Motor neuron disease mortality rates in New Zealand 1992–2013

Abstract

Background: We determined the mortality rates of motor neuron disease (MND) in New Zealand over 22 years from 1992 to 2013. Previous studies have found an unusually high and/or increasing incidence of MND in certain regions of New Zealand; however, no studies have examined MND rates nationwide to corroborate this. Methods: Death certificate data coded G12.2 by International Classification of Diseases (ICD)-10 coding, or 335.2 by ICD-9 coding were obtained. These codes specify amyotrophic lateral sclerosis, progressive bulbar palsy, or other motor neuron diseases as the underlying cause of death. Mortality rates for MND deaths in New Zealand were age-standardized to the European Standard Population and compared with rates from international studies that also examined death certificate data and were age-standardized to the same standard population. Results and Conclusion: The age-standardized mortality from MND in New Zealand was 2.3 per 100,000 per year from 1992–2007 and 2.8 per 100,000 per year from 2008–2013. These rates were 3.3 and 4.0 per 100,000 per year, respectively, for the population 20 years and older. The increase in rate between these two time periods was likely due to changes in MND death coding from 2008. Contrary to a previous regional study of MND incidence, nationwide mortality rates did not increase steadily over this time period once aging was accounted for. However, New Zealand MND mortality rate was higher than comparable studies we examined internationally (mean 1.67 per 100,000 per year), suggesting that further analysis of MND burden in New Zealand is warranted.

Keywords:

• Mortality
• motor neuron disease
• amyotrophic lateral sclerosis
• epidemiology
• New Zealand

Acknowledgements

This publication is dedicated to the patients and families who contribute to our research. We thank Chris Lewis at the Ministry of Health for supplying and advising upon data.

Disclosure statement

The authors declare no conflicts of interest.

The work was supported by Sir Thomas and Lady Duncan Trust, Coker Family Trust, the Hugh Green Foundation, and the Health Research Council of New Zealand. Emma L. Scotter was funded by a Rutherford Discovery Fellowship. Maize C. Cao was supported by a University of Auckland Summer Research Scholarship.

Supplementary material available online

Additional information

Funding

The work was supported by Sir Thomas and Lady Duncan Trust, Coker Family Trust, the Hugh Green Foundation, and the Health Research Council of New Zealand. Emma L. Scotter was funded by a Rutherford Discovery Fellowship. Maize C. Cao was supported by a University of Auckland Summer Research Scholarship.