Predictors of Suicide Attempt Within 30 Days After First Medically Documented Suicidal Ideation in U.S. Army Soldiers

Soldiers with suicidal ideation (N=11,178) were primarily male (81.7%), 29 years old or younger (84.8%), White (71.7%), high school educated (65.7%), never married (52.7%), and younger than 21 years old when they first entered the Army (64.1%) (Table 1). Approximately half of the soldiers (52.7%) were in their first 2 years of service, 57.7% had never deployed, and 27.3% were assigned to combat arms. The five most common psychiatric diagnoses among all soldiers with suicidal ideation were depression-related diagnostic categories (dysthymic disorder, neurasthenia, depression not otherwise specified, and adjustment disorder with depressed mood [58.98% on day of ideation; 43.16% prior to day of ideation]; and major depression [24.17% on day of ideation]), tobacco use disorder (35.68% prior to day of ideation), anxiety disorder (33.56% prior to day of ideation), and adjustment disorder (24.65% prior to day of ideation) (see Table S7 in the online supplement). The majority of soldiers with ideation (80.2%) had at least one day with an outpatient health care visit in the past 2 months. About one-fourth (23.7%) of soldiers with ideation were perpetrators of a crime (mostly minor, nonviolent offenses); 8.8% were victims of a crime prior to their first ideation; and 5.5% had a history of family violence as a perpetrator (4.1%) or as a victim (1.4%) (see Table S8 in the online supplement).

Among the 11,178 soldiers with suicidal ideation, 830 (7.4%) subsequently attempted suicide. As shown in Figure 1, nearly half (46.3%, N=387) attempted suicide within 30 days of their ideation. Figure 2 shows the hazard function indicating that soldiers were at the highest risk of attempting suicide in the first month after ideation (rate, 35.4 per 1,000 soldiers), with incrementally decreasing risk over time. Examination by day showed that the first day had the highest daily risk (rate, 10.1 per 1,000 soldiers).

To our knowledge, no other studies have examined soldiers with documented suicidal ideation and risk of attempt in the following 30 days to understand the progression from ideation to attempt. Identification of factors that may be predictive of suicide attempt provides information for mental health assessment that could help reduce the risk of imminent suicide attempt. In this study, 7.4% of soldiers with ideation subsequently attempted suicide. Nearly half of these attempts (46.3%) were within 30 days after ideation, with attempt risk highest soon after suicidal ideation diagnosis and decreasing over time. Importantly, the rates indicate that more than 3.5% of soldiers with ideation attempted suicide in the month after suicidal ideation diagnosis.

Women and combat medics were at increased risk of attempt within 30 days of first ideation diagnosis, and Black race was associated with lower risk. Women and combat medics have previously been identified as having a higher rate of attempt (27). The present study adds to these earlier findings, highlighting the particular importance of the risk shortly after the diagnosis of ideation. Women, younger individuals, White race, and sleep and anxiety disorders were found to be associated with higher risk of attempt within 30 days, similar to previous findings in military (7) and civilian populations (8, 10, 28, 29). Combat medics have been identified as being at elevated risk of attempting suicide in their first year of service (27), possibly associated with the challenges of advanced training and high performance demands. Previous research also supports the finding of lower attempt risk among Black soldiers for all suicide attempts, not only those associated with ideation (13). Although these differences are not well understood, some researchers have suggested that they may reflect the protective role of cultural and family ties and spiritual/religion-based coping strategies (29). Further research is needed to understand why these demographic and service-related characteristics act as risk or protective factors, and to identify various life events and transitions (e.g., new assignments, transitions out of training, stressful duty assignments, or deployment departures or returns) that may be associated with rapid transition to suicide attempt after ideation. Such information can help identify opportunities for early intervention.

In this study, three psychiatric diagnoses, on the day of suicidal ideation or prior to ideation, were associated with attempt. Soldiers diagnosed with a sleep disorder on the same day as ideation were more likely to attempt suicide within 30 days. This may reflect a new-onset stress-related sleep disorder and be an indicator of acute distress. Anxiety disorder diagnosed prior to ideation (i.e., a history of anxiety disorder) was also associated with increased risk of attempt, while anxiety disorder diagnosed on the same day as ideation was associated with decreased risk. This variation in the influence of anxiety disorders on attempt risk is important and has not previously been observed. Anxiety associated with depression (agitated depression) has been noted as a risk factor for suicidal behaviors (30–32). This may be reflected in the finding of a history of an anxiety disorder prior to ideation being associated with increased attempt risk. This finding also corresponds with that of the community survey research in the National Comorbidity Study (9) and the World Health Organization’s World Mental Health Surveys (10). The diagnosis of anxiety disorder on the same day of suicidal ideation associated with decreased risk is unexpected. One possible explanation might be that an anxiety disorder diagnosis on the same day as ideation may have led clinicians to a rapid intervention (e.g., psychiatric treatment and/or prescription of an anxiolytic), mitigating risk of attempt. Examination of these factors and how they may influence the association of anxiety disorder diagnosis with suicide attempt is important and merits further attention. Additional differences related to the neurobiology of anxiety and suicide-related emotion regulation are yet to be found. Future research should address these complex relationships and identify the role of treatment.

