Epidemiology of ALS

Now that we have a foundational understanding of what Amyotrophic Lateral Sclerosis is, this week we will analyze the frequency and distribution of ALS and learn about the specific populations that this disease effects. Many studies have been done and articles have been written on ALS, but in the last five years, a few resources that had overlapping statistics seemed to be most reliable. 

By learning about the epidemiology of the disease, we can educate more people about its prevalence and help people recognize early symptoms and seek treatment and therapy as early as possible. Knowing which populations the disease is most prevalent in can also give certain people a good idea of who to look out for in regards to ALS.

What is the distribution in the US? 

There is a prevalence of 3.9 per 100,000 persons in the US general population, and an incidence of 1.89 per 100,000 per year are diagnosed. Prevalence and incidence are different from each other, where prevalence pertains to known existing cases of ALS, while incidence pertains to the number of new cases diagnosed each year.

Are certain parts of the population more affected than others? 

ALS occurs throughout the world with no racial, ethnic or socioeconomic boundaries. However, overall, ALS is more common among white males (twice as likely African-Americans), non-Hispanics, and persons aged 60-69 years. 

Males have a higher prevalence rate of ALS than females overall (1.5:1).

Age groups with lowest number of persons with ALS were 18-39 years of age and >80 years. Some physicians report that they are seeing "increasing numbers of younger ALS patients," these reports need more study. 

What is the mortality and morbidity from this disease?

Mean age of onset for sporadic ALS is about 60 years. Paralysis is progressive and leads to death d/t respiratory failure within 2-3 years  for bulbar onset cases and 3-5 years for limb onset cases.

About twenty percent of people with ALS live five years or more and up to ten percent will survive more than ten years and five percent will live 20 years. There are people in whom ALS has stopped progressing and a small number of people in whom the symptoms of ALS reversed.

Studies have shown that 70% to 90% of patients diagnosed as having ALS had this condition recorded on their death certificate.

The ALS Association. (2014, January 1). Epidemiology of ALS and Suspected Clusters. Retrieved January 1, 2015, from http://www.alsa.org/als-care/resources/publications-videos/factsheets/epidemiology.html

Mehta, P., Antao, V., Kaye, W., Sandez, M., & Williamson, D. (2014, July 25). Retrieved January 13, 2015, from http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6307a1.htm

Wijesekera, L. C., & Leigh, P. N. (January 01, 2009). Amyotrophic lateral sclerosis.Orphanet Journal of Rare Diseases, 4.