A Systematic Review on the Role of Neutrophil to Lymphocyte Ratio as a Prognostic Marker in Autoimmune Encephalitis

Background One potential autoimmune encephalitis (AE) prognostic marker is the neutrophil to lymphocyte ratio (NLR). NLR can predict outcomes in other diseases, including sepsis, and its prognostic utility has been reported in AE. Here we perform a systematic review on the prognostic role of NLR in AE in children and adults. Methods Two independent searches were conducted in PubMed and EBSCO and included articles from January 1, 2000, until April 24, 2024. Studies were included if the article was in English, included NLR in AE, and used the JBI evidence checklist for case series. Exclusion criteria included case reports. Summary statistics were performed. Results Sixteen studies were included (2 pediatric and 14 adult). Five studies (1 pediatric, 4 adult) were exclusively in anti– N -methyl- d -aspartate (anti-NMDA) receptor encephalitis (NMDARE). Eight investigated definite (antibody-positive) AE and three included probable (antibody-negative or antibody status unknown) AE (one pediatric, two adult). The NLR cutoff ranged from 3.45-10.19. In children, NLR was associated with intubation and rehabilitation length of stay in NMDARE and disease severity in definite and probable AE. In confirmed adult AE, high NLR was associated with disease severity (2), intensive care unit admission (1), poor neurologic outcomes (3) and first-line treatment failure (2). In the four adult NMDARE studies, high NLR was associated with first-line treatment failure (1), disease severity (2), and poor neurologic outcomes in patients requiring mechanical ventilation (1). Conclusions NLR may be a prognostic marker for AE in children and adults.