ATG has had a service support contract with the Walter Reed Army Institute of Research (WRAIR) for over 15 years. ATG personnel include epidemiologists and statisticians who support and collaborate with the WRAIR researchers. ATG staff are all at the master’s or doctoral level of training, and they assist in the design, analysis, interpretation and presentation of studies, and in writing and publishing of manuscripts for peer-reviewed journals. There is no financial or other conflict of interest between ATG staff and any of the research with which they participate. ATG and its staff members are contractors with no vested interests in the results, conclusions, and recommendations resulting from any research and have no interests related to employment, consultancy, patents, products in development or marketed products, or any other aspect of this research. Even though Natalya S. Weber, M.D., M.P.H., is a PLOS One Editorial board member, this does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials.
Conceived and designed the experiments: NSW DNC JAF TTP DN. Performed the experiments: NSW DNC JAF DN. Analyzed the data: NSW JAF. Contributed reagents/materials/analysis tools: NSW JAF. Wrote the paper: NSW JAF DNC DN TTP RAL.
Suicide claims over one million lives worldwide each year. In the United States, 1 per 10,000 persons dies from suicide every year, and these rates have remained relatively constant over the last 20 years. There are nearly 25 suicide attempts for each suicide, and previous self-directed violence is a strong predictor of death from suicide. While many studies have focused on suicides, the epidemiology of non-fatal self-directed violence is not well-defined.
We used a nationally representative survey to examine demographics and underlying psychiatric disorders in United States (US) hospitalizations with non-fatal self-directed violence (SDV).
International Classification of Disease, 9th Revision (ICD-9) discharge diagnosis data from the National Hospital Discharge Survey (NHDS) were examined from 1997 to 2006 using frequency measures and adjusted logistic regression.
The rate of discharges with SDV remained relatively stable over the study time period with 4.5 to 5.7 hospitalizations per 10,000 persons per year. Excess SDV was documented for females, adolescents, whites, and those from the Midwest or West. While females had a higher likelihood of self-poisoning, both genders had comparable proportions of hospitalizations with SDV resulting in injury. Over 86% of the records listing SDV also included psychiatric disorders, with the most frequent being affective (57.8%) and substance abuse (37.1%) disorders. The association between psychiatric disorders and self-injury was strongest for personality disorders for both males (OR = 2.1; 95% CI = 1.3–3.4) and females (OR = 3.8; 95% CI = 2.7–5.3).
The NHDS provides new insights into the demographics and psychiatric morbidity of those hospitalized with SDV. Classification of SDV as self-injury or self-poisoning provides an additional parameter useful to epidemiologic studies.
Suicide claims over one million lives worldwide each year
There are nearly 25 suicide attempts for each suicide, and previous suicidal and non-suicidal self-directed violence is a strong predictor of death from suicide
In this cross-sectional study, we examined psychiatric disorders and demographic characteristics of hospitalizations with diagnoses of non-fatal self-directed violence. An emphasis was placed on identifying risk factors for self-directed violence resulting in injury, which may reflect a higher degree of intent to die, compared to poisoning. To our knowledge, this is the first study examining psychiatric disorders and methods of non-fatal self-directed violence in a sample representative of all US hospitalizations.
The National Hospital Discharge Survey (NHDS) is conducted annually by the National Center for Health Statistics
Demographic characteristics and analyses are presented for the total estimated number of discharges (285 million) based on the sample of 2,516,113 weighted records. Because our study examines and compares a disease burden in the hospitalized population, the discharge records associated with normal childbirth (ICD-9 code V27) were excluded. Only those aged 6 years or older and discharged alive were included.
