Use of benzodiazepines and related drugs in Manitoba: a population-based study.

BACKGROUND

Despite their favourable toxicology profile, benzodiazepines and the related Z-drugs (zopiclone, zolpidem and zaleplon) have been associated with physiological tolerance, dependence and addiction. Evidence of harm (e.g., falls, motor vehicle collisions and cognitive disturbances) has been reported in older populations. The aim of this study was to determine the relation between users' characteristics and the use of benzodiazepines and Z-drugs in Manitoba over a 16-year period.

METHODS

This time-series analysis was based on prescription data from Apr. 1, 1996, to Mar. 31, 2012, obtained from the Drug Product Information Network database of Manitoba. We obtained sociodemographic information on benzodiazepine and Z-drug users from the Population Registry and determined changes in utilization rates over time using generalized estimating equations.

RESULTS

Overall, the prevalence of benzodiazepine use remained stable at about 61.0 per 1000 population between 1996/97 and 2011/12; however, the prevalence of Z-drug use increased steadily from 10.9 to 37.0 per 1000 over the same period. In older people (≥ 65 years), the incidence of benzodiazepine use decreased from 55.5 to 30.3 users per 1000, whereas the incidence of Z-drug use increased from 7.3 to 20.3 users per 1000 over the study period. Among those 18-64 years of age, the incidence of benzodiazepine use decreased from 30.1 to 27.6 users per 1000, but the increase in incidence of Z-drug use was more than 2-fold. The youngest population (≤ 17 years) showed the lowest rates of use of these drugs. The highest rates of use were observed among older women and the low-income population.

INTERPRETATION

Over the study period, benzodiazepines have been prescribed less frequently to older patients in Manitoba; however, zopiclone prescribing has continued to increase for all age groups. The reasons for this increase remain to be determined.