Background:Mixed drugs poisoning (MDP) is common in the emergency departments. Because of the limited number of intensive care unit beds, recognition of risk factors to divide the patients into different survival groups is necessary. Poisoning due to ingestion of different medications may have additive or antagonistic effects on different parameters included in the scoring systems; therefore, the aim of the study was to compare applicability of the different scoring systems in outcomes prediction of patients admitted with MDP-induced coma.Methods:This prospective, observational study included 93 patients with MDP-induced coma. Clinical and laboratory data conforming to the Acute Physiology and Chronic Health Evaluation (APACHE II), Modified APACHE II Score (MAS), Mainz Emergency Evaluation Scores (MEES) and Glasgow Coma Scale (GCS) were recorded for all patients on admission (time0) and 24 h later (time24). The outcome was recorded in two categories: Survived with or without complication and non-survived. Discrimination was evaluated using receiver operating characteristic (ROC) curves and area under the ROC curve (AUC).Results:The mortality rate was 9.7%. Mean of each scoring system was statistically significant between time0 and time24 in the survivors. However, it was not significant in non-survivors. Discrimination was excellent for GCS24 (0.90±0.05), APACHE II24 (0.89±0.01), MAS24 (0.86±0.10), and APACHE II0 (0.83±0.11) AUC.Conclusion:The GCS24, APACHE II24, MAS24, and APACHE II0 scoring systems seem to predict the outcome in comatose patients due to MDP more accurately. GCS and MAS may have superiority over the others in being easy to perform and not requiring laboratory data.