Projected increase in amyotrophic lateral sclerosis from 2015 to 2040

Introduction

According to the United Nations, the number of individuals in the world above age 60 is expected to increase rapidly. This ageing pattern is especially significant in developing countries, where the proportion of older individuals will increase from about 9% in 2015 to 16% by 2040 (ref. 1). The number of individuals diagnosed with chronic disease has grown due to this trend2. For instance, one study found that the number of individuals with Parkinson’s disease will double between 2005 and 2030, and the weight of disease will shift from developed nations to developing nations3. While similar studies have been conducted on other diseases4,5, no such study has sought to project the number of amyotrophic lateral sclerosis (ALS) cases.

ALS is the most common adult-onset motor neuron disease. It is characterized by both upper and lower motor neuron degeneration and has a median survival of 2–4 years6. The worldwide annual incidence of ALS is about 1.9 per 100,000 (ref. 7), with uniform rates in Caucasian populations and lower rates in African, Asian and Hispanic populations8. Although rare, the socioeconomic significance of the disease is substantial9,10. Accurate projections of ALS case numbers will help guide healthcare policy and the effective allocation of resources.

The objective of our study is to estimate the number of individuals with ALS across the globe in the years 2015 and 2040. To do this, we use previously published data on the incidence of ALS. We show that the number of cases of this fatal neurodegenerative disease will increase by 69% over the next 25 years and that this increase is primarily due to population ageing. We further demonstrate an overall shift in the projected number of ALS cases away from developed countries towards more developing nations.

Results

Population and ALS prevalence estimates

We identified ALS incidence studies for 10 countries and geographical regions (China, Europe, Iran, Japan, Libya, New Zealand, Serbia, Taiwan, the United States and Uruguay) that were suitable for analysis. The total population of these countries in 2015 was 2.46 billion, representing 34% of the world population. The total population of the countries above age 20 will increase by 7.7% from 1.89 billion in 2015 to 2.03 billion in 2040.

The prevalence rates of ALS were highest in Uruguay, New Zealand and the United States, and lowest in Serbia, China and Taiwan (Supplementary Tables 1 and 2). The age groups with the highest prevalence rates of ALS were from age 60 to 79.

Estimates of ALS case numbers in 10 regions

In 2015, there were 45,810 men and 34,352 women diagnosed with ALS in the 10 regions for which incidence rates were available. The projected number of individuals with ALS in 2040 was 60,394 men and 45,299 women. Thus, the total number of individuals with ALS is expected to grow from 80,162 in 2015 to 105,693 in 2040, representing an increase of >31% (Table 1). The geographical distribution of this increase in case numbers is shown in Fig. 1.

Table 1: Projected number of ALS cases classified by country and year.

Full size table

Figure 1: Projected increase in the number of individuals with ALS from 2015 to 2040.

The countries studied are shown in light blue. The bars represent the growth in number of cases from 2015 (royal blue) to 2040 (navy). The per cent increase in cases during this time is shown under the country’s name. The map was created in R using the packages maps, ggplot2 and ggsubplot (available at https://cran.r-project.org/).