Changing nomogram risk zone classification with serial testing after acute acetaminophen overdose: a retrospective database analysis

AbstractContext: The Rumack–Matthew nomogram stratifies patients into discrete risk zones following acetaminophen (APAP) overdose. Treatment decisions have traditionally been based on the initial risk zone. “Line-crossing” between zones occurs and is poorly understood. The study objective was to characterize line-crossing behavior in acute APAP overdose patients, especially moving from below to above the nomogram treatment threshold.Methods and materials: The study was a secondary analysis of the Canadian Acetaminophen Overdose Study (CAOS) database, a large medical record review of patients hospitalized in eight large Canadian cities (1980–2005) following APAP poisoning. Population consisted of acute APAP overdose patients with at least two serum concentrations performed during hospitalization. Using ordinal logistic regression, we studied the effects of patient demographics, ingestion size/timing, APAP concentrations, time to N-acetylcysteine (NAC), and co-ingestants on a three-level dependent variable:...