Increased morbidity and mortality in acute human organophosphate-poisoned patients treated by oximes: a meta-analysis of clinical trials.

Organophosphates are one of the most common causes of poisoning, especially in the Third world, with high morbidity and mortality. The treatment of this type of poisoning involves the use of atropine and oximes. Atropine has been used successfully in large doses to counteract the muscarinic effects of organophosphate poisoning, but the efficacy of oximes in the management of this poisoning remains under question. In this study, we undertook a meta-analysis by reviewing all clinical trials to evaluate the efficacy of oximes in the management of organophosphate poisoning. The databases of PUBMED, EMBASE, Cochrane, SCOPUS, and the search engine of Google were searched for all clinical trials on the use of oximes in organophosphate poisoning. The inclusion criteria were death, development of intermediate syndrome, and need for ventilation. Six clinical trials met the inclusion criteria and were included in the metaanalysis. The chi2 tests for heterogeneity (P = 0.25, 0.16, and 0.33, respectively) indicated that the included studies were not significantly heterogeneous and could be combined. A significant relative risk (P = 0.0017) for death among oxime-exposed was 2.17 (95% CI of 1.34-3.51). The 'need for ventilation' in patients who received oxime was higher (P = 0.03) than those who did not receive oxime with a relative risk of 1.53 (1.16-2.02). The incidence of 'intermediate syndrome' for oxime-exposed patients was significantly higher (P = 0.01) than oxime non-exposed patients with a relative risk of 1.57 (95% CI 1.11-2.11). It can be concluded that oximes are not effective in the management of organophosphate-poisoned patients and, surprisingly, they can be dangerous and worsen the patient's clinical situation.