Other Non-immune Diseases Raise Risk of Vision Loss in NMOSD: Study

Screening for comorbidities may help predict disease progression

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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People with neuromyelitis optica spectrum disorder (NMOSD) who are diagnosed with at least one non-immune system comorbidity, or simultaneous disease, are at a higher risk of vision loss and paralysis than those without such conditions, a study found.

NMOSD patients with these comorbidities also were significantly more likely to be older and to not respond as well to immunotherapy — treatments often prescribed for managing the progressive disease.

These findings suggest that screening people with NMOSD for non-immune system comorbidities may help predict disease progression, according to researchers.

“When the symptoms of NMOSD overlap with those of comorbidities, they are easily masked, thereby exacerbating disability progression,” the team wrote.

The study, “Non-immune system comorbidity in neuromyelitis optica spectrum disorders,” was published in the Journal of Clinical Neuroscience.

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Older patients at high risk

NMOSD occurs when the immune system wrongly produces antibodies against proteins in neuron-supporting cells, causing inflammation in the optic (eye) nerve and spinal cord.

This can lead to symptoms such as poor vision, changes in sensation, muscle pain and weakness, and loss of coordination, which may get worse and result in paralysis.

People with NMOSD often have other health conditions, from autoimmune diseases such as lupus and Sjögren’s syndrome, to non-autoimmune conditions like high blood pressure, diabetes, migraine, cancer, and psychiatric disorders.

Previous studies showed that NMOSD patients with other autoimmune diseases have a higher relapse rate and poorer prognosis than those without such conditions. However, there is limited evidence on the extent to which non-immune system comorbidities may influence the disease’s course.

To learn more, a team of researchers in China retrospectively analyzed data from 138 adults with NMOSD and at least one non-immune comorbidity and 404 NMOSD adult patients without comorbidities, who served as controls. All were admitted to the West China Hospital, in Chengdu, between January 2009 and December 2021.

Among the comorbidity group, most patients (73%) had one simultaneous non-immune system condition. A total of 28 individuals (20%) had two non-immune cormorbidities, while eight (6%) had three, and two (1%) had four. The most common comorbidity was high blood pressure (31.9%), followed by diabetes (21%) and hyperlipidemia (15.9%). Hyperlipidemia is an excess levels of fatty molecules in the blood.

Compared with patients without comorbidities, those with co-existing non-immune conditions were significantly older at symptom onset (45 vs. 38 years) and significantly more likely to experience relapses after receiving immunotherapy (68.5% vs. 54.5%).

Moreover, a significantly greater proportion of patients in the comorbidity group showed damage in multiple areas of the brain and spinal cord as their first sign of disease, compared with those in the non-comorbidity group (30.4% vs. 18.3%).

Patients with at least one non-immune comorbidity also were significantly more likely to experience severe vision attacks (28.3% vs. 15.8%) and severe motor attacks (30.4% vs. 11.9%).

“We found that the number of patients who developed blindness in one or both eyes and limb paralysis in the course of the disease was significantly higher in the comorbidity group than in the non-comorbidity group,” the team wrote.

No significant group differences were detected in terms of disease course, number of relapses, mortality, and treatment.

There also were not any differences of significance in first scores on the Expanded Disability Status Scale (EDSS) or in the rate of patients positive for antibodies against aquaporin-4 (AQP4). EDSS is a 10-point scale measuring a patient’s level of disease-related disability, with higher scores indicating worse disability. AQP4 is the most common target of NMOSD-related antibodies.

The number of patients who developed blindness in one or both eyes and limb paralysis in the course of the disease was significantly higher in the comorbidity group than in the non-comorbidity group

These findings highlighted that NMOSD patients with non-immune comorbidities “tended to be older, less responsive to treatment, and at a higher risk of vision loss and paralysis,” the researchers wrote.

Further analyses showed that, after adjusting for potential influencing factors, older age at symptom onset, longer disease duration, diabetes, and the presence of anti-AQP4 antibodies significantly increased the risk of scoring six points or more in the EDSS. Such high scores mean that people require an aid such as a cane or crutches to walk.

In turn, receiving treatment cut the risk of scoring this high in the EDSS by about half.

“In this retrospective study, we found that patients with NMOSD in the comorbidity group were older at onset, the prevalence of comorbidities increased with age, and more elderly patients were likely to have age-related comorbidities,” the researchers wrote.

“Comorbidities appear to be an important factor influencing disability in patients with NMOSD,” the team wrote, adding that “comorbidity screening should be emphasized as part of patient care.”