Acute Kidney Injury, Creatinine-Derived eGFR Trajectories, and Admission Severity Markers in Acute Methanol Poisoning: A Single-Center Retrospective Cohort Study

Background and Objectives: Acute methanol intoxication is characterized by metabolic acidosis, neurotoxicity, acute kidney injury (AKI), and mortality. Although systemic inflammatory indices have been proposed as prognostic markers, their independent prognostic role beyond established severity markers remains uncertain. We evaluated whether admission inflammatory indices were independently associated with in-hospital mortality and AKI at admission and derived an exploratory Methanol Acute Injury Score (MAIS-4). Materials and Methods: This retrospective cohort included 86 patients with probable acute methanol poisoning. Admission inflammatory indices and exploratory creatinine-derived eGFR trajectories were evaluated. Multivariable logistic regression assessed adjusted associations with creatinine-defined AKI according to KDIGO criteria at admission and in-hospital mortality. MAIS-4 was evaluated by ROC analysis and bootstrap optimism correction of the fixed-category Firth model. Results: The cohort was predominantly male (93.0%); median age was 54.5 years. In-hospital mortality occurred in 47 patients (54.7%), and AKI was present at admission in 60 patients (69.8%). In unadjusted analyses, NLR, PLR, SII and SIRI were lower in non-survivors, and PLR was lower in patients with admission AKI. No independent association was detected for any index after adjustment. In adjusted analyses, lower Glascow Coma Scale scores were associated with mortality and lower arterial pH with AKI at admission. Among survivors, 30.8% had a final creatinine-derived eGFR below the documented baseline. MAIS-4, incorporating Glasgow Coma Scale score, arterial pH, serum albumin, and admission AKI, showed an apparent AUC of 0.938 for mortality (optimism-corrected AUC of the fixed-category Firth model, 0.919) with 76.6% sensitivity and 94.9% specificity at ≥5 points. Conclusions: No independent association of admission inflammatory indices with in-hospital mortality or AKI at admission was detected after adjustment for core metabolic and neurological severity markers. MAIS-4 is an exploratory derivation score that requires external validation.