Early biomarker prognostic signals for 30-day mortality in acute poisoning: exploratory analysis of a complete-case...

Reliable early prognostic tools for acute poisoning remain limited. This study examined whether four first-measured routine biomarkers - glucose, lactate, bicarbonate, and white blood cell count (WBC) - carry prognostic signal for 30-day mortality in emergency department (ED) patients with acute poisoning, using a pre-processed, de-identified electronic health records dataset derived from MIMIC-IV (Medical Information Mart for Intensive Care, version 3.1; a publicly available critical care database from Beth Israel Deaconess Medical Center, Boston, USA, hosted on PhysioNet; n=12,039 ED visits; 59 deaths; 30-day mortality 0.49%). Due to extreme non-random missingness across all four biomarkers (lactate 95.2%; bicarbonate/glucose/WBC 88-89%), multivariable modelling was restricted to a complete-case subgroup (n=503; deaths=19). This subgroup was markedly non-representative: intensive care unit (ICU) admission rate 66.4% versus 2.1% in excluded visits (standardised mean difference [SMD]=1.844), reflecting selective laboratory ordering in clinically severe patients. In univariable analyses across available cases, all four biomarkers were significantly associated with 30-day mortality. Within the complete-case subgroup, glucose alone demonstrated good discrimination (area under the receiver operating characteristic curve [AUROC]=0.812; 95% confidence interval [CI] 0.721-0.885), and glucose and WBC were independently associated with mortality in multivariable analysis (adjusted odds ratios [aOR] 1.05 and 1.13, respectively). The calibration slope of 0.646 for the primary four-biomarker model indicated systematic overestimation of absolute risk. These findings are strictly exploratory. Critical limitations - extreme non-random missingness, ICU-enriched complete-case subgroup, absent age and vital signs, low event count (n=19), and absence of external validation - preclude clinical application. This work defines data and design requirements for a future adequately powered prospective prognostic study in acute poisoning.