Predictors of Suicide Attempt within 30 Days Following First Medically Documented Suicide Ideation in U.S. Army Soldiers

Abstract

Objective:

The current study aims to identify predictors of imminent suicide attempt (within 30 days) among U.S. Army soldiers following their first documented suicide ideation.

Methods:

Using administrative data from the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS), we identified 11,178 active duty Regular Army enlisted soldiers (2006–2009) with medically documented suicide ideation and no prior medically documented suicide attempts. We examined risk factors for suicide attempt within 30 days of first suicidal ideation using logistic regression analyses, including. socio-demographic and service-related characteristics, mental health diagnoses, physical healthcare/injury, and family violence/crime history.

Results:

Among soldiers with first documented suicidal ideation, 830 (7.4%) attempted suicide, 46.3% of whom (n=387) attempted suicide within 30 days (rate 35.4/1000). Following a series of multivariate analyses, our final model identified: Females (OR=1.3[95%CI=1.0–1.8]), combat medics (OR=1.6[95%CI=1.1–2.2]), those with anxiety disorder diagnosis before suicide ideation (OR=1.3[95%CI=1.0–1.6]) and sleep disorder diagnosis on the same day of suicide ideation (OR=2.3[95%CI=1.1–4.6]) were more likely to attempt suicide within 30 days. Black soldiers (OR=0.6[95%CI=0.4–0.9]) and those with anxiety disorder diagnosis on the same day of suicidal ideation (OR=0.7[95%CI=0.5–0.9]) were less likely.

Conclusions:

Suicide attempt risk is highest in the first 30 days following ideation diagnosis, and more likely among women, combat medics, and those with an anxiety disorder diagnosis before suicidal ideation and a same-day sleep disorder diagnosis. Black soldiers and those with a same-day anxiety disorder diagnosis were at decreased risk. These factors may help identify soldiers at imminent suicide attempt risk.

The U.S. Army suicide rate increased substantially during the Iraq and Afghanistan wars, surpassing the civilian suicide rate in 2008 and peaking in 2012.^1–3 Rates of suicidal behavior in the Army remain elevated.^3–5 Identification of risk factors predicting the transition from suicide ideation to suicide attempt can improve clinical care for soldiers at risk of acting on suicidal thoughts. Much of epidemiologic research examining suicide attempt risk among those with ideation is based on survey data.^6–11 These studies make important contributions to understanding risk within community samples. However, it is also important to consider attempt risk in those with medically documented ideation, as these individuals have been detected and are in the healthcare system. To our knowledge, however, electronic healthcare records have not been used to predict suicide attempt among those with documented ideation.

Previous research using Army and Department of Defense (DoD) administrative data found that suicidal behavior is associated with socio-demographic characteristics (e.g., gender, age, education),¹² Army career characteristics (e.g., time in service, deployment status, occupation), mental health diagnosis,^13,14 healthcare utilization (e.g., recent outpatient physical healthcare visits, previous treatment for an injury),^15–17 and crime victimization and perpetration.^18,19 However, it is not known whether these factors distinguish soldiers with documented suicidal ideation who make a subsequent attempt. Army studies using survey data suggest that the transition from ideation to attempt is often rapid,²⁰ with the majority of suicide attempts occurring within one year.^11,21 However, this transition time has not been examined using information within the healthcare system where all soldiers receive care.

To better understand suicidal behaviors among U.S. Army soldiers and identify factors which predict the transition from suicidal ideation to attempt, the current study, using medical records, examines attempt risk in soldiers with ideation to identify the period of highest risk and the proportion of soldiers with ideation who subsequently attempt suicide. We examine predictors of transition of ideation to attempt in the first month following ideation. Specifically, using administrative data from the Army Study to Assess Risk and Resilience in Servicemembers (Army STARRS),²² this study examined socio-demographic and service-related characteristics, mental disorder diagnoses, physical healthcare, and crime and family violence as potential predictors of attempt risk within 30 days of first medically documented suicide ideation.

