Nearly 25K Were Living With ALS in 2017, US Registry Estimates

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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The estimated 2017 U.S. prevalence of individuals with amyotrophic lateral sclerosis (ALS) was 24,821, or 7.7 per 100,000 people, according to a recent report from the National ALS Registry.

While a statistical model was used to account for potentially missing data, the research team emphasized that this number is still an estimate, noting, “it is challenging to ensure that all newly diagnosed and prevalent ALS cases in the United States are captured.”

The study, “Prevalence of amyotrophic lateral sclerosis in the United States using established and novel methodologies, 2017,” was published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration.

In 2008, the U.S. Congress passed the ALS Registry Act, which authorized the creation of the National ALS Registry  by the U.S. Centers for Disease Control and Prevention’s (CDC) Agency for Toxic Substances and Disease Registry (ATSDR). This registry keeps track of known ALS cases in the U.S. and their demographics.

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Led by scientists at the CDC, the research team now reported the estimated prevalence of ALS in the U.S. in 2017, which is the most recent prevalence report from the registry.

The registry employs a two-pronged approach to identify ALS cases. First, a large computer algorithm combs data from administrative databases including Medicare, the Veterans Health Administration, and Veterans Benefits Administration to identify definite cases. Second, ALS patients are able to self-enroll in the registry via a secure web portal.

For 2017, the registry found 17,800 people with definite ALS, amounting to a U.S. prevalence of 5.5 per 100,000 people. The lowest ALS prevalence was observed in people ages 18 to 39 (0.6 cases per 100,000), and the highest occurrence was among those ages 70–79 (19.5 per 100,000).

As with previous analyses, ALS was observed more frequently in males (7 per 100,000) than females (4.1 per 100,000). Rates of ALS in white Americans (5.5 per 100,000) was almost twice those observed in Black Americans (2.8 per 100,000).

While the registry captures many ALS cases, it cannot account for all people with ALS, since some people may not be included in government databases or did not self-enroll. The research team used a statistical approach called “capture-recapture” to estimate the percentage of missing cases, which was determined to be 44%.

This would mean that the 17,800 individuals in the registry comprised 56% of actual ALS cases in the U.S., and that 14,043 cases were missing. In other words, according to the model, the maximum prevalence of ALS in the U.S. for 2017 could be up to 31,843 people.

Generally, trends observed with age, sex and race remained the same in the adjusted analysis.

The adjusted prevalence rates showed that those aged 18–39 still had the lowest prevalence (1.2 per 100,000) and those aged 70 -79 had the highest (29.8 per 100,000).

Males still had a higher ALS prevalence (9.8 per 100,000) than females (5.9 per 100,000). Similarly, ALS occurred more in the white population (6.9 per 100,000) than the Black population (3.6 per 100,000).

“Findings from both methods demonstrate that ALS continues to impact Whites, especially males, more so than any other group,” the researchers wrote.

“While every effort has been made to determine case counts of ALS in the US, it is not possible to ascertain all cases when data are fragmented, and disease notification is not required nationally,” the researchers wrote.

For example, many patients may be using private insurance providers at the time of their diagnosis. These patients probably account for many of the estimated missing cases in the capture-recapture method, they noted.

Nonetheless, the data in the report might represent the range of likely ALS cases in the U.S. The 17,800 definite cases captured by the registry would be the minimum number of possible cases, whereas the estimated value of 31,843 could be considered an upper limit, the researchers said.

The mean between the two, at 24,821 cases, or or 7.7 per 100,000 individuals, is likely a good estimate of the true prevalence, they added.

If reported registry data from previous years were adjusted in the same way the 2017 data was, the ALS prevalence per 100,000 people would be 7 in 2014, 7.2 in 2015, and 7.1 in 2016.

The team noted that this increased prevalence observed in 2017 is not likely to be a true increase in ALS cases, but rather a better and more accurate estimate, noting that “additional years of data are needed to determine trends.”

In future years, the registry will seek to include new data sources, such as information from ALS-patient organizations or private insurance databases with patient consent.

“CDC/ATSDR is committed to monitoring trends of ALS prevalence in the United States and advancing ALS research,” the team concluded.