Injury Prevention
The epidemiology of case fatality rates for suicide in the northeast

https://doi.org/10.1016/j.annemergmed.2004.01.018Get rights and content

Abstract

Study objective

We examine how method-specific case fatality rates for suicide differ by age and sex.

Methods

Seven northeastern states provided mortality and hospital discharge data (1996 to 2000). Suicide acts were divided into 8 categories according to the method used. For each method, the fraction of acts resulting in death (the method-specific case fatality rate) was calculated. Only suicide acts that resulted in hospitalization or death were included.

Results

Overall, 13% of all suicide acts proved lethal (23% for males compared with 5% for females; 7% for people aged 15 to 24 years compared with 34% for individuals aged ≥65 years). Poisoning with drugs accounted for 74% of acts but only 14% of fatalities; firearms and hanging accounted for only 10% of acts but 67% of fatalities. Firearms were the most lethal means (91% resulted in death), followed by drowning (84%) and hanging (82%). For every means, method-specific case fatality rates were higher for male victims and older individuals. Age and sex were associated with overall case fatality rates primarily because of their association with the distribution of methods chosen.

Conclusion

Our findings are based on suicide acts that result in hospitalization or death and therefore underestimate the actual incidence of suicide acts and overestimate case fatality rates. Nevertheless, we find that age and sex influence overall case fatality rates primarily through their association with methods used, rather than because of variation in method-specific case fatality rates.

Introduction

Most studies of suicide acts have relied on self-reported behavior,1, 2, 3 focused on limited groups,1, 2, 3, 4, 5 or restricted analyses to a small number of the methods used.6 As a result, few studies have reported how the method chosen in a suicide act influences the likelihood of death.7, 8, 9 The earliest report to describe variation by method in the lethality of suicide acts (ie, the method-specific case fatality rate) found that suicide acts in Allegheny County, PA, between 1966 and 1970 were most likely to prove fatal if the act was made with a firearm (case fatality rate 92%, ie, 92% of acts were lethal), by hanging (case fatality rate 78%), or by poisoning with carbon monoxide (case fatality rate 67%). Methods least likely to prove fatal included cutting (case fatality rate 4%) or poisoning with drugs (case fatality rate 11%). Case fatality rates reported in subsequent studies were also highest for suicide acts involving firearms, hanging, and carbon monoxide poisoning and lowest for acts by cutting and poisoning with drugs.8, 9 Others noted that the body part affected can also affect the case fatality rate, at least for firearm-related acts,10 and that compared with male individuals and older individuals, female individuals and younger individuals make up a disproportionate number of all suicide acts but are less likely to use highly lethal methods.8, 9 Little else is known about the extent to which overall and method-specific case fatality rates are modified by individual or ecologic factors previously established to be associated with an increased risk of suicide.11, 12, 13, 14, 15, 16

Editor's Capsule Summary

What is already known on this topic

Most studies of suicide acts are limited as a result of their focus on self-reported behavior, group size, or small number of suicide methods used.

What question this study addressed

Using mortality and hospital admission data from 7 states, specific case fatality rates for suicide attempted by different methods were calculated and compared for differences by age and sex.

What this study adds to our knowledge

Of 8 categories of methods (ie, firearms, hanging, jumping, poisoning by drugs, cutting, drowning, poisoning by gas, and other), firearms were the most lethal means (91% lethal), followed by drowning (84%) and hanging (82%), compared with 2% for drug ingestion. For every method of suicide attempt, case fatality rates were higher for males and older individuals.

How this might change clinical practice

Age and sex influence the proportion of suicide acts that prove lethal primarily because they are related to which methods are chosen. Further study is needed to better understand how age and sex influence this choice.

The objective of this study is to examine how method-specific case fatality rates for suicide differ by age and sex. The present study extends previous work by using more recent data and by describing the extent to which sex- and age-based differences in overall case fatality rates are attributable to differences in the distribution of the methods chosen.

Section snippets

Methods

We use customary nomenclature when referring to suicidal actions, as recommended by O'Carroll et al.17 We refer to any self-inflicted injury, whether fatal or nonfatal, as a “suicide act”; when the act results in death, we label the act a suicide, and when the outcome is nonfatal, we label the act an attempted suicide. The case fatality rate for a particular method is defined as the number of suicides with that method divided by the number of suicide acts with that method (ie, case fatality

Results

Overall, 96% of all hospitalizations with an injury-related principal diagnosis were E-coded (97% for Massachusetts and New Hampshire; 96% for Connecticut, New Jersey, and Rhode Island; 89% for Maine; and 86% for Vermont). Overall (and for each state), less than 1% of all known suicide deaths and less than 2% of all known suicide attempts had E-codes that were nonspecific for the method used (not shown).

We identified 44,831 suicide acts across our 7 states, 5,806 (13%) of which proved fatal (

Discussion

Consistent with select population and self-report studies1, 2, 3, 4, 5, 6, 25 and with previous studies that reported case fatality rates,8, 9 we find that suicide acts are most frequent among women and young adults. The rate of suicide acts in our study is considerably lower than rates reported by studies using self-report data1, 3 but similar to rates reported in studies that use hospital discharge data.4, 5, 8, 9

Method-specific case fatality rates in our study are similar to those previously

Acknowledgements

We thank Cathy Barber, MPA, for helpful comments on the manuscript. We also thank the Departments of Public Health in Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, Rhode Island, and Vermont for supplying hospital discharge and mortality files and for their helpful suggestions throughout.

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    Author contributions: All authors contributed substantially to the conception of the design of the study, its analysis, and interpretation. MM wrote the paper. DA and DM critically reviewed and contributed to the shaping and writing of the paper. All authors take responsibility for the paper as a whole.

    Supported in part by grants from the Joyce Foundation and the Centers for Disease Control and Prevention.

    Reprints not available from the authors.

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