METHODS

Sample

This study used data from the Army STARRS Historical Administrative Data Study (HADS), integrating 38 Army and DoD administrative data systems in which suicidal events are medically documented, including de-identified, archival Army and DoD records from databases that capture medical, legal, and personnel information during military service. The HADS includes individual-level person-month records for all soldiers on active duty between 1/1/200412/31/2009 (n=1.66 million).²³ This study includes data from 2006–2009. Analysis of the deidentified data was approved by the Institutional Review Boards of the Uniformed Services University of the Health Sciences, University of Michigan Institute for Social Research, University of California, San Diego, and Harvard Medical School.

The HADS contains administrative records for 975,057 Regular Army soldiers on active duty during the study period (excluding activated Army National Guard/Army Reserve). The analytic sample consisted of the 11,178 Regular Army enlisted soldiers with medically documented suicidal ideation during this time. Of this group, 387 had a documented attempt within 30 days (Table 1).

Table 1.

Association of socio-demographic and service-related characteristics of active-duty U.S. Army soldiers with documented suicide attempt within 30 days following initial suicide ideation

		Univariate		Suicide Ideators				Total population (n = 11,178)
				Attempt suicide within 30 daysa (n = 387)		Did not attempt suicide within 30 daysb (n = 10,791)
	χ2	ORc	(95% CIc)	n	%	n	%	%
Socio-demographic Characteristics
Gender
Male		1.0	–	296	76.49	8,834	81.86	81.68
Female		1.4*	(1.1–1.7)	91	23.51	1,957	18.14	18.32
	6.64*
Current Age
< 21		1.8*	(1.1–2.9)	135	34.88	3,203	29.68	29.86
21–24		1.6	(1.0–2.6)	139	35.92	3,813	35.34	35.36
25–29		1.6	(1.0–2.7)	77	19.90	2,106	19.52	19.53
30–34		1.0	–	20	5.17	895	8.29	8.19
35–39		0.8	(0.4–1.8)	10	2.58	531	4.92	4.84
40+		1.1	(0.4–2.8)	6	1.55	243	2.25	2.23
	11.14*
Race/Ethnicity
White		1.0	–	297	76.74	7,715	71.49	71.68
Black		0.6*	(0.4–0.8)	35	9.04	1,556	14.42	14.23
Hispanic		1.1	(0.8–1.6)	43	11.11	1,009	9.35	9.41
Other		0.6	(0.3–1.1)	12	3.10	511	4.74	4.68
	12.14*
Education
< High school		1.2	(1.0–1.5)	132	34.11	3,217	29.81	29.96
High school		1.0	–	239	61.76	7,102	65.81	65.67
Some college		1.1	(0.6–2.3)	9	2.33	234	2.17	2.17
≥ College		0.9	(0.4–1.9)	7	1.81	238	2.21	2.19
	3.62
Marital Status
Never married		1.0	–	206	53.23	5,680	52.64	52.66
Currently married		1.0	(0.8–1.2)	173	44.70	4,848	44.93	44.92
Previously married		0.9	(0.4–1.8)	8	2.07	263	2.44	2.42
	0.14		0.14
Service-related Characteristics
Age at Army entry
< 21		1.1	(0.9–1.5)	259	66.93	6,904	63.98	64.08
21–24		1.0	–	80	20.67	2,465	22.84	22.77
25+		1.0	(0.7–1.5)	48	12.40	1,422	13.18	13.15
	1.19
Time in Service
1–2 years		1.4*	(1.0–1.8)	235	60.72	5,652	52.38	52.67
3–4 years		1.1	(0.8–1.6)	82	21.19	2,486	23.04	22.97
5–10 years		1.0	–	58	14.99	1,950	18.07	17.96
> 10 years		0.6	(0.3–1.1)	12	3.10	703	6.51	6.40
	12.06*
Deployment Status
Never		1.0	–	248	64.08	6,197	57.43	57.66
Current		0.8	(0.5–1.2)	26	6.72	874	8.10	8.05
Previous		0.8*	(0.6–1.0)	113	29.20	3,720	34.47	34.29
	4.98
Demotion
Past year		0.8	(0.6–1.1)	35	9.04	1,177	10.91	10.84
Before past year		0.8	(0.6–1.3)	24	6.20	786	7.28	7.25
Never demoted		1.0	–	328	84.75	8,828	81.81	81.91
	1.95
Delayed Promotion
On Schedule		1.0	–	194	50.13	4,499	41.69	41.98
Late: </= 2 months		1.2	(0.7–2.1)	15	3.88	283	2.62	2.67
Late: > 2 months		0.7	(0.5–1.0)	41	10.59	1,329	12.32	12.26
Not relevant due to rankd		0.7*	(0.6–0.9)	137	35.40	4,680	43.37	43.09
	12.63*
Military Occupational Specialty (MOS)
Combat Armse		1.0	(0.8–1.3)	105	27.13	2,942	27.26	27.26
Combat Medics		1.7*	(1.2–2.3)	40	10.34	710	6.58	6.71
Other MOS		1.0	–	242	62.53	7,139	66.16	66.03
	8.20*

