Abstract
Background and aimsIn smoking treatment trials comparing varenicline with transdermal nicotine replacement therapy (NRT), stratified by nicotine metabolite (3‐hydroxycotinine/cotinine) ratio (NMR), the relative benefit of varenicline is greater among normal rather than slow metabolizers. This study tested if the relative effectiveness of varenicline and NRT is associated with NMR status in a natural treatment setting. A secondary aim was to test if this relationship is moderated by behavioural support.DesignProspective observational multi‐centre study with 4‐week and 52‐week follow‐up.SettingNine English Stop Smoking Services (SSS).ParticipantsData came from 1556 smokers (aged ≥ 16 years) attending SSS between March 2012 and March 2013.InterventionsParticipants received pharmacotherapy together with behavioural support.MeasurementsThe primary outcome was carbon monoxide‐verified continuous abstinence at both follow‐up times. Main explanatory variables were (1) NMR status [slow (NMR < 0.31, n = 451) versus normal (NMR ≥ 0.31, n = 1105) metabolizers]; (2) pharmacotherapy (varenicline versus NRT) and (3) behavioural support (individual versus group‐based treatment). Analyses adjusted for baseline socio‐demographic, SSS, mental/physical health and smoking characteristics.FindingsOf participants, 44.2% [95% confidence interval (CI) = 41.7–46.6%] and 8.0% (95% CI = 6.8–9.5%) were continuously abstinent at 4 and 52 weeks. Varenicline was more effective than NRT at 4 weeks (P < 0.001) but only marginally so at 52 weeks (P = 0.061). There was no or inclusive evidence that NMR status moderated relative efficacy of varenicline and NRT at 4‐ [P = 0.60, Bayes factor (BF) = 0.25] or 52‐week follow‐ups (P = 0.74, BF = 0.73). However, this relationship was moderated by behavioural support (p = 0.012): the relative benefit of varenicline over NRT at 52‐week follow‐up was greater in slow, not normal, metabolizers receiving group rather than individual support (P = 0.012).ConclusionsIn a real‐world setting, the nicotine metabolite ratio status of treatment‐seeking smokers does not appear to contribute substantially to the differential effectiveness of varenicline and nicotine replacement therapy in Stop Smoking Services, when both pharmacotherapy and behavioural support are self‐selected.
Highlights
Despite the existence of effective behavioural and pharmacological smoking cessation interventions, most treatmentseeking smokers will still fail even with additional support [1,2,3,4,5,6,7]
Does nicotine metabolite (3-hydroxycotinine/cotinine) ratio (NMR) status moderate the short- and long-term effectiveness of nicotine compared with non-nicotine pharmacotherapy in Smoking Services (SSS)? The effect of pharmacotherapy on outcomes did not appear to be moderated by NMR status
There was no interaction of NMR status by pharmacotherapy choice on either 4- or 52-week followups when controlling for all other variables
Summary
Despite the existence of effective behavioural and pharmacological smoking cessation interventions, most treatmentseeking smokers will still fail even with additional support [1,2,3,4,5,6,7]. In smoking treatment trials comparing varenicline with transdermal nicotine replacement therapy (NRT), stratified by nicotine metabolite (3-hydroxycotinine/cotinine) ratio (NMR), the relative benefit of varenicline is greater among normal rather than slow metabolizers. There was no or inclusive evidence that NMR status moderated relative efficacy of varenicline and NRT at 4- [P = 0.60, Bayes factor (BF) = 0.25] or 52-week follow-ups (P = 0.74, BF = 0.73) This relationship was moderated by behavioural support (p = 0.012): the relative benefit of varenicline over NRT at 52-week follow-up was greater in slow, not normal, metabolizers receiving group rather than individual support (P = 0.012). Conclusions In a real-world setting, the nicotine metabolite ratio status of treatmentseeking smokers does not appear to contribute substantially to the differential effectiveness of varenicline and nicotine replacement therapy in Stop Smoking Services, when both pharmacotherapy and behavioural support are self-selected
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