On 2015 Feb 18, Hilda Bastian commented:

This study states as its objective "to determine the efficacy and safety of varenicline" for quitting smoking via smoking reduction. The authors point out that one limitation of the study is its generalizability to a broad population, given its stringent and extensive exclusion criteria. However, it does not stress that both this, and the size of the study, very much preclude this single study "determining" safety of varenicline. The findings in relation to serious adverse events need to be considered in the light of the lower risk for serious adverse events in this study population.

The paper does not refer readers to the safety warnings and concerns about varenicline issued by both the US FDA and European Medicines Agency (EMA), in relation both to psychiatric (FDA boxed warning) and cardiovascular events (FDA, 2012)(see also EMA). (Readers may also be interested in Singh S, 2011 on the issue of cardiovascular events.)

UPDATE: On 9 March 2015, the FDA reviewed safety data on varenicline, retaining the boxed safety warning, and including a warning on interaction with alcohol. However, in March a large meta-analysis found that varenicline increased insomnia and bad dreams, but not depression, suicide, or suicidal ideation (Thomas KH, 2015).

In terms of effectiveness, the authors rightly raise the issue of a lack of direct comparisons between varenicline and others options for smoking reduction. Readers might be interested in Asfar T, 2011, which finds that nicotine replacement therapy (NRT) achieved smoking reduction rates that were not dramatically dissimilar. Cahill K, 2010 found some (inconclusive) evidence that NRT and varenicline result in similar quit rates. Nor are pharmacological means the only successful options for reducing smoking without the risk of serious adverse events.

Note also that this study was funded by Pfizer, manufacturer of the varenicline product marketed as Chantix in the US (Champix in Europe).

On 2015 Feb 18, Hilda Bastian commented:

This study states as its objective "to determine the efficacy and safety of varenicline" for quitting smoking via smoking reduction. The authors point out that one limitation of the study is its generalizability to a broad population, given its stringent and extensive exclusion criteria. However, it does not stress that both this, and the size of the study, very much preclude this single study "determining" safety of varenicline. The findings in relation to serious adverse events need to be considered in the light of the lower risk for serious adverse events in this study population.

The paper does not refer readers to the safety warnings and concerns about varenicline issued by both the US FDA and European Medicines Agency (EMA), in relation both to psychiatric (FDA boxed warning) and cardiovascular events (FDA, 2012)(see also EMA). (Readers may also be interested in Singh S, 2011 on the issue of cardiovascular events.)

UPDATE: On 9 March 2015, the FDA reviewed safety data on varenicline, retaining the boxed safety warning, and including a warning on interaction with alcohol. However, in March a large meta-analysis found that varenicline increased insomnia and bad dreams, but not depression, suicide, or suicidal ideation (Thomas KH, 2015).

In terms of effectiveness, the authors rightly raise the issue of a lack of direct comparisons between varenicline and others options for smoking reduction. Readers might be interested in Asfar T, 2011, which finds that nicotine replacement therapy (NRT) achieved smoking reduction rates that were not dramatically dissimilar. Cahill K, 2010 found some (inconclusive) evidence that NRT and varenicline result in similar quit rates. Nor are pharmacological means the only successful options for reducing smoking without the risk of serious adverse events.

Note also that this study was funded by Pfizer, manufacturer of the varenicline product marketed as Chantix in the US (Champix in Europe).