Motor Neuron Disease Mortality Rates in New Zealand 1992-2013

This study recently examined the rate of MND in New Zealand using mortality (death certificate) data from Statistics Aotearoa.  Previous studies have indicated that there appears to be an unusually high rate of incidence of MND in New Zealand, these studies have been on a regional level which means that this rate can not be extended to estimate the incidence for entire country. Given this lack of information about MND incidence in New Zealand as a whole, national mortality records were sought to infer disease burden and determine whether New Zealand indeed has high or increasing rates of MND. While there are a number of potential shortcomings associated with inferring disease incidence from mortality, the findings supported previous studies that suggest a relatively high MND incidence rate in New Zealand.

It was found that that the proportion of people in NZ who die from MND is higher than any other country that was examined using identical methodology. Whereas the average rate elsewhere is 1.67 deaths from MND per 100,000 people living in the population,  New Zealand’s rate is 2.3-2.8 deaths from MND per 100,000 people living in the population. To ensure the results were able to be compared they were age standardised and only compared to international results that had also been age standardised.

The study also discusses the proportionate mortality which is likely to be a closer reflection of how clinicians perseve the burden of MND as this indicate the proportion of people with MND from a population base of patients who have many different medical  conditions. This ratio demonstrates that death from MND became increasingly likely as other causes of death went into decline.

European countries also tend have higher MND rates. Since approximately 74% of New Zealand’s population is of Caucasian/European descent this may be due to shared ancestry and our population may share genetic and lifestyle risk factors with Europeans. Maori population data showed a lower incidence of MND rate compared to the total population, which could be for several reasons. Further studies may help to determine if unique genetic risk factors are present in our population, and may also shed light on any occupational or environmental factors that are at play.

There is anticipation that the MND patient registry will be able to tell us more about the burden of MND in New Zealand. This registry is New Zealand population based and allows multiple source collection streams for incidence data analysis.

The full article is available here.

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