Dr Ruth Leadbetter (NZBRI), Dr Deborah Mason (NZBRI) and co-authors have published a study on multiple sclerosis mortality in New Zealand in the Journal of Neurology, Neurosurgery and Psychiatry. They studied the life expectancy and risk of dying in New Zealanders with MS compared to the general population. Their results show that people with MS can expect to live a long life, close to that of the general population. The life expectancy for people with MS is expected to improve even further in the near future.
A summary of the study and an article written by Cosmos magazine on the findings can be found at https://cosmosmagazine.com/health/multiple-sclerosis-ms-life-expectancy/. A link to the full paper can be found at: https://jnnp.bmj.com/content/early/2023/03/06/jnnp-2022-330582.
The following has been written by Dr. Ruth Leadbetter:
We have recently published the results of our New Zealand Multiple Sclerosis (MS) mortality study. This showed that New Zealanders with MS can expect to live a long life with a life expectancy nearing that of the general population. This is the first nationwide study on MS mortality from the southern hemisphere in the last 30 years. Most research in this area before our study, has only looked at people with MS in Europe and North America.
In our study, we investigated the life expectancy and mortality rates (or risk of dying) in New Zealanders with MS compared to the general NZ population. We studied the survival of people with MS who had taken part in the NZ MS Prevalence study in 2006. In the Prevalence study, every person with MS living in NZ at the time of the census was recruited and there were just under 3000 participants. We obtained ethics approval for this mortality study and used anonymised data. We established which people from the Prevalence study were deceased after 15 years, in March 2021, and their ages at death. We then matched each person with MS with a hypothetical New Zealander of the same age, year of birth and sex from life table data from Statistics New Zealand. We were able to compare the life expectancy of our group of people with MS with the expected life expectancy of someone similar without MS. We also compared the numbers or rates of deaths between the two groups.
In our study, people with MS had a median life expectancy of 79.4 years compared to 86.6 years for someone similar without MS. The difference in life expectancy was only 7.2 years and this is in an MS group who had lived most of their life before the highly effective treatments we now have for MS were available. The difference we found in life expectancy is very similar to what has been seen in recent overseas studies which report a difference of 6-9 years between people with MS and the general population. We also found that people with MS have overall, twice the risk of dying than the average New Zealander. This is also similar to other countries where the mortality risk (or overall risk of dying) is calculated to be 2-3 times the risk of the general population.
When we looked more closely at the different characteristics of people with MS, we found that those with a progressive form of the disease from the start had a lower life expectancy than those who started with a relapsing-remitting form. We also found that those people who had started experiencing MS symptoms earlier in life had a lower life expectancy and higher risk of dying than people who developed the disease later. In our study group, people with MS who first had symptoms in their 20s had a life expectancy that was almost 10 years lower than the general population.
Our data show an improvement in the numbers of deaths (or excess death rates) in New Zealanders with MS over time. Those people who had been diagnosed in the late 1990s or early 2000s had half the numbers of deaths of those who were diagnosed in the 1960s or 70s. We believe there are a number of factors which have led to an improvement in survival for people with MS over those years, including better medical care such as treatment of infections and access to rehabilitation. Treatment of MS has improved significantly even since the Prevalence study group were enrolled. We now have highly effective treatments available which we expect will improve the life expectancy of people with MS further.
This study is an important first step in understanding the difference in life expectancy and survival of New Zealanders with MS compared to the rest of the population. We hope these results provide valuable information to help plan healthcare initiatives and resource allocation for New Zealanders with MS. Our next study will be looking more closely at the causes of death in MS to better understand what is causing this difference in life expectancy and to identify aspects of the disease that we could target to improve the survival of New Zealanders with MS.
This study was funded by the VJ Chapman grant from the Neurological Foundation and the Neurology Trust.