J Popul Ther Clin Pharmacol 2019 Jan 22;26(1):e22-e38. Epub 2019 Jan 22.
College of Pharmacy, University of Manitoba.
Purpose: 1) To evaluate trends for benzodiazepines (BZD) and Z-Drugs over 15-years in a general Canadian adult population measured by: a) consumption b) pharmacologic exposure c) dose intensity and d) prevalence of use. 2) To demonstrate the utility of Diazepam Milligram Equivalence (DME) based measurements when used in conjunction with traditional standard measurements of drug utilization such as the Defined Daily Dose (DDD) system.
Methods: Administrative data covering all prescriptions from April 2001-March 2016 for BZD and Z-Drugs for patients ≥18 years was used. Consumption was calculated as DDD/1000-person days. Dose intensity (DI) was determined by conversion of individual daily doses to Diazepam Milligram Equivalents (DME). Pharmacologic exposure (PE) was calculated as DME-DDD/1000-person days. Prevalence was determined as the proportion of the adult population with receipt of ≥1 prescription in a given year. Changes were assessed using either Poisson or simple linear regression at an alpha of 0.05.
Results: Z-Drug usage (~99% zopiclone) statistically increased on every measure over the course of the study period; consumption (8.2 to 28.6 DDD/1000-person days), PE (4.1 to 14.3 DME-DDD/1000-person days), DI (5.0 to 5.43 DME/day) and prevalence (2.0% to 4.8%). For BZD the only statistically significant changes were in DI (17.1 to 20.1 DME/day) and prevalence (9.3% to 8.1%). Consumption and PE gradually increased from 2001 to 2011 for BZD before declining thus producing a non-significant trend for BZD.
Conclusion: 1) Z-Drug usage increased markedly from 2001 to 2016 whereas BZD use only increased in terms of DI. 2) DME-based measurements enable further interpretation of BZD utilization compared to sole reliance on DDD.