Statistics about Amyotrophic Lateral Sclerosis (ALS)
Ethnicity is an important factor when analyzing statistics on amyotrophic lateral sclerosis (ALS) data because some studies suggest that ethnic background may modify predisposition to ALS. However, it is widely accepted that the incidence of ALS is uniform across populations of Caucasian origin or most people in Western Europe and North America (USA and Canada). The same is the case with other motor neurodegenerative diseases.
ALS incidence (the No. of people getting ALS each year per 100,000)
Most studies on Caucasian populations have shown an incidence of ALS above 1 per 100,000 person years. In other words, each year there is on average a 1:100000 chance of getting ALS. The highest reported incidence in a Caucasian population is 2.4 per 100,000 and the lowest incidence is 0.6 per 100,000. These numbers are however averaged numbers for whole populations and from birth to death of individuals.
According to studies made on other ethnic populations, the incidence of ALS is lower among non-caucasian populations. This can however be disputed as the criteria of diagnosis and the frequency of which ALS cases are reported may be different in some of those countries.
It is more relevant to look at incidence rates for those age-groups affected by ALS and not just total populations.
Secondly, meaningful comparisons between studies (meta-analysis) can only be made if the data are somehow adjusted for age and sex and compared to a population standardized to meet certain criteria. This was done in a study in Neurology by Cronin et al. (2007).
Here all data were adjusted to fit into an age group from 45 years to 74 years. This seems reasonable as the vast majority of people diagnosed with ALS are older than 45 but younger than 74 years old.
The study showed incidence rates of ALS in some of the world’s largest countries (table 1).
| Country / Region | Male | Female | Overall | 5% CI |
| United States (WA) | 5.3 | 4.9 | 5.1 | 4.3 - 6.1 |
| United States (MN) | 7.1 | 6.0 | 6.6 | 4.5 - 9.6 |
| United States (TX) | 3.4 | 3.2 | 3.3 | 2.7 - 4.0 |
| Canada | 6.7 | 4.2 | 5.3 | 3.3 - 8.1 |
| Japan | 3.4 | 3.2 | 3.3 | 2.7 - 4.0 |
| Greece | 3.1 | 1.8 | 2.4 | 1.5 - 3.7 |
| Denmark | 5.0 | 3.6 | 4.2 | 3.1 - 5.7 |
| Finland | 7.4 | 8.9 | 8.2 | 5.0 - 12.7 |
ALS prevalence (the no. of people living with ALS per 100,000)
As a rule of thumb only 50% of those diagnosed with amyotrophic lateral sclerosis survive for more than 3 years. The life-expectancy following diagnosis depends on a number of factors such as age and physical condition. Age is perhaps the most important factor of the two; younger individuals of course tend to survive for a longer period of time than elderly.
If the prevalence is compared with the incidence, the higher ratio of prevalence to incidence (prevalence:incidence) the longer period of time people are living with the condition.
In other words: prevalence = incidence . average duration.
The study by Cronin et al. 2007 did not consider the prevalence of ALS. It did however considered the mortality from ALS – that is the incidence of death from ALS. Theoretically speaking, the mortality should be close to the incidence.
Local differences in the way deaths are reported make comparisons between mortality and incidence difficult as the way death are reported are different from country to country. In some cases the cause of death is registered than something else than ALS – even though the condition was caused by ALS.
Data were however analysed and showed that the overall mortality from ALS in the United States is 1.0 per 100,000 a year. In Japan it is 0.7 per 100,000, in Denmark 0.9 and in Canada 1.5. In all European countries the mortality was in the range 0.7 to 1.5 per 100,000.
References
Cronin S., Hardiman O., Traynor B.J, Ethnic variation in the incidence of ALS – a systematic review, Neurology 68, pp. 1002-1007, 2007
Web references about ALS statistics
It is difficult to find pages about ALS statistics but here are a few.
Short statistics section at the ALS Center
Statistics at Wrongdiagnosis
MND alliance resource about ALS statistics (pdf)
ALS MND support forum - includes some statistics