Classifying undetermined poisoning deaths

Department of Pediatrics, University of Utah, Salt Lake City, Utah, United States
Injury Prevention (Impact Factor: 1.89). 11/2006; 12(5):338-43. DOI: 10.1136/ip.2005.011171
Source: PubMed


To classify poisoning deaths of undetermined intent as either suicide or unintentional and to estimate the extent of underreported poisoning suicides.
Based on 2002 statewide death certificate and medical examiner data in Utah, the authors randomly selected one half of undetermined and unintentional poisoning deaths for data abstraction and included all suicides. Bivariate analyses assessed differences in demographics, death characteristics, forensic toxicology results, mental health history, and other potentially contributing factors. Classification and regression tree (CART) analysis used information from unintentional and suicide poisoning deaths to create a classification tree that was applied to undetermined poisoning deaths.
The authors analyzed 41 unintentional, 87 suicide, and 84 undetermined poisonings. Undetermined and unintentional decedents were similar in the presence of opiates, physical health problems, and drug abuse. Although none of the undetermined decedents left a suicide note, previous attempt or intent to commit suicide was reported for 11 (13%) of these cases. CART analysis identified suicidal behavior, drug abuse, physical health problems, depressed mood, and age as discriminating between suicide and unintentional poisoning. It is estimated that suicide rates related to poisoning are underreported by approximately 30% and overall suicide rates by 10%. Unintentional poisoning death rates were underreported by 61%.
This study suggests that manner of death determination relies on circumstance dependent variables that may not be consistently captured by medical examiners. Underreporting of suicide rates has important implications in policy development, research funding, and evaluation of prevention programs.

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Available from: Gitte Larsen, Sep 25, 2014
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    • "Third, death certificate data for poisonings have known shortcomings that we have previously articulated [31], [44], [45]. One concern is the classification of intent of death [46], [47]. In order to avoid these shortcomings we chose to include all deaths with a toxicology code for methadone, including unintentional and intentional poisonings. "
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    • "An analysis of data for 13 states from the NVDRS and the National Vital Statistics System inferred that wide variation in classification of poisoning deaths under injury of undetermined intent impaired comparability of suicide and unintentional injury mortality rates [26]. A study of death certificate and medical examiner data for Utah estimated that the unintentional poisoning mortality rate and overall suicide rate were underreported by 61 percent and 10 percent, respectively [27]. A corresponding estimate of underreporting in the poisoning suicide rate was 30%. "
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    ABSTRACT: Two counter trends in injury mortality have been separately reported in the US in recent times - a declining suicide rate and a rapidly rising unintentional poisoning mortality rate. Poisoning suicides are especially difficult to detect, and injury of undetermined intent is the underlying cause-of-death category most likely to reflect this difficulty. We compare suicide and poisoning mortality trends over two decades in a preliminary assessment of their independence and implications for suicide misclassification. Description of overall and gender- and age-specific trends using national mortality data from WISQARS, the Web-based Injury Statistics Query and Reporting System, maintained by the Centers for Disease Control and Prevention (CDC). Subjects were the 936,633 residents dying in the 50 states and the District of Columbia between 1987 and 2006 whose underlying cause of death was classified as suicide, unintentional poisoning, or injury mortality of undetermined intent. The official US suicide rate declined 18% between 1987 and 2000, from 12.71 to 10.43 deaths per 100,000 population. It then increased to 11.15 deaths per 100,000 by 2006, a 7% rise. By contrast to these much smaller rate changes for suicide, the unintentional poisoning mortality rate rose more than fourfold between 1987 and 2006, from 2.19 to 9.22 deaths per 100,000. Only the population aged 65 years and older showed a sustained decline in the suicide rate over the entire observation period. Consistently highest in gender-age comparisons, the elderly male rate declined by 35%. The elderly female rate declined by 43%. Unlike rate trends for the non-elderly, both declines appeared independent of corresponding mortality trends for unintentional poisoning and poisoning of undetermined intent. The elderly also deviated from younger counterparts by having a smaller proportion of their injury deaths of undetermined intent classified as poisoning. Poisoning manifested as a less common method of suicide for this group than other decedents, except for those aged 15-24 years. Although remaining low, the undetermined poisoning mortality rate increased over the observation period. The official decline in the suicide rate between 1987 and 2000 may have been a partial artifact of misclassification of non-elderly suicides within unintentional poisoning mortality. We recommend in-depth national, regional, and local population-based research investigations of the poisoning-suicide nexus, and endorse calls for widening the scope of the definition of suicide and evaluation of its risk factors.
    BMC Public Health 11/2010; 10:705. DOI:10.1186/1471-2458-10-705 · 2.26 Impact Factor
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    • "In contrast to undetermined suicide, suicide appeared to be unrelated to the number of drugs abused. Similarities between suicides and undetermined suicides have been proclaimed [42], but, on the other hand, depression has been shown to discriminate between suicide and undetermined cases in one study [43]. The discrepancy shown in the present study indicates that different mechanisms may be related to suicide and undetermined suicide. "
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