Author Affiliations: United Kingdom Centre for Tobacco Control Studies, Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary, University of London (Drs Hajek and McRobbie and Ms Myers), and Cancer Research United Kingdom Health Behaviour Research Centre, University College (Mr Stapleton), and Barts and The London National Health Service Trust (Dr Dhanji), London, England.
Dhelaria and Rothberg point out the differences between success rates in our control group (standard varenicline regimen)1 compared with those in varenicline pivotal trials and trials in people with cardiovascular and chronic obstructive pulmonary disease. We have addressed this issue in our article.1 Comparisons across studies pose numerous problems especially if “success rate” means different things in different studies. The trials Dhelaria and Rothberg cite based their outcomes on no smoking between weeks 8 and 12, ie, over 4 weeks, while our abstinence rates are based on no smoking between the target quit date (TQD) and week 12, ie, over 12 weeks. The cited trials also had a large number of exclusion criteria, while ours had very few. In a comparable study from our clinic assessing continuous abstinence from TQD, the 4-week and 12-week abstinence rates in patients using different nicotine replacement products were 30.7% to 38.1% and 19.7% to 24.4% at 4 and 12 weeks, respectively.2 The abstinence rates in our control group of 33.3% and 20.8% at 4 and 12 weeks, respectively, are perhaps marginally low but not out of range. The results of the UK Stop Smoking Service, of which our clinic is a part, are another possible benchmark to compare our results with. The service does not report 12-week abstinence rates, but it has a carbon monoxide validated rate of abstinence between weeks 2 and 4 (ie, over 2 weeks) of 33.8%.3 The 33.3% rate of abstinence in our control group between TQD and week 4 (ie, over 4 weeks) is again within the expected range.
Hajek P, McRobbie H, Myers K, Stapleton J, Dhanji A. Is Varenicline Effectiveness Declining in Randomized Trials?—Reply. Arch Intern Med. 2011;171(19):1770-1772. doi:10.1001/archinternmed.2011.494