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Multicenter Study
. 2009 Apr;102(4):251-9.
doi: 10.1093/qjmed/hcp006. Epub 2009 Feb 19.

Prediction of outcome after paraquat poisoning by measurement of the plasma paraquat concentration

L Senarathna  1 , M Eddleston, M F Wilks, B H Woollen, J A Tomenson, D M Roberts, N A Buckley
Affiliations
Multicenter Study

Prediction of outcome after paraquat poisoning by measurement of the plasma paraquat concentration

L Senarathna et al. QJM. 2009 Apr.

Abstract

Background: Paraquat is a herbicide with a good occupational safety record, but a high mortality after intentional ingestion that has proved refractory to treatment. For nearly three decades paraquat concentration-time data have been used to predict the outcome following ingestion. However, none of the published methods has been independently or prospectively validated. We aimed to use prospectively collected data to test the published predictive methods and to determine if any is superior.

Methods: Plasma paraquat concentrations were measured on admission for 451 patients in 10 hospitals in Sri Lanka as part of large prospective cohort study. All deaths in hospital were recorded; patients surviving to hospital discharge were followed up after 3 months to detect delayed deaths. Five prediction methods that are based on paraquat concentration-time data were then evaluated in all eligible patients.

Results: All methods showed comparable performance within their range of application. For example, between 4- and 24-h prediction of prognosis was most variable between Sawada and Proudfoot methods but these differences were relatively small [specificity 0.96 (95% CI: 0.90-0.99) vs. 0.89 (0.82-0.95); sensitivity 0.57 vs. 0.79, positive and negative likelihood ratios 14.8 vs. 7.40 and 0.44 vs. 0.23 and positive predictive values 0.96 vs. 0.92, respectively].

Conclusion: All five published methods were better at predicting death than survival. These predictions may also serve as tools to identify patients who need treatment and for some assessment to be made of new treatments that are trialled without a control group.

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Figures

Figure 1.
Figure 1.
Paraquat concentrations and outcome of patients with paraquat poisoning and Jones, Proudfoot, Scherrmann and Sawada prediction lines. All methods predict those above the lines are more likely to die than survive (filled bullet = death, bullet = alive).
Figure 2.
Figure 2.
Paraquat concentrations and outcome from 277 patients (up to 28-h post ingestion) with paraquat poisoning compared with the probability of survival estimated by Hart's nomogram. (filled bullet = death, bullet = alive).
See this image and copyright information in PMC

References

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    1. Proudfoot AT, Stewart MS, Levitt T, Widdop B. Paraquat poisoning: significance of plasma-paraquat concentrations. Lancet. 1979;2:330–2. - PubMed

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