Prognostic Nutritional Index as a Biomarker of Disease Severity and Long-Term Outcome in Guillain-Barré Syndrome

Guillain-Barré syndrome (GBS) exhibits clinical heterogeneity and variable progression. In low-resource settings, malnutrition and limited treatment worsen prognosis, underscoring the need for a simple prognostic tool. This study evaluated the Prognostic Nutritional Index (PNI) and Nutritional Risk Index (NRI) in relation to GBS severity and long-term outcomes, comparing their predictive value with standard prognostic indicators.

An observational cohort study of 252 GBS patients enrolled between 2019 and 2024 was conducted. PNI and NRI were calculated using serum albumin, lymphocyte count, and body weight. The GBS-disability score (GBS-DS) assessed baseline severity and 26-week outcomes. Statistical analysis included Chi-square tests, Mann-Whitney U tests, Spearman's ρ, and logistic regression to identify predictors. ROC analysis determined optimal PNI cut-offs, confirmed by Kaplan-Meier survival curves.

PNI, unlike NRI, was significantly reduced in severe GBS (GBS-DS > 3) compared to mild/moderate GBS (GBS-DS ≤ 3). PNI correlated with GBS-DS (ρ = -0.62), MRC sum score (ρ = 0.5), hemoglobin (ρ = 0.53), and neutrophil count (ρ = -0.35) (all p < 0.0001). PNI independently predicted disease severity (odds ratio [OR] = 0.91; p = 0.036) and 26-week outcomes (OR = 0.93; p = 0.033). Area under the ROC curve (AUC) was 0.769 for severity and 0.719 for 26-week outcomes. PNI cut-offs of 49.395 and 45.72 predicted severe GBS and long-term poor outcome, respectively. Kaplan Meier analysis confirmed patients with PNI < 45.72 required a longer time to gain independent locomotion (p < 0.0001).

Lower PNI, but not NRI, is associated with greater GBS severity and poor long-term outcomes. PNI independently predicted disease severity and 26-week outcomes, with specific cut-offs identifying patients requiring longer recovery, supporting its prognostic utility.