We use the term ‘self-directed violence’ or ‘SDV’ to replace the analogous ICD-9 E95 code definition of ‘suicide and self-inflicted injury.’ This terminology has recently been developed by the US National Center for Injury Prevention and Control in order to promote and improve the consistency of suicidal behavior surveillance and research
Hospitalizations with SDV were ascertained based on at least one supplementary ICD-9 code E950–E959 (suicide and self-inflicted injury) in the NHDS records, which lists between one and seven diagnoses. This section of the ICD-9 covers ‘injuries in suicide and attempted suicide’ and ‘self-inflicted injuries specified as intentional.’ SDV by poisoning was indicated by codes E950 (‘solid or liquid substances’), E951 (‘gases in domestic use,’ e.g., gas distributed by pipeline), or E952 (‘other gases and vapors,’ e.g., motor vehicle exhaust gas), while SDV resulting in injury was specified by codes E953 (‘hanging, strangulation, and suffocation’), E954 (‘submersion’), E955 (‘firearms, air guns, and explosives’), E956 (‘cutting and piercing instrument’), E957 (‘jumping from high places’), or E958 (‘other and unspecified means’). If a discharge record had E95 codes in both categories, the record was classified as SDV resulting in injury. Records with an ICD-9 code 290–319 in any diagnostic position were classified as having an underlying psychiatric disorder. Further classifications into general psychiatric disorders were also considered for analysis. These categories included: psychotic (ICD-9 290–295, 297–299), affective (ICD-9 296, 311), adjustment (ICD-9 309), anxiety (ICD-9 300), personality (ICD-9 301), and substance abuse disorders (ICD-9 303–305)
The statistical analyses were performed using SAS software (version 9.2, SAS Institute Inc, Cary, NC, USA). The NHDS variable “weight” was used to provide national estimates (weighted frequencies) for demographic characteristics, region, source of payment, and length of stay for hospital discharges. Because some values for race were not recorded until beginning in 2000 and others too small to weight, we limited the reported values to ‘Black,’ ‘White,’ ‘Other,’ and ‘Not Stated.’ Ethnicity was not available. We calculated proportions (%) of discharge records with SDV among all discharges and compared them by demographic groups. Odds ratios from logistic regression with 95% confidence intervals (CI), adjusted for sex, age, race, region, and year, were used as measures of comparison and significance.
Time trends examining the counts and rates of SDV resulting in poisoning (E95.0–E95.2) or injury (E95.3–E95.8) were examined over the time period. Rates were estimated using US census data. Mean days of hospital care were also compared between discharges with indications of either injury or poisoning.
Proportions of psychiatric disorders among the hospitalized with and without SDV were calculated and compared stratified by gender. The proportion of discharge records that lists SDV resulting in injury was also presented for each grouping of psychiatric disorders. Discharges with SDV were further examined on the four and five digit ICD-9 levels to explore the most common methods of self-harm and their distribution between genders.
The NHDS sample included 10,908 records with SDV, 0.5% of all records in the sample, representative of 1.4 million total hospital SDV discharges during the study period. The proportion of discharges with SDV remained relatively stable, with 4.5 to 5.7 hospitalizations per 10,000 persons per year (
SDV; self-directed violence.
Important differences in the risks of SDV in general and among the subset of SDV resulting in injury are presented in
Proportion of Hospital Discharges with SDV | SDV Discharges with Self-Injury | SDV Discharges with Self-Poisoning | ||||
% | N | % | N | % | ||
|
Female | 0.54 | 122,330 | 47.9 | 727,726 | 63.0 |
Male | 0.44 | 132,852 | 52.1 | 427,397 | 37.0 | |
|
6–12 | 0.07 | 2,270 | 0.9 | 6,691 | 0.6 |
13–19 | 2.78 | 57,229 | 22.4 | 212,572 | 18.4 | |
20–40 | 1.59 | 125,859 | 49.3 | 576,249 | 49.9 | |
41–65 | 0.43 | 58,772 | 23.0 | 319,759 | 27.7 | |
65–99 | 0.04 | 11,052 | 4.3 | 39,852 | 3.4 | |
|
Black | 0.38 | 17,954 | 7.0 | 106,861 | 9.2 |
White | 0.50 | 152,388 | 59.7 | 745,450 | 64.6 | |
Other | 0.50 | 10,408 | 4.1 | 42,702 | 3.7 | |
Not Stated | 0.55 | 74,432 | 29.2 | 260,110 | 22.5 | |
|
Northeast | 0.39 | 44,559 | 17.5 | 199,488 | 17.3 |
Midwest | 0.56 | 76,635 | 30.0 | 290,608 | 25.1 | |
South | 0.44 | 72,274 | 28.3 | 394,951 | 34.2 | |
West | 0.69 | 61,714 | 24.2 | 270,076 | 23.4 |
SDV vs. All Hospitalized | Self-Injury vs. Self-Poisoning | |||||
OR |
95% CI | OR |
95% CI | |||
|
Female | REF | REF | |||
Male | 0.82 | 0.77–0.88 | 1.96 | 1.65–2.32 | ||
|
6–12 | 4.00 | 2.66–6.02 | 1.34 | 0.54–3.29 | |
13–19 | 76.43 | 63.06–92.64 | 1.06 | 0.67–1.70 | ||
20–40 | 43.38 | 36.05–52.19 | 0.80 | 0.51–1.25 | ||
41–65 | 11.39 | 9.42–13.77 | 0.68 | 0.42–1.09 | ||
> = 65 | REF | REF | ||||
|
Black | REF | REF | |||
White | 1.82 | 1.63–2.03 | 1.23 | 0.92–1.66 | ||
Other | 1.27 | 1.06–1.51 | 1.35 | 0.86–2.13 | ||
Not Stated | 1.56 | 1.39–1.76 | 1.65 | 1.21–2.25 | ||
|
South | REF | REF | |||
Northeast | 0.94 | 0.86–1.03 | 1.15 | 0.90–1.47 | ||
Midwest | 1.46 | 1.34–1.59 | 1.25 | 0.97–1.61 | ||
West | 1.68 | 1.53–1.84 | 1.15 | 0.89–1.49 |
Adjusted for sex, age, race, and region.
