Antianxiety and Hypnotic Drugs Up Mortality Risk

Antianxiety and hypnotic drugs were linked to a significantly increased risk of mortality in a recent large, retrospective cohort study from the United Kingdom.

“This study adds to the growing weight of evidence showing that these are dangerous drugs,” explained lead author Dr. Scott Weich, Professor of Psychiatry, Division of Mental Health and Wellbeing, Warwick Medical School, University of Warwick, Coventry, West Midlands, United Kingdom, in an e-mail to Consultant360. “We’ve known for many years that benzodiazepines are addictive, and that they have long-term effects on memory and concentration in particular. But more recently it has been shown that they are also associated with increased rates of death. Like previous studies, we found that this risk increased with the amount of exposure to these drugs.”
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Other research on the relationship between these agents and mortality has reported varying effect sizes. In addition, Weich pointed out that their study differs from previous research in that they obtained prescription data from prescribing records rather than by participant self-report and they included all anxiolytic and hypnotic drugs in the analysis regardless of the reason for their prescription, whereas some studies only included agents prescribed for anxiety or insomnia.

Finally, an important difference is the fact that this study controlled for a comprehensive list of potential physical and psychiatric confounders, including sex, age at study entry, sleep and anxiety disorders, other psychiatric disorders, prescriptions of other nonstudy drugs, and medical morbidity, among others.

Weich and colleagues analyzed data from the General Practice Research Database involving 34,727 patients who received prescriptions for anxiolytic and/or hypnotic drugs between 1998 and 2001. Participants, who were aged 16 years or older when they were first prescribed the drugs, were matched with 69,418 control patients and were followed for an average of 7.6 years.

Benzodiazepines were the most commonly prescribed drugs. The authors noted in the study that co-prescribing was common; over 76% of individuals in the drug group were prescribed a benzodiazepine, nearly 39% were prescribed a Z drug (zaleplon, zolpidem, and zopiclone), and 33.5% were prescribed one or more of the other study drugs.

Researchers found that patients who took these agents had an approximate doubled risk of death after adjusting for the potential confounders.

“We have to be cautious in drawing conclusions from this study, since observational research can never be conclusive or prove causal relationships,” said Weich. “But if all of the studies [on this topic] are looked at together, a consistent picture of harm emerges. The reason this matters so much is because of the very large numbers of prescriptions that are written for these drugs every year.”

According to Weich, the next steps are further research that is “sufficiently powered to look at associations with specific types of morbidity (eg, cancer, respiratory illnesses, and dementia) as well as cause of death. Although it is often argued that observational research can never elucidate causal associations (which is true), more experimental forms of research (like clinical trials) are both unfeasible and unethical (as well as prohibitively expensive) in the investigation of associations between these drugs and mortality.”

This study was published in BMJ.

-Meredith Edwards White

Reference

Weich S, Pearce HL, Croft P, et al. Effect of anxiolytic and hypnotic drug prescriptions on mortality hazards: retrospective cohort study. BMJ. 2014 Mar 19;348:g1996. doi: 10.1136/bmj.g1996.