Nomograms applicability in clinical toxicology – enhancing precision in clinical decision-making: a systematic review

Nomograms represent powerful predictive tools that could be easily applied to guide managing acutely intoxicated patients. Thus, several nomograms were developed and validated in the last few decades to predict various outcomes following acute poisoning. However, the adopted nomograms remain sporadic efforts of researchers that limited their usefulness in clinical settings. We aimed to bridge the gap between theoretical formulation and hands-on application of the developed nomograms to benefit acutely poisoned patients. In this context, this systematic review was conducted to be a reference guide for implementing these nomograms in clinical toxicology practice. This review included 27 studies that were published over 60 years. A total of 60,883 patients ranging between 2 and 91 years were enrolled. These studies elaborated 38 nomograms; 13 nomograms addressed acute poisoning in general, and 25 nomograms were specially designed for six poisons/categories, including pesticides (n = 9), psychotropic drugs (n = 5), alcohol (n = 4), analgesics, and anti-inflammatory medications (n = 3), carbon monoxide (n = 2), and digoxin (n = 2). Despite the first nomogram was published in 1960, 81.5% of nomograms emerged after 2016, with a significant increase in the trend of published nomograms (p < .001). The Glasgow Coma Scale, patient age, poison concentration, bicarbonate level, and blood pressure were the most frequently used predictors. The nomograms were designed to predict eight outcomes, including mortality (n = 14, 36.8%), need for intensive care unit (ICU) admission (n = 9, 23.7%), complications of poisoning (n = 6, 15.8%), optimization of therapy (n = 4, 10.5%), and poisoning severity (n = 2, 5.3%). Also, the need for mechanical ventilation (MV), diagnosis of poisoning, and suicidal poisoning were predicted by one nomogram for each of them. The developed nomograms' performances were tested using receiver operating characteristic analysis and the area under a curve of 26 derived nomograms ranged between 0.839 and 0.999. External validation was conducted on 16 nomograms only; 15 nomograms were validated using validation cohorts within the same studies that developed the nomograms. However, only one nomogram was subjected to external validation by other studies. The externally validated nomograms consist of 10 nomograms for managing particular poisoning and, six nomograms for un-specified poisoning. The poison-specific nomograms were concerned with acute poisoning with pesticides (n = 4), methanol (n = 2), opioid (n = 1), clozapine (n = 1), carbon monoxide (n = 1), and digoxin (n = 1). Regarding six validated nomograms in a general poisoning approach, two nomograms predicted mortality. Nevertheless, four separate nomograms were concerned with the prediction of poisoning complications, the need for ICU admission, the need for MV, and suicidal poisoning. The external validation of the established nomograms ensured their performance and reliability for universal applicability in clinical settings. Meanwhile, the remaining 22 nomograms lacking external validation represent promising research opportunities.