To explore early prognostic value of quantitative detection of paraquat (PQ) plasma concentration and urine sodium dithionite assay for prognosis in patients with acute PQ poisoning.

A prospective study was conducted. The patients with acute PQ poisoning admitted to Department of Emergency of First Hospital of China Medical University from August 2013 to December 2015 were enrolled. At admission, blood samples and urine samples were collected. The PQ plasma concentration was determined by high-performance liquid chromatography (HPLC), and the PQ urine concentration was determined by sodium dithionite, meanwhile the biochemical parameters were determined to carry out sequential organ failure assessment (SOFA) score. According to the prognosis of 90-day follow-up, the patients were divided into survival group and death group. Logistic regression analysis was used to analyze the relationship between the prognosis and the indexes, and the receiver operating characteristic curve (ROC) was drawn to evaluate the prognosis.

There were 148 patients with acute PQ poisoning, with 43 alive and 105 dead, and the 90-day mortality rate was 70.9%. The ingestion volume (mL: 22.69±18.57 vs. 9.91±4.61), plasma concentration of PQ (mg/L: 2.28±1.52 vs. 0.91±0.38) and positive rate of urine sodium dithionite (87.6% vs. 14.0%) in death group were significantly higher than those of survived group (all P < 0.01), but no significant differences in gender, age, poisoning time, gastric lavage time between the two groups were found. Significant differences in white blood cell count [WBC (×10⁹/L): 13.45±6.12 vs. 23.03±7.67] and blood lactate [Lac (mmol/L): 1.50±0.45 vs. 8.10±4.51] between survival group and death group were found (both P < 0.01), while no significant difference in SOFA score was found (0.98±0.72 vs. 1.34±1.29, P > 0.05). It was shown by logistic regression analysis that the key factors affecting the prognosis of patients with PQ poisoning were urine sodium dithionite assay [odds ratio (OR) = 8.731, 95% confidence interval (95%CI) = 2.828-26.954, P = 0.000], PQ plasma concentration (OR = 2.082, 95%CI = 1.204-3.603, P = 0.009) and ingestion volume (OR = 1.175, 95%CI = 1.048-1.318, P = 0.006) respectively. It was shown by ROC curve that the area under ROC curve (AUC) of plasma PQ concentration, urine sodium dithionite assay, poisoning dose and SOFA score for predicting the prognosis in patients with acute PQ poisoning was 0.866, 0.857, 0.826, and 0.631 respectively (all P < 0.05). The sensitivity of urine sodium dithionite assay for predicting the prognosis was 87.6%, and the specificity was 83.7%.

Early plasma PQ concentrations can objectively reflect the body absorbed toxicant doses and actual situation after poisoning, and help to judge the early evaluation of prognosis. The accuracy of urine sodium dithionite assay in judging the prognosis of PQ poisoning is high. Because of its simplicity and availability, it was easier to be performed in the primary hospital.

Paraquat; Poisoning; Paraquat plasma concentration; Sodium dithionite assay; High-performance liquid chromatography; Early evaluation