Short-term low-dose vs standard-dose Varenicline therapy for smoking cessation: a randomized controlled trial

Aims: Varenicline is used in smoking cessation. The aims of the study were to test for differences in clinical practice between 1mg and 0.5mg (both twice daily during 8 weeks) in abstinence, adherence and side effects. Methods: Open-label randomized parallel-group controlled trial with 1-year follow-up at the Stop-Smoking Clinic of the Virgen Macarena University Hospital in Seville, Spain. Participants were smokers (n=484) of which 59.5% were men with a mean age of 50.67 years-old and a smoking history of 37.5 pack-years. They were randomized to 1mg (n=245) or 0.5mg (n=239) and received behavioural support, which consisted of a baseline visit and 6 follow-ups. The primary outcome was continuous self-reported abstinence over 1 year, with biochemical verification. The secondary outcomes were adherence and side effects. Also measured were baseline demographics, medical history and smoking characteristics. Findings: Abstinence rates at 1 year were 46.5% with 1mg vs 46.4% with 0.5mg (p=1.0). Treatment adherence was similar in both regimens: full adherence 54.1%, partial adherence 13.2% and non-adherence 32.6% (p=0.44). Side effects were reported in 19.3% of cases with 1mg vs 12.1% with 0.5mg (p=0.093). Smokers with partial adherence experienced a higher incidence of side effects comparing to those with full adherence (28.1% vs 12.6%;p=0.004). Conclusions: In this single-center study, there is no difference in smoking cessation effectiveness between 1mg and 0.5mg varenicline both twice daily for 8 weeks, with similar rates of abstinence, adherence and side effects.