Risk Factors for Permanent NMOSD Disability ID’d in Mexican Study

Permanent disability was seen where patients were older and had a longer disease duration

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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Older age, diagnostic delays, and a greater disability at diagnosis were associated with a higher risk of developing permanent disability for people with neuromyelitis optica spectrum disorder (NMOSD) at a center in Mexico.

“This information is required to design healthcare strategies to recognize and treat patients with NMOSD early and aggressively to decrease the rates of [permanent disability] and their effect on both the patients and society,” the researchers wrote.

The study, “Risk factors associated with permanent disability in neuromyelitis optica spectrum disorders,” was published in Multiple Sclerosis and Related Disorders. 

NMOSD is a progressive autoimmune disorder marked by episodes of inflammation that affect the spinal cord and optic nerve, the nerve that sends and receives signals from the eye.

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Most patients have disease flare-ups, or relapses, with periods of remission in between. Each relapse is usually accompanied by progressively worsening neurological impairment and disability, with some patients ultimately reaching a state of permanent motor or visual disability.

The researchers sought to identify risk factors for permanent disability resulting from NMOSD among patients in Mexico. They analyzed 67 NMOSD patients evaluated at a clinic in Guadalajara, Mexico.

Of them, 34 had an initial disease presentation of optic neuritis, or inflammation of the optic nerve, and 24 had myelitis, or inflammation of the spinal cord. Nine presented with area postrema syndrome, a condition marked by damage to a brain region involved in unconscious bodily functions, leading to nausea, vomiting, or hiccuping.

Of 48 patients who were tested, 38 were positive for antibodies against aquaporin-4, the most common NMOSD-causing antibody. At their diagnosis, 38 were prescribed azathioprine and 29 rituximab to induce disease remission.

About half of the patients (34 people) developed permanent disability, defined as being confined to bed or a wheelchair and/or blindness. Blindness occurred in 15 patients, 13 people had permanent motor disability, and six were restricted to a wheelchair.

This rate of disability was higher than that observed in previous studies, researchers noted, which could be due to differences in race, interval between symptom onset and diagnosis, and treatment delays.

Patients who developed permanent disability were older, had a longer disease duration, and a longer interval between symptom onset and treatment compared with those who were not permanently disabled.

Disabled patients also had a higher score on the expanded disability status scale (EDSS) at their first appointment with a neurologist, reflecting a greater degree of disability.

These participants also had more relapses, were more frequently hospitalized than those without permanent disability, and were less likely to use corticosteroids at the time of their first clinic visit.

Being at least 50 at NMOSD onset was deemed a significant risk factor for permanent disability, yielding an almost fivefold higher risk relative to those under 50, according to a final analysis adjusted for the potential influence of the time from disease onset to treatment.

Similarly, a delayed diagnosis was linked to an increased risk of permanent disability. Patients who had a diagnostic delay of at least a year from the time of disease onset had about a five times greater risk of permanent disability.

An EDSS score at the first appointment of at least 4 (reflecting significant disability, albeit self-sufficiency and ability to walk without aid or rest for 500 meters), was also a significant risk factor, raising the risk by 3.4 times.

All the patients in the current study were seen at at a single tertiary care center, the researchers noted. Since patients at these centers usually have a more aggressive disease course, “future studies including patients from secondary-care hospitals, university hospitals, and private practices are required to include a wider spectrum of the disease,” they wrote.