title: Prediction of outcome after paraquat poisoning by measurement of the plasma paraquat concentration.
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].
  
  
  CONCLUSIONS
  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.
authors.affiliation: South Asian Clinical Toxicology Research Collaboration, Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka.
authors.forename: L
authors.initials: L
authors.lastname: Senarathna
authors.forename: M
authors.initials: M
authors.lastname: Eddleston
authors.forename: M F
authors.initials: MF
authors.lastname: Wilks
authors.forename: B H
authors.initials: BH
authors.lastname: Woollen
authors.forename: J A
authors.initials: JA
authors.lastname: Tomenson
authors.forename: D M
authors.initials: DM
authors.lastname: Roberts
authors.forename: N A
authors.initials: NA
authors.lastname: Buckley
mesh_terms: D005260:Female; D006540:Herbicides / Q000097:blood / Q000506:poisoning*; D006801:Humans; D008297:Male; D049451:Nomograms; D010269:Paraquat / Q000097:blood / Q000506:poisoning*; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013188:Sri Lanka
chemical_list: D006540:Herbicides; D010269:Paraquat