Relationship between blood alcohol concentration on admission and outcome in dimethoate organophosphorus self-poisoning

AIMS: Many patients acutely poisoned with organophosphorus insecticides have co-ingested alcohol. Although clinical experience suggests that this makes management more difficult, the relationship between plasma concentration of alcohol and insecticide is unknown. We aimed to determine whether acute intoxication results in ingestion of larger quantities of insecticide in dimethoate self-poisoning and a worse clinical outcome. METHODS: We set up a prospective study of acute dimethoate self-poisoning in Sri Lankan district hospitals. An admission plasma sample was analysed to identify the ingested insecticide; in patients with detectable dimethoate, plasma alcohol was measured. RESULTS: Plasma from 37 of 72 (51.4%) dimethoate-poisoned patients had detectable alcohol {median concentration 1.10 g l(−1)[110 mg dl(−1)][interquartile range (IQR) 0.78–1.65]} a median of 3 h post ingestion. The median plasma dimethoate concentration was higher in patients who had ingested alcohol [479 µmol l(−1) (IQR 268–701) vs. 145 µmol l(−1) (IQR 25–337); P < 0.001]. Plasma dimethoate concentration was positively correlated with plasma alcohol (Spearman's ρ= 0.34; P= 0.0032). The median alcohol concentration was higher in the 21 patients who died compared with survivors (0.94 vs. 0.0 g l(−1), P= 0.018). Risk of death was greater amongst individuals who consumed alcohol [odds ratio (OR) 4.3, 95% confidence interval (CI) 1.2, 16.4]; this risk was abolished by controlling for dimethoate concentration (OR 0.3, 95% CI 0.0, 8.8), indicating that deaths were not due to the direct toxic effects of alcohol. CONCLUSIONS: Alcohol co-ingestion is associated with higher plasma concentrations of dimethoate and increased risk of death. Larger studies are required to assess this finding's generalizability, since efforts to reduce deaths from self-poisoning may benefit from concurrent efforts to reduce alcohol consumption.