Lay summary
Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system which causes high levels of disability. Disease-modifying treatments (DMTs) are available to reduce disease progression, although rates of prescriptions are low in Aotearoa and it is not known whether these medications are being prescribed equitably. This activation study will examine the feasibility of using administrative data to identify cases of MS, and to test for ethnic and socioeconomic disparities in access to DMTs. Learnings from this activation study will be adapted for other complex chronic conditions that may be identifiable with administrative data and will inform approaches to classifying those conditions.