MS Incidence Study

History

In New Zealand, only two studies had been undertaken before 2017 to measure the incidence of multiple sclerosis (MS), both are regional, and were conducted between two and four decades ago – thus the true incidence of MS in the country was unknown. In addition, no previous study reported incidence or the rate of conversion from a first demyelinating event (FDE) to MS in a national population, which has lead to a significant knowledge gap of the natural history of early MS.

Study Aims

The specific aims of the study were:

1. To determine the number of people presenting with a first demyelinating event or a new diagnosis of MS between June 1st 2012 and May 31st 2014.
2. To determine the rate of conversion from a first demyelinating event to MS over two years.
3. To determine whether the conversion rate is affected by where you live, (North or South Island) ethnic background or ancestry, as well as lifestyle factors such as smoking.
4. To document the symptoms at the time of the first demyelinating event and any further symptoms at 6, 12 and 24 months.
5. To examine whether the symptoms influence your general health status.
6. To examine whether the symptoms adversely affect your work or schooling at onset and two years.

How will the study be of use?

Knowledge about environmental and lifestyle factors and of the natural history of demyelinating syndromes is essential in order to develop early intervention strategies. The results of this study would help guide doctors in making treatment decisions and provide patients with a clearer idea of their risks of further demyelinating events.

The results have also supported MSNZs advocacy work in pushing for funding for new treatments for the management of MS.

Key Findings

The New Zealand Multiple Sclerosis incidence study began recruitment in 2012. The aim of the study was to identify all persons throughout NZ who were either diagnosed with MS or experienced their first symptoms of demyelination between June 1^st 2012 and May 31^st 2014.

Number of recruits

• 463 were identified and recruited into the study,
• 275 had received a diagnosis of MS
• 188 of whom experienced their first episode of inflammation
• 277 participants 35 (%) were originally recruited as CIS but subsequently diagnosed as MS during the study period
• 317 notifications were also received of persons who didn’t meet the study criteria for reasons such as the symptoms were found not to be due to MS (n=280),  a number received an alternate diagnosis (n=11) or were diagnosed with MS outside the study period (n=26).

The results confirm that NZ continues to be a high risk country for MS with around 134 people diagnosed across the country each year.

Age

The age-standardised incidence (ASI) was 3.3 (95% CI 2.9 – 3.7) per 100,000 population for the entire country. For males the incidence was 1.6 (95% CI 1.2- 2.0) / 100,000 and for females 4.8 (95% CI 4.2 – 5.5) /100,000

Gender

Male to female ratio of 1:3.

Ethnicity

• • 15 people self-identified as Maori. The ASI for Maori was lower than in the overall population at 1.3 (95% CI 0.7- 2.1) per 100,000 population
  • 198 self-identified as NZ European
  • 25 reported other ethnicities of whom two were of pacific island ethnicity
  • 19% were overseas born migrants to NZ with a mean age at migration of 24 ± 14 years.

MS Types

• • 88% were diagnosed with relapsing-remitting MS.
  • 12% were diagnosed with progressive MS

Age

The average age at which people developed their first symptoms was 37.8 +11.8 years. This is older than the average age recorded in previous studies.

Diagnosis Length

The mean age at diagnosis was 42.2 years indicating that there is a significant delay between the onset of first symptoms and diagnosis.

EDSS Score

The mean EDSS at diagnosis was 2.3 ± 1.6.

Latitudinal Gradient

A further objective of the study was to calculate the number of new cases (incidence) of MS by region in order to investigate the relationship between the incidence of the disease and latitude. Residential data obtained at the time of diagnosis showed a 3.8 fold increase in ASI between the northern (36.70S) and southern (45.80S) region of the country.  As shown in Figure 1, MS incidence for the total population increased by 0.68 ± 0.12 per 100,000 population per degree of latitude (p<0.01).

Further information:

Article in the 2014-5 MSNZ Annual Report

List of Published Research papers

New Zealand Brain Research Institute Multiple Sclerosis Research Group 

The Multiple Sclerosis (MS) Research group was formed in 2005 by a collaboration of neurologists and researchers working at Christchurch Hospital and the Universities of Otago and Canterbury.

MS Research Group projects

MS Research Group people

MS Research Group publications