Twenty-year trends in benzodiazepine dispensing in the Australian population.
OBJECTIVE
Considerable concern has been expressed about overprescribing of benzodiazepines and related harms. Past analyses have relied on World Health Organization-defined daily doses (DDD) which are sometimes out of keeping with clinical usage. This study examines 20-year (1992-2011) trends of benzodiazepine dispensing in Australia using both DDD and Ashton equivalent dose.


METHODS
Data from the Drug Utilisation Sub-Committee and the Pharmaceutical Benefits Scheme (PBS) website were analysed. Trends in number of prescriptions, DDD/1000 people/day and DDD/prescription were examined over time, and between states/territories.


RESULTS
In the 20-year period, 174 080 904 scripts were recorded, with temazepam the most dispensed benzodiazepine (35% of scripts), followed by diazepam (23%). Overall recorded utilisation fell from 27.7 DDD/1000 people/day in 1992 to 20.8 in 2011 (24.9% decrease). There were striking changes in use of individual benzodiazepines over time, with reductions in oxazepam and flunitrazepam and dramatic increases in alprazolam. Since 1998, there has been a steady increase, albeit modest, in per script DDD. The DDD/1000 people/day for items dispensed through PBS/Repatriaton-PBS was highest in Tasmania and lowest in Northern Territory.


CONCLUSIONS
Despite a modest overall decline in the amount of benzodiazepine dispensed, the level of use is still likely to reflect relative over-prescribing given the paucity of accepted indications for long-term use. Since 1998, there was a polynomial increase in quantity dispensed per script. The WHO-defined DDD for clonazepam seems inappropriate and could impede monitoring of its abuse. Other problems include lack of national data for medications not subsidised on PBS/Repatriation PBS. A broad policy approach is required, not one which targets only one particular benzodiazepine.
Australian Primary Health Care Research Institute, Australian National University, Canberra, ACT, Australia.
M M
MM
Islam
K M
KM
Conigrave
C A
CA
Day
Y
Y
Nguyen
P S
PS
Haber
D001315:Australia; D001569:Benzodiazepines / Q000627:therapeutic use*; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D004363:Drug Utilization / Q000639:trends*; D006801:Humans; D057970:Inappropriate Prescribing / Q000706:statistics & numerical data; D007356:Insurance, Pharmaceutical Services / Q000706:statistics & numerical data; D012189:Retrospective Studies; D013810:Therapeutic Equivalency
D001569:Benzodiazepines
Ashton equivalent dose; anxiolytic drug; benzodiazepine; defined daily dose; hypnotic; sedative