Introduction UK guidelines for LTx and HTx candidate referral require a minimum of 6 months abstinence from smoking and ALL forms of nicotine replacement before patients can be formally assessed. Our unit adopted this principle and we aimed to investigate smoking habits in a consecutive cohort of such referrals.

Methods Prospectively collected urine cotinine levels were used as a patient engagement tool. LTx referrals from August 2010 to April 2018 and HTx referrals from September 2015 to April 2018 who clearly stated they had met the smoking/nicotine abstinence criterion were asked to submit an on-the-spot urine sample at outpatient consultations and inpatient assessments. Cotinine>50 ng/ml indicated active smoking/nicotine use (liquid chromatography mass spectrometry, lower detection limit 5 ng/ml).

Results 499 LTx and 149 HTx candidates submitted ≥1 sample during this period; total 977 and 220 samples, mean (range): 2 (1–14) and 1 (1–8)/patient; median self-reported nicotine abstinence 1.9 years (IQR 0.8–4.9) and 1.1 (0.2–2.5) respectively. 25.8% (LTx) and 27.5% (HTx) had elevated first sample cotinine [LTx: mean (range) 171 (6–2100) ng/ml, 102/129>50 ng/ml; HTx 111 (6–1100), 30/41>50 ng/ml]. Smokers were predominantly male (LTx-57.4%; HTx-71%, p<0.05) and more likely to have COPD and ischaemic cardiomyopathy as their diagnoses (52% and 59% respectively, p<0.05). After counselling, and a median of 130 and 79 days later, 293 LTx and 49 HTx submitted a second sample: significantly fewer (12%) displayed high cotinine in both cohorts (p<0.05); the number of positives (pos) declined as the number of cotinine tests increased. Abstinence was not always sustained; eg, amongst LTx: 11 had 2 initial pos samples and a negative (neg) third test and 3 had pos-neg-pos results; 5 displayed pos-pos-neg-pos and 2 pos-neg-pos-neg.

Conclusion We found a high prevalence of nicotine ‘mis’-use in patients with advanced pulmonary and cardiac disease selected by referring physicians for consideration of organ transplant having declared long abstinence. Smoking habits changed in both directions with a clear risk of relapse on the waiting list; implications for relapse post-operatively require further study. Urinary cotinine targets can be used to incentivise patients’ behavioural change and set clear expectations within the contract governing relationship with the transplant team.