Abstract
Aims: Oral isotretinoin is an effective treatment for severe acne that is teratogenic. On 1 March 2009 funded access to oral isotretinoin in New Zealand was extended from dermatologist-only to also include prescriptions written by other prescribers where a dermatologist, vocationally registered general practitioner (GP) or nurse practitioner had obtained a Special Authority for this patient and medication. At the time of the change the Pharmaceutical Management Agency (PHARMAC) funded the development of an electronic decision support tool for primary care to support the safe prescribing and use of isotretinoin. Regular review of health outcomes was recommended to ensure the widening of funded access did not have negative effects on the health of the population.
This study aimed to examine the previously identified inequitable isotretinoin access to determine if the change in funded prescriber influenced isotretinoin dispensing by ethnicity, age, gender, or deprivation level. The study also investigated terminations of pregnancy (TOPs) and potentially exposed live births following isotretinoin dispensing in women with different prescriber-types and compared these rates in women for whom the prescriber used the Best Practice Advocacy Centre (BPAC) isotretinoin decision support tool to support their prescribing with the rates in women whose prescriber did not.
Methods: Retrospective prescription data for the 8 years from 1 March 2007 to 1 March 2015 were analysed to determine how access to isotretinoin changed in the twelve month periods before and after the funding change. Using National Health Index (NHI) codes, maternity outcomes for women who had isotretinoin dispensed during the study period were analysed with regard to TOP and exposed live births. The rates of these adverse maternity outcomes were then compared for different prescriber-types and for women whose clinician used the BPAC decision support tool to guide their prescribing.
Results: The use of isotretinoin has continued to increase since the change in funding and people living in more deprived areas (as defined by the NZDep Index), and Maori, Pacific and Asian people have had a proportionally larger increase in numbers accessing isotretinoin. General practitioners (GPs) now prescribe more isotretinoin than dermatologists.
The TOP and exposed live birth rate following isotretinoin prescription is similar in women prescribed the drug by dermatologists and GPs. These clinicians prescribe the majority of isotretinoin in New Zealand and the rate of TOP within six months of an isotretinoin prescription is around 16-23% of that for all females aged 15-44 in New Zealand. However the female patients of other clinicians who prescribe isotretinoin much less frequently than dermatologists or GPs have TOPs within six months of isotretinoin at higher rates. Up to 16 live births per year in New Zealand are potentially exposed to isotretinoin with dermatologists, GPs and other clinicians all prescribing for the women involved. Use of the BPAC decision support tool to guide the prescribing of isotretinoin resulted in a lower rate of TOP and exposed births than occurred in patients where it was not used.
Conclusions: Isotretinoin is proportionally more accessible to Asian, Maori and Pacific people and people in lower socio-economic groups than it was when funded only through dermatologists. However Europeans and the least deprived groups continue to be the people who use isotretinoin in the greatest numbers.
GPs are now the largest group of isotretinoin prescribers in New Zealand but this has not resulted in higher rates of TOP or potentially exposed pregnancies than when prescribing was funded only through dermatologists. However female patients of other prescribers, who do not prescribe isotretinoin as frequently, have higher rates of TOP following isotretinoin dispensing and more potentially exposed live births.
The BPAC Decision Support tool helped achieve better maternity outcomes for women accessing isotretinoin where it was used to guide prescribing. The challenge for health managers is to address barriers to its use, to invest in supporting all isotretinoin prescribers to use decision support, and to involve female patients in adhering to contraceptive guidelines.