development of latrodectus envenomation severity score (less); a severity index for widow spider bite: initial step

background: in order to describe the patients and evaluate the effectiveness of treatments for widow spider envenomation, investigators require a reliable assessment tool. in this paper, the development of a clinical index for measuring the widow spider bite severity, latrodectus envenomation severity score (less), is described. methods: according to the valid methods for index development, a delphi group process was applied. a panel of 13 experienced medical toxicologists and physician experts in treatment of black widow spider bites was assembled in december 2013. the participants were asked to score clinical manifestations of latrodectus envenomation based on their importance on the severity and patients' prognosis. hence, an initial draft of the severity index was developed and in the second phase of study, the draft was discussed in a focus group of experts to finally comment on each variable and vote about the final scores. results: the proposed version of less comprises of 34 clinical items categorized in 8 organ systems. the index includes definition of each clinical variable to help users of the index how to ascertain or rule out the clinical finding. the maximum theoretical score according to less is 87. acute renal failure, myocarditis, pulmonary edema and ileus received the highest scores in this index. conclusion: the less is a new assessment tool that is designed to more objectively evaluate the severity and progression of envenomation in victims of widow spider bite. the prognostic-ability, reliability and sensitivity to change of the index should be investigated in future studies.   how to cite this article: monzavi sm, afshari r. development of latrodectus envenomation severity score (less); a severity index for widow spider bite: initial step. asia pac j med toxicol 2014;3:18-22.