Development of LGI1-IgG Autoimmune Encephalitis Outcome Rating Score Using the Rasch Analysis
Xiaoyang Li1, Reza Seyedsadjadi2, Pranjal Gupta1, Naveen Paramasivan1, Eoin Flanagan1, Jeffrey Britton1, Anastasia Zekeridou1, Alfonso Lopez3, Gregory Day3, Cristina Valencia Sanchez4, Andrew McKeon1, Sean Pittock1, Divyanshu Dubey1
1Mayo Clinic, Rochester, 2Massachusetts General Hospital, 3Mayo Clinic, Jacksonville, 4Mayo Clinic, Scottsdale
Objective:
To develop a disease-specific outcome rating scale for patients with LGI1-IgG autoimmune encephalitis and to compare its performance with existing outcome measures.
Background:
Current outcome measures lack sensitivity in tracking clinical changes in LGI1-IgG autoimmune encephalitis, highlighting the need for improved tools to assess disease severity and treatment response.
Design/Methods:
The LGI1-IgG autoimmune encephalitis Outcome Rating (LOR) score was developed through expert consensus and literature review. It was initially applied to a score development cohort of 81 patients, followed by Rasch analysis to evaluate item-person targeting, reliability, and dimensionality. Based on this analysis, adjustments were made to improve psychometric performance. The revised scale was re-applied to the score development cohort and then validated in a separate cohort of 54 patients.
Results:
The final LOR score consisted of six items: seizure type, seizure frequency, gait, memory, orientation, and psychiatric disturbance, with scores ranging from 0 to 19. The scale demonstrated excellent inter-rater and intra-rater reliability (κ >0.85). The reliability (0.63) and separation (1.34) were within an acceptable range, indicating very small random errors. The scoring within each item proportionally reflects the item difficulty. The LOR score was unidimensional and able to capture patients across varying levels of severity, without major floor or ceiling effects. Compared to the CASE score, the LOR score can better differentiate among mild, moderate, and severe cases and detect subtle clinical changes, especially in the early or late stages of the disease.
Conclusions:
The LOR score is a reliable, sensitive, and unidimensional outcome measure for LGI1 IgG autoimmune encephalitis. It offers an improved tool for clinical practice and potential use in future clinical trials to track disease severity and therapeutic response.
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