### Introduction

### Methods

### Patient selection

*n*= 149) and nonsurvival (

*n*= 639). Patients who lived for more than 3 months were included in the survival group. This study was approved by the Institutional Review Board of Presbyterian Medical Center.

### Data collection and study variables

### Examination of plasma PQ concentration

*g*for 15 minutes at 4°C and analyzed at the Christian Medical Research Center. If patients arrived within 4 hours of ingestion, another blood sample (PQ 2 hours) was collected 2 hours later. PQ levels were measured using high-performance liquid chromatography.

### Statistical analysis

*t*test for continuous variables and the chi-square test for categorical variables. Multiple logistic regression analysis was applied to predict the outcome after acute PQ poisoning. In this study, time since ingestion (in hours), serum creatinine, and plasma PQ level were used in multiple logistic regression analysis after logarithmic conversion as they did not display a normal distribution. To determine the sensitivity and specificity of the prediction equation, receiver operating characteristic curves were generated. A

*P*value of < 0.05 was considered statistically significant. Statistical analysis was carried out using SPSS software, version 21 (IBM corporation, New York, NY, USA) and MedCalc 12.5 (MedCalc Software bvba, Mariakerke, Belgium).

### Results

### Baseline characteristics

_{2}and bicarbonate levels were 25 mmHg (range, 3-56 mmHg) and 14.8 mmol/L (range, 2-35 mmol/L), respectively. The mean ingested amount of PQ as estimated with history was 151 mL (range, 5-600 mL), and the initial mean plasma PQ level on admission was 65.23 μg/mL (range, 0.5-833 μg/mL). Of 525 patients who arrived within 4 hours of ingestion, 1 more sample was collected 2 hours later in 379 patients (72.2%), and, of 758 patients (96.2%) in whom a urine dithionite test was performed, 632 patients (83%) showed strong positive results. Of 788 patients, 149 patients (19%) survived.

### Comparison of clinical characteristics between survivors and nonsurvivors

*n*= 149) and nonsurvivors (

*n*= 639), the survivors were younger (47 ± 14 years vs. 59 ± 16 years) and had lower serum creatinine on admission (0.95 ± 0.91 mg/dL vs. 1.88 ± 1.27 mg/dL; Table 3). Survivors also had lower plasma PQ concentrations (0.44 ± 0.70 μg/mL vs. 80.48 ± 123.13 μg/mL; Table 3). Although survivors had a lower amylase level than that of nonsurvivors, there was no difference in serum alanine aminotransferase between the 2 groups. The proportion of positive or strong positive urine tests was much higher in nonsurvivors than in survivors (Table 3).