Neither posttraumatic stress disorder (PTSD) nor depression-related diagnoses were associated with increased risk of 30-day suicide attempt in those with ideation. Major depression was identified in 24% of soldiers on the same day as ideation and in 15% prior to ideation. The additional disorders characterized by depressed mood (dysthymic disorder, neurasthenia, depression not otherwise specified, and adjustment disorder with depressed mood) were identified in nearly 60% of soldiers on the same day as ideation and in 43% prior to the day of ideation. The high prevalence of these disorders suggests that they may be associated with ideation in some soldiers, but they do not appear to distinguish those who attempt suicide shortly after diagnosed ideation. The stressors/adversities diagnoses, in contrast to previous studies (33–35), were not related to attempt among soldiers with ideation, suggesting that these broad diagnostic categories (V codes) may not capture more nuanced assessments of life context.

Research examining the risk of attempts or suicides among individuals with suicidal ideation is important to clinical care, yet it has been relatively less studied. In a previous case-control survey study of hospitalized suicide attempters, soldiers with ideation who self-reported PTSD in the past 30 days were more likely to attempt suicide (20). This differs from the present study and represents the value of self-report in potentially identifying undiagnosed or documented psychiatric disorders. Similarly, in a large psychological autopsy study of Army soldiers who died by suicide (36), using interviews with next of kin and supervisors, an internalizing disorder or three or more diagnoses in the past month distinguished soldiers with suicidal ideation from those who died from suicide. Importantly, less than 2% of studies examining suicide specifically focus on imminent risk factors (e.g., within the month prior) (37). Future research should consider the contributions of specific psychiatric disorders in the context of different time frames of risk to better understand rapidly developing suicide attempt.

Several limitations should be considered in the interpretation of the study findings. First, this study used administrative records. Thus, the identified cases are subject to classification and coding errors and are limited to events that come to the Army’s attention. As identification of suicidal ideation cases has important clinical implications, efforts to address under-ascertainment and to detect predictors of imminent attempt would help move individuals to timely and appropriate interventions. Although the extent to which attempts are accurately captured in military medical records cannot be conclusively identified (similar to civilian care settings), a substantial number of at-risk soldiers were documented. Further, examination of diagnoses identified through records as opposed to survey data suggests that some suicidal ideation and attempts, psychiatric disorders, and crime and family violence data are not reported or may have been recorded only in clinical notes, and therefore were not captured in administrative records. Future analyses of Army STARRS survey data that are linked to respondents’ administrative records can allow for examination of undiagnosed psychiatric disorders, subthreshold disorders, and undocumented stressful events among soldiers with self-reported suicidal ideation and those with no documented psychiatric disorders. Second, our injury variable may have captured injuries that were self-inflicted but unrecognized as such. Third, our data in this study focus exclusively on the 2006–2009 period, and therefore our findings may not generalize to other time periods. Research to replicate these findings using different military cohorts or registries is recommended and should include the Army National Guard and Army Reserve soldiers, as well as veterans.

Importantly, this study identified factors predicting acute suicide attempt risk among soldiers with suicidal ideation, highlighting the significance of rapid transition from ideation to attempt and possible needed clinical intervention or follow-up. Those who attempt suicide in the 30 days following ideation include soldiers with an anxiety disorder diagnosis prior to their ideation or a sleep disorder diagnosis identified on the day of ideation. We have also identified two populations of particular importance, given their increased risk for rapid transition from ideation to attempt, namely, combat medics and women.

Although the majority of soldiers who attempt suicide have no history of administratively documented ideation, there is a significant minority whose suicidal thoughts are diagnosed prior to their attempt. This group is particularly important to the health care system as they fall within the purview of clinicians who assess suicide risk and deliver evidence-based treatments. Developing screening tools specifically for suicidal ideation may help identify individuals at imminent risk. Future research should include examination of attempt methods as predictors of imminent attempt risk and the contribution of treatment and treatment-related factors in the transition of ideation to attempt.