Over 86% of the records that listed SDV also included ICD-9 codes for psychiatric disorders. The most common psychiatric disorders associated with SDV were affective disorders (57.8%) and substance abuse disorders (37.1%). Overall, there was a strong association between the co-occurrence of psychiatric disorders and suicide attempts (OR = 14.5; 95% CI 13.2–15.9). The association was strongest for those with affective (OR = 10.4; 95% CI 9.7–11.1) or adjustment (OR = 6.2; 95% CI 5.6–7.0) disorders. Comorbidity differed by sex (
The first two columns of each set represent the proportion of discharges with psychiatric disorders that occur among all hospitalizations or among all SDV discharges, respectively. The third column relates to the method of SDV if a discharge record has the given comorbid psychiatric disorder. The column presents the percentage of SDV discharges with self-injury as opposed to self-poisoning. Error bars are shown if the 95% CI for the weighted sample exceeds 2%.
In all cases, ICD-9 E95 codes were detailed to the fourth or fifth digit, allowing an examination of the methods used for SDV. The majority of E95 codes indicated poisoning, most commonly by solid or liquid substances (81.5%). Among poisonings, the most frequently used substances were ‘tranquilizers and other psychotropic medications’ (37.1%) followed by ‘analgesics, antipyretics, and antirheumatics’ (26.1%). Cutting and piercing (E956) was the most common E95 code classified as a self-injury (11.3%). The distribution of percentages corresponding to method of self-harm differed between males and females. The male to female ratio was largest for discharges with SDV specific to firearms or explosives (OR = 17.9; 95% CI 7.7–41.3).
Although data on suicides in the United States is well maintained by the National Center for Health Statistics, definitive data on non-fatal self-directed violence in general, or suicide attempts in particular, do not exist. Existing studies have primarily relied on self-reports on both national and smaller geographic scales
According to the CDC, the twelve-month incidence of suicide attempts is about 50 per 10,000 individuals
It is important to note that the demographics of individuals who die by suicide differ dramatically from those with suicide attempts. For example, while males have a much higher suicide rate, females are at increased risk for suicide attempts. This gender difference in attempts versus suicides is one of the most widely supported findings in the epidemiology of suicidal behavior
In our population the number and proportion of discharges with SDV were higher among young compared with older individuals. Adolescents are especially vulnerable to stress and depression which may lead to higher rates of suicide attempts
The great majority of hospitalizations with SDV also had psychiatric disorders
While the presence of an affective disorder was the strongest contributor to self-poisoning, a personality disorder was the highest risk factor for self-injury among both males and females. Using means resulting in injury could be attributed to a higher level of aggressiveness and impulsivity among those with personality disorders as well as more pervasive and more resilient psychopathology compared to persons with mood disorders
Among psychiatric hospitalizations the proportion of those with psychoses was substantial and similar for both genders. The proportion of underlying psychosis among discharges with SDV, however, was considerably higher in men compared to women. This gender difference could be attributed to a more severe course of schizophrenia and lower level of social functioning in men
This study was limited by the inability to differentiate between suicide attempts and non-suicidal SDV based on the ICD-9 codes due to the lack of information on suicidal intent. However, we consider it important to study and appropriate to extrapolate our findings to and compare them with the existing literature on suicide attempts because many risk factors are shared by those involved in non-fatal SDV regardless of suicidal intent
Some studies have broader criteria for identifying SDV to include ICD-9 codes E980–E989 (Injuries undetermined whether accidentally or purposefully inflicted)
Our exploration of SDV hospitalizations resulting in either injury or poisoning is useful in understanding how SDV varies among demographic characteristics and among those with certain psychiatric disorders. This may better enable healthcare personnel to be cognizant of this high-risk population. Though demographics and characteristics of the population engaged in SDV differ in many ways, sometimes dramatically, from those that die by suicide, these persons are important as targets of intervention as they are at an increased risk for subsequent suicide.
The authors would like to thank Walter Reed Army Institute of Research, Preventive Medicine Branch staff member Janice K. Gary, for her work in careful review and administrative support in preparation of the manuscripts.
Note the following disclaimer: This work was supported by the Stanley Medical Research Institute, Chevy Chase, MD, and the Department of the Army. The views expressed are those of the authors and should not be construed to represent the positions of the Department of the Army or Department of Defense. None of the authors have any associations, financial or otherwise, that may present a conflict of interest.