Evaluating the Diagnostic Value of atropine challenge test in assessing patients with Suspected Organophosphate Poisoning Referring to the Hospital Emergency Department

Organophosphate poisoning is among the most common types of poisoning. Rapid diagnosis and initiation of treatment for this poisoning can significantly affect the treatment outcome. The definitive method of diagnosis for this poisoning is measuring blood choline esterase level, which requires a lot of time and is not appropriate for timely treatment in the emergency department. Atropine challenge test is one of the tests commonly used in emergency settings. The aim of this study was to assess the effectiveness of this test in diagnosis of organophosphate poisoning.

This cross-sectional study was performed by evaluating the results of atropine challenge test recorded in the medical profiles of 91 patients with suspected organophosphate poisoning, presenting to the poisoning center of Loghmane Hakim Hospital throughout 2018, and comparing the results with those of their serum acetylcholinesterase levels as the gold standard.

Out of the 420 patients presenting to the hospital with organophosphate poisoning throughout 2018, there were 108 patients who had symptoms, for 91 of which atropine challenge test was performed. After comparing the results with the results of the standard test, the sensitivity of atropine challenge test was calculated to be 68.8\% and its specificity was 82.6\%. The test had 26.9\% false negative, 20.5\% false positive, positive predictive value of 79.48, negative predictive value of 73.07\%, positive likelihood ratio of 3.95, and negative likelihood ratio of 0.37.

Considering the high prevalence of poisoning with organophosphates in developing countries and the significant effect of rapid diagnosis and treatment of patients on improving their treatment outcome, atropine challenge test can be used as an acceptable test for screening and confirming the diagnosis of poisoning in suspected cases in the emergency setting.