Potential underestimation of pesticide suicide and its impact on secular trends in South Korea, 1991-2012

Abstract

Background: Pesticide ingestion is among the most commonly used suicide methods globally. Underestimation of deaths by pesticide self-poisoning is thought to be common but under-researched. We investigated potential misclassification and underestimation of suicide by pesticide poisoning and their impact on trends in pesticide suicide in South Korea.

Methods: We compared sociodemographic profiles between deaths certified as suicide, undetermined deaths and injuries by poisoning using pesticides, unspecified chemicals and medicines/alcohol in South Korea (1991-2012), and calculated similarity scores. Joinpoint regression analysis was used to examine time trends.

Results: The profiles of deaths classified as pesticide suicides showed generally similar patterns to those for undetermined deaths/injuries by poisoning using pesticides and suicides/undetermined deaths/injuries by poisoning using unspecified chemicals. Over the study period, the number of pesticide suicides (on average 2033 per year; range 623-3530) would increase by 15%, 23% and 31%, when assuming that 20%, 30% and 40% of deaths in alternative cause-of-death categories were misclassified pesticide suicides respectively. Age-standardised rates of pesticide suicide increased more than four times in 1991-2003 but fell by around 50% in 2003-2012. This trend did not change when the assumed proportion of misclassification was 20%, whereas the rapid increase in 2000-2003 would be lessened if misclassification occurred by 30% or more.

Conclusions: Pesticide suicides may be underestimated in South Korea as some are possibly misclassified as deaths due to other causes; however, such underestimation would not substantially affect estimated secular trends.