Combining Axon and IRIS Registry Data for Visual Acuity Comparison

This technical report outlines a study aimed at comparing real-world visual acuity (VA) outcomes between individuals with Multiple Sclerosis (MS) and Neuromyelitis Optica (NMO) by integrating data from two registries: the Axon Registry and the IRIS Registry. The study emphasizes the importance of vision as a critical outcome in both conditions, noting that visual outcomes are generally worse in NMO compared to MS. The report details the methodology of combining de-identified electronic health record data from these registries, which include millions of unique patients, to enhance the understanding of visual outcomes. It discusses potential biases in previous studies and highlights the advantages of using a combined registry approach to mitigate selection bias. The findings suggest that this method can identify a greater number of patients with VA data than using a single registry, thereby broadening the scope of real-world outcomes studies. Limitations of the study, including demographic data issues and the reliance on ICD codes for diagnosis, are also addressed.