PURPOSE: Patient co-payments for medicines subsidised under the Australian 
Pharmaceutical Benefits Scheme (PBS) increased by 24% in January 2005. We 
investigated whether this increase and two related co-payment changes were 
associated with changes in dispensings of selected subsidised medicines in 
Australia.
METHOD: We analysed national aggregate monthly prescription dispensings for 17 
medicine categories, selected to represent a range of treatments (e.g. for 
diabetes, cardiovascular diseases, gout). Trends in medication dispensings from 
January 2000 to December 2004 were compared with those from January 2005 to 
September 2007 using segmented regression analysis.
RESULTS: Following the January 2005 increase in PBS co-payments, significant 
decrease in dispensing volumes were observed in 12 of the 17 medicine categories 
(range: 3.2-10.9%), namely anti-epileptics, anti-Parkinson's treatments, 
combination asthma medicines, eye-drops, glaucoma treatments, HmgCoA reductase 
inhibitors, insulin, muscle relaxants, non-aspirin antiplatelets, osteoporosis 
treatments, proton-pump inhibitors (PPIs) and thyroxine. The largest decrease 
was observed for medicines used in treating asymptomatic conditions or those 
with over-the-counter (OTC) substitutes. Decrease in dispensings to social 
security beneficiaries was consistently greater than for general beneficiaries 
following the co-payment changes (range: 1.8-9.4% greater, p = 0.028).
CONCLUSIONS: The study findings suggest that recent increase in Australian PBS 
co-payments have had a significant effect on dispensings of prescription 
medicines. The results suggest large increase in co-payments impact on patients' 
ability to afford essential medicines. Of major concern is that, despite special 
subsidies for social security beneficiaries in the Australian system, the recent 
co-payment increase has particularly impacted on utilisation for this group.