Benzodiazepine prescription in Ontario residents aged 65 and over: a population-based study from 1998 to 2013

Abstract

Background: Although commonly used in anxiety and insomnia, recent guidelines recommend caution when prescribing benzodiazepines in the elderly. Here we examined rates of benzodiazepine prescribing to older adults in Ontario, Canada from 1998 to 2013 and impact of legislation that made prescribing regulations more strict.

Method: Annual benzodiazepine prescription rates for Ontario residents aged 65 and over were examined using the Ontario Drug Benefit database which captures all publicly funded prescriptions. Since most drugs, including benzodiazepines, are funded for residents aged ⩾65, data are essentially population-based. Weighted least squares regression methods were used to examine trends in prescribing rates (all benzodiazepines, anxiolytics, hypnotics, short- and long-acting drugs and individual drugs) from 1998 to 2013 for all Ontario residents aged ⩾65 and by sex and 5-year age bands. Impact on monthly prescribing rates of legislative changes (November 2011) which aimed to promote appropriate prescribing and dispensing practices for controlled substances, including requiring prescribers to record specified information, was assessed by constructing an interrupted time-series model.

Results: Benzodiazepines were prescribed to 23.2% of the 1,412,638 Ontario residents aged ⩾65 in 1998, declining to 14.9% of 2,057,899 residents aged ⩾65 in 2013 (p < 0.001 for trend). Rates were significantly greater throughout in older age bands (p < 0.001) and 1.54-1.62 times greater in females than males (p < 0.001). Lorazepam was the most prescribed benzodiazepine throughout, but rates declined from 11.4% in 1998 to 8.5% in 2013. Diazepam rates fell from 2.3% to 0.7%. However, clonazepam prescription rates increased until 2011, 1.7-fold overall. After the November 2011 legal changes, downward shifts were observed in total benzodiazepine prescription rates and for each drug individually. The step function, conditional on covariates, suggested benzodiazepine rates after November 2011 were 2.89 per 1000 (p < 0.001) below rates observed previously, representing a relative reduction of 4.8% compared to the year before the intervention.

Conclusion: Benzodiazepine prescribing rates declined markedly in this population from 1998 to 2013. Targeted legislation may have reduced rates, but the effect, although statistically significant, was small.

Keywords: anxiety; benzodiazepine; insomnia; pharmacoepidemiology; register.

Figure 1.

Percentage of Ontario population aged ⩾65 having at least one benzodiazepine prescription in 1998–2013. (a) Overall and stratified by sex. (b) Stratified by age group.

Figure 2.

Ratio of short-acting (SA) to long-acting (LA) benzodiazepine prescriptions in the Ontario population aged ⩾65 in 1998–2013. (a) Overall and stratified by sex. (b) Stratified by age group.

Figure 3.

Percentage of the Ontario population aged ⩾65 having at least one prescription for each of seven common benzodiazepines in 1998–2013.

Figure 4.

Benzodiazepine prescribing rates to Ontario residents aged ⩾65 by month (number of individuals with one or more prescription over total population aged ⩾65). Note: The red line at November 2011 indicates the point in time of legal changes. Prescription rate reduction by ‘step function’ after this change is 2.89 per 1000 (p < 0.001), a relative reduction of 4.8%.

Figure 5.

Actual benzodiazepine prescribing rates (per 1000 population of Ontario aged ⩾65) by month, for November 2010 to December 2013 and forecast rates by month, for November 2011 to December 2013. Note: Actual prescribing rates are represented by the black line. Forecast rates after November 2011 are represented by the purple line, with 95% confidence intervals around the forecast shaded in gray.