Hyperphenylalaninaemia due to tetrahydrobiopterin (BH4) deficiency, sapropterin, June 2019
Page last updated: 1 November 2019
Drug utilisation sub-committee (DUSC)
June 2019
Abstract
Purpose
To compare the predicted and actual utilisation of sapropterin since PBS listing on
1 May 2014. In its recommendation, the Pharmaceutical Benefits Advisory Committee
(PBAC) requested that the Department review the utilisation of sapropterin after five
years of its first listing to examine the number of patients continuing on this therapy.
Date of listing on the Pharmaceutical Benefits Scheme (PBS)
Sapropterin was listed on the PBS on 1 May 2014.
Data Source / methodology
- PBS pharmacy claims data from the Department of Human Services (DHS) prescription database.
Key Findings
- Majority of patients (94%) who had initiated on sapropterin between Years 1 to 4 of listing were continuing to be supplied sapropterin, including all patients who initiated therapy in the first year of listing (1 May 2014 to 30 April 2015).
- The number of actual patients treated with PBS subsidised sapropterin in the first two years of listing was similar to predicted. However, the actual number of patients exceeded the number of patients predicted from Year 3 onwards. Actual patient numbers were xxxx%, xxxx% and xxxx% higher than predicted in Years 3, 4 and 5, respectively.
- The total number of prescriptions of sapropterin supplied was less than predicted in the first two years of listing. The number of prescriptions were xx% and xx% higher than predicted in Year 4 and 5 respectively.
- The greater than predicted number of patients and prescriptions in the later years did not translate to greater than predicted PBS & RPBS (R/PBS) expenditure because there was:
- a lower than expected number of prescriptions dispensed per patient per year; and
- a lower than expected number of dispensed pack quantity per patient per year.
The lower than expected number of prescriptions and dispensed pack quantity could be due to the following:
- A higher than expected proportion of prescriptions dispensed at less than the maximum quantity;
- A lower than expected dose supplied due to dose titration, particularly in older patients, to achieve individualised targets of blood phenylalanine level.
