#MDA2021 – Occurrence of Bulbar Onset ALS Higher in the Midwest
Amyotrophic lateral sclerosis (ALS) patients living in the Midwest — the U.S. region with the highest ALS frequency — are older and have more bulbar onset disease than the national ALS population, a study suggests.
In addition, military veterans accounted for 20% of ALS cases in the Midwest, a similar proportion to that reported in the National ALS Registry, but nearly three times higher than the mean of the U.S. adult population.
Further studies and registries are needed to better characterize this Midwestern patient population and to clarify a potential link between military service and ALS, the researchers noted.
These findings, based on data from The ALS Association Mid-America Chapter, were presented in a poster “Demographics and Survival of Midwestern Patients with Amyotrophic Lateral Sclerosis,” at the 2021 MDA Virtual Clinical and Scientific Conference, held March 15–18.
While ALS affects people of all races and ethnicities, it is more common among whites, men, adults 60 and older, and those with a family history of the condition.
In the U.S., data from the ALS National Registry shows that ALS occurrence is highest in Midwest, affecting 5.5 per 100,000 people. This higher frequency is thought to be associated with a greater proportion of white people, compared with other regions.
“However, the Midwestern population with ALS has been under-reported,” the researchers wrote.
To fill this knowledge gap, researchers retrospectively analyzed demographic and clinical data from deceased ALS patients from Jan. 1, 2010, to Sept. 1, 2020, who were registered with the ALS Association Mid-America Chapter. The organization has been collecting data from ALS patients living in Kansas, Nebraska, and central/western Missouri for more than 10 years.
The team compared the data with that from the National ALS Registry, and assessed predictors of survival in this Midwestern population. Sponsored by the Centers for Disease Control and Prevention, the National ALS Registry was created to help identify ALS risk factors and disease patterns, as well as potential clinical trial candidates.
The Mid-America Chapter database included 1,447 people with ALS, of whom 62% had symptom onset data available. Nearly 30% of them (404 patients) did not show up at any registered clinics at tertiary centers for 10 years (non-clinic population).
Results showed that their median survival since diagnosis (14 months) was shorter than that reported in previous studies from other U.S. states (19–21 months), but time from symptom onset to death (28 months, nearly three years) was similar to previous reports.
Notably, the ALS patient population in the Midwest was older than that in the National ALS Registry (72% vs. 48% of patients were 60 and older), and had a higher frequency of bulbar onset disease (29% vs. 22%). Bulbar onset ALS first affects muscles involved in speaking, swallowing, and breathing.
Military veterans accounted for 19.8% of all patients, which was comparable to the 24% reported in the National Registry. However, both these figures were higher than the mean of 7% of veterans among the U.S. adult population, highlighting a greater prevalence of military service among ALS patients.
In this Midwestern patient population, being a woman, a veteran, or having bulbar onset disease was associated with older age at diagnosis, while familial ALS was linked to younger age at diagnosis.
Veterans were diagnosed at an older age, compared with non-veterans (mean of 70.8 vs. 64.5 years), but this was likely due to the absence of a younger veteran population in the dataset, the team noted. These older veterans had survival and disease duration similar to non-veterans.
In addition, data showed that bulbar onset disease and diagnosis at 65 years or older were predictors of poorer survival, while the use of non-invasive ventilation was associated with longer survival.
Compared with the clinic population, a greater proportion of patients among the non-clinic population were men, had familial ALS, and used ventilatory support. However, feeding tube and non-invasive ventilation use was less common in this group of patients.
“There is no clear explanation why Midwestern population with ALS were older at diagnosis with more bulbar onset disease compared to the National Registry,” the researchers wrote.
However, they hypothesized this may be associated with the observed shorter survival in this population, compared with other studies, which may include a mainly clinic population at tertiary centers that may miss patients with fast disease progression.
Given that this Midwestern patient population contained patients not showing up at registered clinics, The ALS Association “could potentially serve as the connection to the non-clinic population in the future, especially when a genetic treatment becomes available for familial diseases,” the researchers added.
Further studies are needed to better characterize ALS patients in the Midwest, clarify the disease course of younger veterans — who were absent in this population — and investigate the cause of higher incidence of military service among ALS patients compared to the general population, they concluded.