No scientific evidence of risks linked to smoking cessation drug
The smoking cessation drug varenicline has been reported to increased risks of suicidal behaviour, traffic accidents and violence, amongst other things. However, a new registry study from Karolinska Institutet and Oxford University now shows that there is no good scientific evidence for such adverse events due to the drug. The findings are being published in the BMJ.
Varenicline (trade name Champix) was introduced to the market in 2006, and is today widely prescribed for the treatment of nicotine dependence. At the same time, reports that the drug may be linked with increased risks of suicidal behaviour, depression, psychoses and violence have led regulatory agencies in Europe and the US to issue warnings. Varenicline use has also been restricted or prohibited for several transportation industry professions, including pilots, air traffic controllers, truck and bus drivers, and certain military personnel, due to reports of increased traffic accidents.
The current study is based on 69,757 individuals in Sweden aged 15 or above, who were prescribed varenicline between 2006 and 2009. The research team examined associations between the use of varenicline and a range of adverse outcomes, such as suicidal behaviours, depression, criminal offending, transport accidents, traffic-related offences, and psychoses. They adjusted carefully for known risk factors such as age, sex and pre-existing psychiatric disorders, and performed a novel analysis by examining rates of adverse outcomes in the same person during periods of medication and non-medication. National registers were used to collate information on criminal convictions, psychiatric conditions, suicidal behaviour, transport accidents and traffic offences, and substance abuse.
Pre-existing psychiatric disorders
The results show that varenicline was not associated with significant increases in suicidal behaviour, criminal offending, transport accidents, traffic offences, or psychoses. A small increased risk of mood and anxiety conditions during periods of medication was found, however, in individuals with pre-existing psychiatric disorders, which the authors say “requires confirmation using other study designs.”
“Overall, our results suggest that previous reports linking the use of varenicline to several adverse events may not have taken full account of underlying risk factors, for example concurrent use of other drugs”, comments study co-author Dr Yasmina Molero at Karolinska Institutet’s Department of Medical Epidemiology and Biostatistics. “These findings may also be generalizable to other high income countries like the UK and USA, due to similar prescribing patterns and rates of these outcomes.”
The study was funded with grants from Karolinska Institutet, the Swedish Research Council, FORTE (Swedish Research Council for Health, Working Life, and Welfare), and the Wellcome Trust. Participating investigators are affiliated to the Department of Medical Epidemiology and Biostatistics, and the Department of Clinical Neuroscience, Karolinska Instiutet, and to the Department of Psychiatry at University of Oxford, UK. This news article is an abbreviation of a press release from the BMJ.
View an abstract movie about this research
Varenicline and risk of psychiatric conditions, suicidal behaviour, criminal offending, and transport accidents and offences: population based cohort study
Yasmina Molero, Paul Lichtenstein, Johan Zetterqvist, Clara Hellner Gumpert, Seena Fazel
BMJ 2015;350:h2388, online 2 June 2015, doi: 10.1136/bmj.h2388