Distinct psychopathology of patients who attempted suicide with rodenticide in Taiwan: a comparative study with patients of suicide with paraquat

Chemin Lin,1,2 Tzung-Hai Yen,2,3 Yeong-Yuh Juang,4 Chin-Pang Lee,2,5 Shwu-Hua Lee2,5 1Department of Psychiatry, Keelung Chang Gung Memorial Hospital, Taoyuan, Taiwan; 2School of Medicine, Chang Gung University, Taoyuan, Taiwan; 3Department of Nephrology, Clinical Poison Center, Chang Gung Memorial Hospital, Linkou, Taiwan; 4Department of Psychiatry, Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan; 5Department of Psychiatry, Linkou Chang Gung Memorial Hospital, Taoyuan, Taiwan Objective: Rodenticide as a means of suicide has been documented for centuries. However, this method is often discussed in conjunction with other pesticides. Thus, we aimed to focus on patients who committed suicide with rodenticide and compared them with those who used paraquat for suicide, another frequently used yet lethal method, to highlight the different psychopathology of patients who choose rodenticide as their means of suicide. Methods: A 12-year retrospective chart review was conducted on the medical records of all patients admitted to Chang Gung Memorial Hospital due to attempted suicide by either rodenticide or paraquat. Psychiatric consultation sheets were collected to ascertain the psychiatric comorbidity and the major stressor for suicide, measured by the Social Readjustment Rating Scale. A χ2 test and logistic regression were used for group comparisons. Results: Seventeen rodenticide and 157 paraquat suicide attempts were identified. Compared with suicides by paraquat, suicides by rodenticide had a more even distribution in the gender ratio but a lower Social Readjustment Rating Scale score (p<0.001). Depressive disorder was the most common diagnosis in suicides by rodenticide and paraquat. However, schizophrenia and psychotic disorder (29.4%) was the second most common diagnosis and a significant predictor of suicide by rodenticide (odds ratio =9.21, 95% confidence interval =1.2–66.07, p=0.027). Conclusion: High comorbidity of psychosis in suicide by rodenticide warrants disease-specific suicide prevention and additional large-scale research to confirm this association. Keywords: rodenticide, paraquat, suicide, major depression, schizophreni