4.3 Estimation of changes in use and financial impact of other medicines

Page last updated: September 2016

4.3.1   Identify PBS medicines likely to be affected

If using a market-share approach, PBS-listed medicines that are likely to be substituted by the proposed medicine will have been identified in Subsection 4.2.2. However, identifying other PBS-listed medicines that will increase or decrease in usage may still be relevant.

PBS-listed medicines likely to be affected by the listing of the proposed medicine include:

• PBS-listed medicines substituted by the proposed medicine
• other PBS-listed medicines with decreased usage
• other PBS-listed medicines with increased usage.

List all PBS-listed medicines that fall into each of these three categories. Include the PBS-listed medicines identified as comparators in Subsection 1.1 and as other relevant therapies in Subsection 1.2, and disaggregate by form and strength. Where the proposed medicine is replacing a medical procedure or has no comparator medicine, or where patients are receiving best supportive care in the absence of the proposed medicine, there will be no substituted medicines.

If there is potential for market growth or an increase in eligible patients because of listing the proposed medicine, nominate whether these patients are likely to have been taking another medicine. State and justify any medicines that are to be replaced for the proportion of patients that represent market growth.

PBS-listed medicines with expected decreased usage after the listing of the proposed medicine include those that are:

• co-administered with substituted medicines
• used to treat adverse reactions to substituted medicines
• used to treat the clinical end points that might be reduced after therapy involving the proposed medicine.

PBS-listed medicines with expected increased usage after listing of the proposed medicine include those that are:

• co-administered with the proposed medicine
• used to treat adverse reactions to the proposed medicine.

The impact of adverse reactions might have less weight if the evidence shows that they are of insufficient clinical importance to require management with PBS-listed medicines, or if they are similar for the proposed medicine and its major competitors. Note if there is insufficient information available from trial results or extended assessment of comparative harms to include the impact of adverse reactions on PBS expenditure.

4.3.2   Change in the units dispensed over six years

If using an epidemiological approach, discuss the extent of change for each of the forms and strengths of PBS-listed medicines that will be substituted, and for those that are expected to increase or decrease in usage after listing of the proposed medicine. Present and justify the change in the units for each of these medicines over six years. Reference how the estimates were generated and the data on which the estimates are based. Present estimates by beneficiary type, as described in Subsection 4.2.3.

Section 3 may incorporate a change in PBS-listed medicines because of listing the proposed medicine. Justify any inconsistencies between Sections 3 and 4 in terms of the identified medicines or the estimated extent of change of usage over the six years following listing of the proposed medicine.

If using a market-share approach, the change in the units for substituted PBS-listed medicines will represent the market share lost to the proposed medicine. State and justify the proportion of the market gained by the proposed medicine and lost by each substituted PBS-listed medicine in Subsection 4.2. Justify any estimates of a different rate of substitution across different PBS-listed medicines, particularly where there is differential pricing across the PBS-listed medicines.

Estimates disaggregated according to beneficiary type

Base any disaggregation into proportions for the PBS and the RPBS, and by beneficiary type on the most recent 12 months of usage data from Services Australia. If the expected substitution is for a distinctive subgroup of current use of the substituted medicine(s), base the disaggregation on the subgroup.

Use the relevant spreadsheet of the standardised Excel workbook to calculate the results of this subsection.

4.3.3   Financial impact over six years

Based on estimated utilisation changes, estimate the financial impact in each year over six years for each of the forms and strengths of each medicine substituted, decreased and increased. Refer to Subsection 4.2 for the suggested approach. Present the disaggregated and aggregated costs, applying both the DPMQ or the DPMA, and the DPMQ or the DPMA with appropriate patient copayment subtracted, as per Subsection 4.2.

Use the relevant spreadsheet of the standardised Excel workbook to calculate the results of this subsection.