^aSoldiers with first-time documented suicide ideation who subsequently attempted suicide within the next 30 days of recorded ideation

^bSoldiers with first-time documented suicide ideation who did not subsequently attempt suicide within the next 30 days

^cOR = Odds ratio; CI = Confidence interval

^cSoldiers above the rank of E4 are not promoted on a set schedule

^dCombat Arms includes Combat Arms and Special Forces soldiers

^*p < .05

Measures (see Supplement Table S1 for full description)

Suicide ideation and attempt.

Soldiers’ first medically documented episode of suicidal ideation, and those with a suicide attempt within 30 days of ideation were identified. Soldiers attempting suicide within 30 days of their suicidal ideation diagnosis were ‘cases’ and those who did not were ‘controls.’ Classification used administrative records from: the DoDSER,²⁴ a DoD-wide surveillance mechanism, and the ICD-9-CM V62.84 code (suicidal ideation) and E950-E958 codes (self-inflicted poisoning or injury with suicidal intent) from healthcare encounter information from military and civilian treatment facilities, combat operations, and aeromedical evacuations (Table S2, online: www.starrs-ls.org/#/list/publications). Records from different data systems were cross-referenced, ensuring cases represent unique soldiers.

Socio-demographic and service-related characteristics.

Army and DoD administrative records were used to construct socio-demographic (gender, current age, race/ethnicity, education, marital status) and service-related variables (age at Army entry, time in service, deployment status [never, currently, previously], demotion, delayed promotion, and military occupation [combat arms (which includes combat arms and special forces), combat medic, other; Table S3].

Mental health diagnosis.

Administrative medical records identified 28 categories of documented mental disorder diagnoses defined by aggregated ICD-9-CM codes (e.g., attention-deficit/hyperactivity learning disorders [ICD-9-CM codes 314.0–315.9]) and V codes for stressors/adversities (V40.0-V40.9, V61-V61.9, V62-V62.90) and marital problems (V61.1-V61.12) (Table S4). Each mental disorder was categorized into two time periods, identified by disorders occurring on the same day as the first suicidal ideation diagnosis and those occurring prior to the day of first ideation diagnosis. The indicator variables included each of the ICD-9-CM mental disorder codes and stressors/adversities and marital problems V codes.

Physical healthcare visits and injuries.

Administrative medical records identified number of days with a recent outpatient physical healthcare visit (previous two months¹⁸), presence and recency of outpatient and inpatient visits for previous injury, and combat injury-related visits.

Family violence and crime.

Family violence victimization and perpetration history (e.g., physical, sexual, or emotional abuse of spouse or child) were assessed using legal records, the Army Central Registry (a Family Services data system capturing family violence-related events), and medical (ICD-9-CM) records (Tables S5, S6; details reported elsewhere¹⁹). We constructed variables for: any history of family violence; number of family violence events; time since most recent family violence event (i.e., number of months, not including month of suicide attempt or sampled control person-month); and role in family violence events (perpetrator, victim only). We created variables that indicated crime perpetration or victimization separately by examining legal records for which the Army found sufficient evidence to warrant investigation (Table S7).

