To summarize the evidence on the association between weight status and the presence of NMOSD.

Neuromyelitis optica spectrum disorder (NMOSD) is an immune-mediated demyelinating disease of the central nervous system. Its inflammatory nature has made it associated with decreased or increased body mass index (BMI). 

A systematic search was conducted in PubMed, Embase, Scopus, Web of Knowledge, and Google Scholar until April 2024. We included observational studies that evaluated the association between BMI levels and NMOSD. Additionally, we analyzed the difference in BMI levels between NMOSD and Multiple Sclerosis (MS) patients. A meta-analysis using a random-effects model to estimate pooled effects was used for each outcome and a narrative synthesis when this was not possible. Healthy controls and MS patients were the comparator, and the outcome was the risk of NMOSD. Additionally, we report adjusted effect size. The Newcastle-Ottawa scale was used to assess the risk of bias.

Sixteen studies were included. A meta-analysis of 8 studies (2423 participants) demonstrated no significant difference in BMI levels between NMOSD patients and healthy controls with high heterogeneity (Mean difference [MD]: -0.78; 95% CI: -2.02 to 0.46; I2 = 93%). Furthermore, a meta-analysis of 7 studies (548 participants) reported no significant difference in BMI levels between NMOSD patients and MS patients with high heterogeneity (MD: 0.04; 95% CI: -1.32 to 1.40; I2 = 93%). Additionally, one study reported that BMI levels were not associated with NMOSD (Adjusted Odds ratio[aOR]: 0.9; 95% CI: 0.6 to 1.6). Finally, all studies reported a low risk of bias.

There was no association between BMI levels and NMOSD. In addition, we did not a difference in BMI levels between NMOSD with healthy controls or MS patients. However, further studies are necessary to confirm these findings.