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Survey Identifies New Phenotypic Features for Patients With NMOSD in Latin America

Disease Spotlight | <b>Disease Spotlight: NMOSD</b>

The study is the first to provide data from all Latin American countries, further identifying geographic-resultant limitations of access to technology and therapy for NMOSD.

A recent study initiated by The Latin American Committee for Treatment and Research in MS, or LACTRIMS, evaluated the different ethnic distributions and phenotypic features of neuromyelitis optica spectrum disorder (NMOSD) within Latin America (LATAM). The survey was the first of its kind and the first to include all countries in LATAM, providing data from 2154 patients with NMOSD.

Investigators, led by Victor M. Rivera, MD, FAAN, distinguished emeritus professor, department of neurology, Baylor College of Medicine, included 62 investigators from 21 countries, with patient data categorized into the North-Central (NCC) region (n = 792), which included the Caribbean, or the South America (SA) region (n = 1362). The survey had 25 themes, including type of practice definitions, number of NMOSD cases, ethnicity, clinical phenotypes, local access to anti-aquaporin-4 (AQP4) and anti-myelin oligodendrocyte glycoprotein (MOG) testing, among others. The 2015 NMOSD diagnostic criteria were utilized in 93.9% of cases. 

Of concomitant autoimmune conditions, the most common were lupus erythematosus (6.3%), Sjogren’s syndrome (3.3%), anti-phospholipid syndrome (2.7%), and rheumatoid arthritis (0.6%). A total of 677 patients (31.4%) presented with optic neuritis (ON) without associated transverse myelitis (TM) at diagnosis (P <.001), 686 patients (31.8%) presented with a combination of ON and TM (P = .05), and 573 patients (26.6%) presented with TM without ON (P = .23). 

Approximately 21.5% of cases had area postrema syndrome, and more were found in the SA region (24.6%; P <.001). Brain stem involvement was reported in 8.3% of total patients (n = 180) and more prevalent in the SA region, at a rate of 11.7% (n =159; P <.001). Spinal cord involvement among groups, whether alone or combined with ON, had no significant difference in these cases. 

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The survey also found that anti-AQP4 antibodies were presented for 63.9% of patients, primarily in the NCC region at a rate of 73.8% (n = 585; P <.001), with serologic analysis performed in 95.4% of NMOSD cases in this sample. A total of 50.7% patients were assessed for anti- Myelin oligodendrocyte glycoprotein (MOG) antibodies, with 4.8% proving positive (n = 105). Those with the anti-MOG antibodies were more likely to reside in the SA region (5.9%; P = .002). 

Acute relapses were reported in 81.6% of cases (n = 1758). Therapeutic approaches were evaluated according to survey responses, with respondents reporting that intravenous steroids were used to treat acute relapses in 93.9% of cases, plasma exchange in 62.1% of cases, and intravenous gamma globulin in 40.9% of cases. Investigators reported that 6.06% of cases were escalated in case of suboptimal initial response.

Treatments for long-term management of NMOSD included rituximab infusions (86.3%), oral azathioprine (81.8%), mycophenolate (50.0%), cyclophosphamide (21.0%), and methotrexate (7.9%). Utilization of rituximab and azathioprine, which were noted as the favored treatment routes, was dependent on accessibility or clinical judgement, and no differences were identified between the SA and NCC regions.

“Most Latin American countries remain in the phase of economic development resulting in limitation of access to adequate diagnostic technology and therapy for NMOSD,” Rivera et al wrote, addressing the question of accessibility. “The high cost of some drugs, not just the ones specifically licensed for treatment of the disease by international health agencies, but also the ones frequently utilized off-label, add to challenges of adequate and accessible management of the disease in the region.”

Mestizos were found to be the largest ethnic group disclosed, accounting for 61.4% of patients (n = 1323) across the LATAM area, but was more prevalent in the SA region, compared to the NCC region (P = .005). Additional ethnic groups included Caucasian (18.8%; n = 406), Afro-American (10.5%, n = 226), Native American (4.0%; n = 86), and Asian (0.3%; n = 7). The remaining participants did not report ethnic information (4.9%, n = 109).

Investigators noted that the study was limited due to its cross-sectional design inhibiting its ability to collect longitudinal information, as well as the survey’s online format, which could induce recall bias. To address this potential bias, NMOSD experts were selected as respondents.

“Latin American neurologists should play a determining role in education on NMOSD in LATAM, and in advising and encouraging health officials and institutions on acquisition of updated diagnostic technology, and on the access to approved medications for treatment of the disease,” Rivera et al wrote. “Addressing NMOSD care in the Americas calls for a comprehensive professional and community effort.”

REFERENCE
Rivera VM, Hamuy F, Rivas V. Status of the neuromyelitis optica spectrum disorder in Latin America. Mult Scler Relat Dis. 2021;53:103083. doi:10.1016/j.msard.2021.103083