Disability assessment tool specific to NMOSD is needed: Study
Findings show EDSS failed to capture certain demographic, clinical factors
People with neuromyelitis optica spectrum disorder (NMOSD) who test positive for NMOSD-driving self-reactive antibodies against the AQP4 protein and Black patients are significantly more likely to have worse disability related to vision.
These are the findings of a North American study that analyzed patient data with NMOSD-specific disability scales related to mobility, vision, and self-care. The associations between demographic and clinical factors and disability weren’t detected by the Expanded Disability Status Scale (EDSS), however, which was developed for multiple sclerosis, a related disease.
“These findings provide substantive evidence supporting the need for development of novel instruments for improved detection of disability and resilience in patients with NMOSD,” the researchers wrote. The study, “Assessment of disability and disease burden in neuromyelitis optica spectrum disorders in the CIRCLES Cohort,” was published in Scientific Reports.
NMOSD is a rare progressive autoimmune disease that causes inflammation in the optic nerve, which relays signals between the brain and the eyes, and the spinal cord. Most cases are associated with the production of self-reactive antibodies against the AQP4 protein.
People with NMOSD have a range of symptoms including eye pain, vision problems, pain, muscle weakness, and cognitive problems. Most have flare-ups, or relapses, between periods of recovery (remission). Symptoms tend to worsen with each relapse, with damage accumulating, which leads to significant disability in most patients.
“Real-world assessment of disability patterns unique to NMOSD would be an essential component of comprehensive care” to “enable prognostic capabilities for preventive intervention and promote enhanced patient resilience and quality of life,” the researchers wrote. “However, such assessments are limited due to the fact that disability evaluation relies on measures and instruments that were not designed or optimized for NMOSD.”
The EDSS, which is often used in NMSOD diagnosis and monitoring, and in NMOSD clinical trials, “may be suboptimal for NMOSD,” the researchers wrote. The scale focuses on mobility and contains few measurements of disability related to vision, bowel/bladder dysfunction, and self-care, and little to no assessments of pain, cognitive impairment, or mental health. This means “EDSS has key limitations regarding assessment of disabilities that are commonly seen in patients with NMOSD,” the researchers wrote.
NMOSD-specific tool vs. EDSS
Here, researchers assessed the need for an NMOSD-specific disability tool by analyzing data from 505 NMOSD patients with a NMOSD-specific composite scale versus the EDSS. The NMOSD-specific modular disability scale was developed to assess real-world disability in a way the EDSS is unable to. It contains three disability domains — mobility, vision, and self-care — each assessed in a 7-point scale.
All the patients had participated in CIRCLES, a real-world study that collected data and samples from patients and control participants from 15 North American academic medical centers from 2013 and 2020. Most patients were women (86.3%), white (55%), and tested positive for anti-AQP4 self-reactive antibodies (82.6%). They’d had their first NMOSD episode at a median age of 38.7 and 29.3% had a relapse during the study.
Having a relapse during the study was associated with worsening disability in the individual NMOSD-specific mobility, vision, and self-care scales, as well as in the composite measure of all three scales. Those who’d had the disease for less than a year were significantly less likely to have worsening vision-related disability over time, compared with those with longer disease duration.
Demographic, clinical features
A subgroup of 198 patients was used to assess potential links between demographic and clinical features, and changes in disability domains, as these patients had more comprehensive data, including pain and cognitive function assessed with standard measures.
Being Black, having anti-AQP4 self-reactive antibodies, and being in the study for less than two years were significantly associated with a higher likelihood of more severe vision-related disability. These associations weren’t detected with the EDSS, however.
Older age was significantly associated with worse EDSS-based disability, but “age was not associated with disability measured using any of the NMOSD-specific assessments,” the researchers wrote.
Women with NMOSD had significantly more severe limitations on daily activity and quality of life due to pain than men. Also, the patients with disease onset related to inflammation in the spinal cord, optic nerve, and other brain areas had the most severe pain-related limitations on activity and quality of life.
Black patients had worse pain and more cognitive problems than white and Asian patients. Hispanic patients also reported more cognitive problems than white patients.
These findings “support the hypothesis that outcomes in NMOSD are linked to race or ethnicity,” wrote the researchers wrote, who noted they also “offered insights into higher-resolution and domain-specific disability outcomes in NMOSD that were undetected by EDSS.”
“The current study provides quantitative evidence supporting the need for an NMOSD-specific disability assessment instrument,” they wrote.
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