Impact of increasing the re-supply interval on the seasonality of subsidised prescription use in Australia.
OBJECTIVE
To evaluate the impact of increasing the minimum re-supply period for prescriptions on the Pharmaceutical Benefits Scheme (PBS) in November 1994. The intervention was designed to reduce the stockpiling of medicines used for chronic medical conditions under the PBS safety net.


METHODS
Interrupted times series regression analyses were performed on 114 months of PBS drug utilisation data from January 1991 to June 2000. These analyses assessed whether there had been a significant interaction between the onset of the intervention in November 1994 and the extreme levels of drug utilisation in the months of December (peak utilisation) and January (lowest utilisation) respectively. Both serial and 12-month lag autocorrelations were controlled for.


RESULTS
The onset of the intervention was associated with a significant reduction in the December peak in drug utilisation; after the introduction of the policy there were 1,150,196 fewer prescriptions on average for that month (95% CI 708,333-1,592,059). There was, however, no significant change in the low level of utilisation in January. The effect of the policy appears to be decreasing across successive post-intervention years, though the odds of a prescription being dispensed in December remained significantly lower in 1999 compared to each of the pre-intervention years (11% vs. 14%).


CONCLUSIONS
Analysis of the impact of increasing the re-supply period for PBS prescriptions showed that the magnitude of peak utilisation in December had been markedly reduced by the policy, though this effect appears to be decreasing over time. Continued monitoring and policy review is warranted in order to ensure that the initial effect of the intervention be maintained.
Donnelly
N
N
National Drug & Alcohol Research Centre, University of New South Wales.
McManus
P
P
Dudley
J
J
Hall
W
W
D001315:Australia; D016001:Confidence Intervals; D003625:Data Collection; D011307:Drug Prescriptions / Q000191:economics* / Q000706:statistics & numerical data*; D004363:Drug Utilization / Q000639:trends*; D005260:Female; D005380:Financing, Government; D006801:Humans; D007356:Insurance, Pharmaceutical Services / Q000191:economics* / Q000706:statistics & numerical data; D008297:Male; D011336:Probability; D012044:Regression Analysis; D012621:Seasons; D012680:Sensitivity and Specificity; D013997:Time Factors