Rural living may widen gap between early ALS symptoms, diagnosis

For rural patients, getting diagnosed more dependent on major symptoms

Andrea Lobo, PhD avatar

by Andrea Lobo, PhD |

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Having possible symptoms of amyotrophic lateral sclerosis (ALS) increases the chances of getting an ALS diagnosis by nearly five times, but getting diagnosed is more likely for people in urban areas, who have greater access to specialized care, a U.S. study shows.

People in rural areas are diagnosed at a later age and their diagnosis is more dependent on major ALS-specific symptoms, such as muscle weakness and difficulty swallowing or speaking.

The findings underscore the “need to accelerate the detection-to-diagnosis timeline of ALS,” particularly for underserved populations in rural areas, the researchers wrote in “Rurality modifies the association between symptoms and the diagnosis of amyotrophic lateral sclerosis,” which was published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration.

ALS is caused by progressive damage to motor neurons, which are specialized nerve cells responsible for voluntary muscle movements. Evidence suggests early symptoms may appear about a year before the disease is formally diagnosed. These symptoms are often ambiguous, however, and can be missed in many patients, especially where access to specialists is limited, such as rural areas.

Here, researchers in the U.S. studied the association between possible ALS symptoms and a later diagnosis, and whether that association changed in urban or rural areas.

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Chances of an ALS diagnosis

The scientists used national insurance claims-based data from 2001 to 2021. The study included 19,226 people newly diagnosed with ALS and a control group of 96,126 people without ALS, who were matched to patients in age, sex, and enrollment period.

The researchers considered eight groups of symptoms as possible signs of ALS: speech problems, swallowing problems, muscle strength, gait problems, involuntary muscle movements, pain, falls, and other symptoms. The symptoms were assessed up to a year before the diagnosis.

A greater proportion of those who were later diagnosed with ALS had at least one possible symptom than those who weren’t diagnosed with the disease (83.7% vs. 50.7%). There were also more patients than controls with four or more symptoms before a diagnosis (25.5% vs. 4.7%).

Having at least one possible ALS symptom increased the chance of a diagnosis by 4.92 compared with not having a symptom, statistical analyses indicated. Also, as the number of symptoms increased, the likelihood of a diagnosis increased — being 33.2 times more likely in people with five symptoms.

The participants who lived at any time in an urban area were 44% more likely to be diagnosed with ALS than those in rural areas.

Both having possible ALS symptoms and living in an urban area increased the chances of an ALS diagnosis. The difference between urban and rural areas was smaller among those who showed symptoms, however. This means “having a possible ALS symptom reduces the urban bias of ALS,” said the researchers, who then showed the association between possible ALS symptoms and a diagnosis was evident at least a year before a diagnosis, suggesting “ALS symptoms may start appearing and being noted clinically at least [one] year before the diagnosis of ALS is made.”

Next, as differences in ALS incidence in urban and rural areas hadn’t been reported, the researchers hypothesized that the differences in diagnosis resulted from greater access to care in urban areas. This would probably result in being diagnosed at an earlier age in these regions, which analyses confirmed.

“If the age-dependent incidence of ALS is similar between urban and rural places, this finding would suggest people with ALS are being diagnosed earlier in their disease course and with presumably lower symptom burden when they live in urban areas,” wrote the researchers, who noted that “rural populations, which are disproportionately elderly and face limited access to specialist care, are more dependent on major symptoms to arrive at a diagnosis.”