Smoking is the leading cause of preventable morbidity and premature death in the UK and internationally (Peto et al., 2000) and costs the National Health Service around £5 billion annually, therefore smoking cessation aids are important for those wishing to quit.
The most clinically effective drug for short term abstinence in smoking cessation is Varenicline (Cahill et al., 2013), which was licensed in the UK in 2006. Concerns about the drug’s neuropsychiatric safety led to issued warnings from the Medicines and Healthcare Products Regulatory Agency (MHRA) in 2008 (MHRA, 2008) and in 2009 the United States Food and Drug Administration (FDA) has required the black box warning (the strongest safety warning) to the labelling of varenicline (FDA, 2009).
A recent meta-analysis (Gibbons & Mann, 2013) found no evidence of an increased risk of depression, suicide or non-fatal self-harm (see Fluharty, 2014). However, a criticism raised was that this study was sponsored by industry and there is evidence that industry sponsored trials may report outcomes favourable to the study sponsor (Etter et al., 2007).
To provide a comprehensive evaluation Thomas and colleagues (2015) conducted a systematic review and meta-analysis to determine the risk of neuropsychiatric adverse events and death in all published randomised placebo controlled trials of varenicline.