Truth vs Test: The Value of Cotinine in Lung Transplant Candidates Assessment

Chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD) account for approximately 80% of all lung transplantations. Cotinine, the main nicotine metabolite, can be measured in serum and is a reliable biomarker of tobacco exposure. According to ISHLT consensus, use of any nicotine-containing product is an absolute contraindication for lung transplantation. This study aimed to assess the frequency and characteristics of active smokers among lung transplant candidates.

We conducted a retrospective study including all patients with COPD or ILD evaluated as lung transplant candidates for the first time at a transplant referral center between November 1, 2020, and December 1, 2023. Serum cotinine was measured using an automated immunoassay (IMMULITE 2000, Siemens HealthCare), with levels >20 ng/mL considered positive.

Of 467 total candidates, 356 patients with COPD or ILD underwent cotinine testing at their initial evaluation (median age 61.86 years). Most were former smokers (90.7%) with a median cumulative tobacco exposure of 40 pack-years. Cotinine was elevated in 52 patients (16.1%). Those with positive cotinine levels were more likely to have COPD, be women, be significantly younger, have higher cumulative tobacco exposure, and report a shorter duration of smoking cessation. Candidates with negative cotinine levels had a higher probability of being listed for transplantation.

A substantial proportion of lung transplant candidates show biochemical evidence of active smoking. Younger patients, women, and those with heavier smoking histories and shorter abstinence periods require closer monitoring. Further studies will assess the influence of personality traits on smoking relapse.