-testing can be performed preoperatively in elective orthopaedic patients and whether testing accurately correlates with self-reported smoking status?

CO breath testing was performed on and a brief smoking history was obtained from 154 elective orthopaedic patients on the day of surgery. All patients admitted over 6 weeks for elective orthopaedic intervention were enrolled.

16.2% patients admitted to smoking. The mean CO levels were 15.2 ppm for self-reported smokers and 3.1 ppm for self-reporting non-smokers. One self-reporting non-smoker admitted to smoking after testing. 5 non-smoking patients had a CO breath of >=7, 1 had a CO level of >= 10 ppm. Using a cutoff of 7 ppm gave a sensitivity of 65.4% and a specificity of 96.1%, whilst a cutoff of 10 ppm gave a sensitivity of 57.6% and specificity of 99.2%.

Whilst most patients are honest about smoking, CO testing can identify non-disclosing smokers undergoing elective orthopaedic procedures. Due to the high specificity, speed and cost-effectiveness, CO breath testing could be performed routinely to identify patients at risk from smoking-related complications in pre-assessment clinics. Smoking cessation services may reduce the risk of harm. CO testing on admission may demonstrate the efficacy of smoking cessation services.