Predicting outcome in acute organophosphorus poisoning with a poison severity score or the Glasgow coma scale

Abstract

Background: Organophosphorus (OP) pesticide poisoning kills around 200,000 people each year, principally due to self-poisoning in the Asia-Pacific region.

Aim: We wished to assess whether patients at high risk of death could be identified accurately using clinical parameters soon after hospital admission.

Design: We evaluated the usefulness of the International Program on Chemical Safety Poison Severity Score (IPCS PSS) and the Glasgow Coma Score (GCS) prospectively for predicting death in patients poisoned by OP pesticides.

Methods: Data were collected as part of a multicenter cohort study in Sri Lanka. Study doctors saw all patients on admission, collecting data on pulse, blood pressure, pupil size, need for intubation and GCS.

Results: Of the patients, 1365 with a history of acute OP poisoning were included. Receiver operating characteristic (ROC) curves were calculated for the IPCS PSS and GCS on admission. The IPCS PSS and GCS had similar ROC area under the curves (AUC) and best cut points as determined by Youden's index (AUC/sensitivity/specificity 0.81/0.78/0.79 for IPCS PSS > or = grade 2 and 0.84/0.79/0.79 for GCS < or = 13). The predictive value varied with the pesticide ingested, being more accurate for dimethoate poisoning and less accurate for fenthion poisoning (GCS AUC 0.91 compared with 0.69).

Conclusion: GCS and the IPCS PSS were similarly effective at predicting outcome. Patients presenting with a GCS < or = 13 need intensive monitoring and treatment. However, the identity of the organophosphate must be taken into account, since the half of all patients who died from fenthion poisoning only had mild symptoms at presentation.

Figure 1

Receiver operating characteristic (ROC) plot for all OPs comparing the predictive value of GCS, pulse, blood pressure, pupil size and intubation.

Figure 2

ROC plot of the IPCS Poison Severity Score's variable ability to predict death for different OPs.

Figure 3

ROC plot comparing the ability of GCS to predict outcome for different OPs.

Figure 4

Plot of the odds ratios for the best cut offs for the IPCS PSS, GCS, systolic BP, pulse and intubation in the different OPs.

Figure 5

Histogram of the pulse on admission in survivors and deaths.