Previous studies have linked benzodiazepines -- a medication class that may be used in chronic obstructive pulmonary disease (COPD) to treat symptoms of insomnia, depression, anxiety and shortness of breath -- with adverse outcomes, but until now there has been little information on how frequently it's prescribed or who is using it.

COPD, also known as emphysema or chronic bronchitis, is most commonly caused by smoking in North America and is estimated to affect 5 to 10 per cent of the Canadian population. American Thoracic Society-European Respiratory Society guidelines recommend that benzodiazepines be avoided in these patients because of potential respiratory-related side-effects.

Dr. Nicholas Vozoris is the lead author of a study published this week in Drugs and Aging looking at the scope of benzodiazepine use in the older adult COPD population to determine just how many people are using the drug.

"I see a large number of COPD patients taking this medication class to help relieve disease-related symptoms like insomnia, depression and anxiety," said Dr. Vozoris, a respirologist at St. Michael's Hospital. "But considering the potential respiratory side-effects, and the well-documented neurocognitive side effects like memory loss, decreased alertness, falls and increased risk of motor vehicle accidents, the high frequency of benzodiazepine use in COPD is very concerning."

Dr. Vozoris and colleagues looked at more than 100,000 adults 66 years and older with COPD in Ontario between 2004 and 2009 to see how many new benzodiazepines were dispensed and the severity of each patients' COPD while on the drug.

The results found that new benzodiazepine dispensing was common and occurred in more than a third of the adults. Use of the drugs was 40 per cent more common amongst those with more severe COPD. This group also had the highest number of repeat prescriptions and early refills and benzodiazepines were also commonly dispensed to patients while they were having flare-ups of the disease.

"These findings are new and they are concerning because they tell us that the patients most at risk to be affected by the adverse effects of this drug are the same ones that are using it with the most frequency," Dr. Vozoris said. "This medication could be causing harm in this already respiratory-vulnerable population."

Although benzodiazepines can be effective for helping patients sleep, this medication class has been previously found to affect breathing ability and oxygen levels at night.

"Patients need to hear this and health care providers need to give thought into who they are prescribing this medication class to," Dr. Vozoris said. "We're talking about a very vulnerable sub-group and we may be inappropriately prescribing this medication class to those patients."

The study was funded by the Canadian Institutes of Health Research Institute of Nutrition, Metabolism and Diabetes.