Migrant Investigation of Determinants of Multiple Sclerosis (MIDAS)

MIDAS is a prospective, population-based epidemiological study of Multiple sclerosis (MS) with a nested case-comparison study that will collect data on the clinical, psychosocial and treatment outcomes of new and existing MS patients.

Participants will be enrolled over 24 months for the initial prevalence and incidence estimates and they, or their carer/proxy/guardian, interviewed at three time points: baseline, five years and 10 years following their enrolment.

Issue

MS is an inflammatory disease of the central nervous system that affects an estimated two to three million people worldwide, and is the largest contributor to non-traumatic neurological disability in young adults. Although the immediate cause of MS is unknown, there is strong evidence for complex interactions between genetic and environmental factors. 

It is widely proposed that untimely viral infections in genetically susceptible individuals may induce aberrant immune responses against targets within the central nervous system (CNS), leading to relapsing inflammation but ultimately progressive axonal damage and neurological deterioration through life.   

The most striking epidemiological characteristic of MS is the apparent uneven global distribution of the disease. The ‘latitudinal gradient’ describes a phenomenon of higher prevalence of MS in temperate zones, such as North America and Europe at 50-100 per 100,000, compared to low prevalence in tropical regions at 1-15 per 100,000. 

These data are used to infer genetic, environmental or mixed interactions, but more detailed comparisons of MS risk between populations have proven difficult due to variation in healthcare provision, diagnostics, study methodology and case ascertainment. Indeed, a reappraisal of MS, using incidence as a more reliable measure of population risk, has shown relatively uniform rates across Europe and the United States. 

It is unlikely, therefore, that broad epidemiological comparisons in like populations will identify novel causative factors in MS.

Methods

To provide precise and reliable estimates of the incidence, prevalence and outcome of MS, and to identify differences in the phenotype and potential risk exposures among different ethnic groups in order to elucidate disease trends, aetiological factors, and patterns of health care utilisation for this important disabling neurological disease in adults.

Primary aim

Establish the incidence and prevalence of MS, overall and by birth cohort, gender, major ethnic group socioeconomic status (SES) and migrant status, among residents of the metropolitan region of Sydney, Australia.

Secondary aims

• Determine the associated disability burden, use of medical treatments including modern immunomodulatory agents, and health care utilisation of patients with MS in Sydney.
• Develop a predictive model of disability outcomes accounting for the varied use of modern therapies including immunomodulatory and immunosuppressive drugs.
• Identify demographic, clinical and therapeutic factors associated with good psychosocial and socioeconomic outcomes for people with MS.
• Describe and contrast the phenotypic expression of MS in Chinese/Asian-Australians and other major ethnic groups.
• Identify factors in the environment that influence the susceptibility to, and phenotypic expression of, MS among first-generation Chinese immigrants and their offspring as part of an Australian-Canadian-Chinese collaborative project
• Store serum and DNA for future studies of biomarkers and genetic determinants of MS

Project lead

• Dr John Parratt