Epidemiological trends of suicide and attempted suicide by poisoning in the US: 2000-2008

In the US the suicide rate on a population basis has risen and fallen over time between approximately 10 and 12 per 100,000 population. The recent trend toward an increased rate has been paralleled by an increase in emergency department visits for attempted suicide. The purpose of this study was to examine trends in suspected suicide (SS) cases reported to the National Poison Data System (NPDS), over a 9-year period (2000-2008).

Data were obtained from NPDS, for all human patients between the years 2000 and 2008 with the reason for poisoning exposure recorded as "Intentional - Suspected Suicide" (ISS). Additionally, population sizes were obtained from the US Census Bureau as single annual counts by age and sex bands for the 2000-2008.

There were 1,672,324 human exposures reported to substances with the reason of SS. Sixty-five percent (1,084,669) were female. The average age of a patient was 30 years with the age groups 13-19 and 20-29 years reporting the highest SS events, 26.4% and 25.7%, respectively. From 2000 to 2008, the estimated rate of SS increased from 72.6 to 82.8 per 1000 human exposure cases. On a population basis, the estimated rate of SS increased from 55.8 to 67.9 per 100,000 population (p for trend <0.001). The relative risk of human exposures for reason of SS compared to human exposures for any other reason being reported to the NPDS is 1.13 (95% CI: [1.122-1.135], p < 0.001) for every 10 years. The relative risk for females vs. males was 1.82 for having SS as a reason for exposure (p < 0.001). However, females were also 0.82 times less likely to experience a severe medical outcome (SMO) compared to males (95% CI: [0.81-0.83], p < 0.001). We noted an increasing risk of a SMO or fatality increasing with age.

Based on the total human exposure cases reported to the NPDS, there was a suggested trend of an increase in SS rates of 13% in the next 10 years. There was a greater incidence of SS in females and younger age groups. However, the odds of a SMO or fatality were higher for males and increased with increasing age.