The U.S. prevalence of amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease, is about 4 cases per 100,000 Americans, according to the Centers for Disease Control and Prevention.
Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disorder that is usually fatal within 2-5 years of diagnosis. A hereditary form of the disease accounts for between 10% and 15% of cases. In the rest, the cause or causes are unknown, although chemical and infectious exposures are among the suspected triggers.
The new prevalence figures, which the CDC published in its Morbidity and Mortality Weekly Report issued July 25 (MMWR 2014;63[SS07]:1-14), represent the first national prevalence findings for ALS in the United States, and derive from surveillance begun in 2009 by the federal Agency for Toxic Substances and Disease Registry in Atlanta, where Dr. Paul Mehta led the investigation.
Dr. Mehta and his colleagues identified cases from Medicare, Medicaid, Veterans Heath Administration, and Veterans Benefits Administration databases, as well a secure public website through which ALS patients could self-report to the CDC by answering a series of screening questions.
Between October 2010 and the end of 2011, the registry identified 12,187 people 18 years and older with ALS, for a prevalence of 3.9 cases of ALS per 100,000 – findings that are consistent, the researchers said, with those from long-running European ALS registries.
As in other studies, men had a higher prevalence of ALS than did women (4.8 per 100,000 vs. 3.0 per 100,000). "Factors such as occupational history and environmental exposures might be associated with this finding," the researchers wrote in their analysis.
The prevalence of ALS among whites was more than double that of blacks (4.2 per vs. 2.0). "The reason for this difference in prevalence by race is unknown and needs to be investigated further," Dr. Mehta and his associates wrote. However, they noted, the race findings were also consistent with other studies.
The age group 70-79 was associated with the highest prevalence rate, at 17.0 per 100,000, followed by 60-69 at about 12.
Dr. Mehta and his colleagues acknowledged that their study had several limitations, including the fact that the ALS registry was relatively new; that ALS is not a notifiable disease in most states, making it difficult to capture all cases; that data errors or file duplication could have occurred; and that it was not possible to calculate ALS incidence, only prevalence, because most cases in the registry did not have a diagnosis date.
No conflicts of interest were mentioned in the report.