Statistical Analysis

All analyses were conducted using SAS version 9.4.²⁵ Initially, the associations of all socio-demographic and service-related characteristics, mental disorders, recent physical healthcare visits, and family violence and crime history with suicide attempt within 30 days of soldiers’ ideation were examined using univariate logistic regression. This time frame was determined to identify imminent attempt risk, and accounted for 46.3% of all attempts in this sample. A series of multivariate logistic regression analyses were conducted for each primary predictor above, adjusting for socio-demographics and service-related characteristics. A final model was conducted including only those variables that were significant in the separate multivariate analyses that adjusted for socio-demographics and service-related variables. This model building approach was based on purposeful selection of factors to identify the most parsimonious model that includes all relevant variables of imminent suicide attempt risk.²⁶ The significance threshold for all analyses was set at p < .05, with selected variables for the final model identified by this criterion, as recommended,²⁶ versus correction for multiple comparisons.

Logistic regression coefficients were exponentiated to obtain odds-ratios (OR) and 95% confidence intervals (CI). Because the suicide attempt rate increased during the Iraq and Afghanistan wars,³ each logistic regression equation controlled for calendar month and year. Coefficients of other predictors can consequently be interpreted as averaged within-month associations based on the assumption that effects of other predictors do not vary over time. Stability of predictors of suicidal behaviors over time has been previously documented in this population.² To examine suicide attempt risk as a function of time, we used discrete-time hazard function, with analyses estimating attempt risk by days since first documented ideation. Area under the curve (AUC), Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC) were calculated to evaluate model fit.

RESULTS

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 two years of service, 57.7% had never deployed, and 27.3% were assigned to combat arms. The five most common mental disorder diagnoses among all soldiers with suicidal ideation were: depression-related diagnostic categories (i.e., dysthymic disorder/neurasthenia/depression NOS/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) (Table S8). The majority of soldiers with ideation (80.2%) had at least one day with an outpatient healthcare visit in the past two months. About one-fourth (23.7%) of soldiers with ideation were perpetrators of a crime (mostly minor, non-violent 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 victim (1.4%) (Table S9).

Among the 11,178 soldiers with suicidal ideation, 830 (7.4%) soldiers subsequently attempted suicide. Nearly half (46.3%, n=387) attempted suicide within 30 days of their ideation (Figure 1). 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 the first day had the highest daily risk (10.1 per 1,000 soldiers).

Figure 1.

Cumulative percent of suicide attempts across days since first documented suicide ideation

Figure 2.

Risk of suicide attempt among Regular Army-enlisted soldiers following first documented suicide ideation

Socio-demographic and service-related risk factors

In univariate analyses, ideators were more likely to attempt suicide within 30 days if they were female (χ²₁=6.64, OR=1.4[95%CI=1.1–1.7]) and younger than 21 years old (χ²₅=11.14, OR=1.8[95%CI=1.1–2.9]), and less likely if they were Black (χ²₃=12.14, OR=0.6[95%CI=0.4–0.8]) (Table 1). Soldiers with 1–2 years of service (χ²₃=12.06, OR=1.4[95%CI=1.0–1.8]) and combat medics (χ²₂=8.20, OR=1.7[95%CI=1.2–2.3]) were more likely to attempt. Delayed promotion was not associated with increased attempt risk.

Mental disorder diagnosis, physical healthcare, family and crime risk factors

Univariate analyses indicated that soldiers who were diagnosed with an anxiety disorder on the same day as ideation were less likely to attempt suicide within 30 days (χ²₁=4.54, OR=0.7[95%CI=0.5–1.0]) and those diagnosed with a sleep disorder on the same day were more than twice as likely to attempt suicide (χ²₁=4.36, OR=2.1[95%CI=1.0–4.1]) (Table 2; Table S8). Soldiers with marital problems prior to their ideation were less likely to attempt within 30 days of ideation (χ²₁=5.69, OR=0.7[95%CI=0.5–0.9]). Physical healthcare and injury-related factors (frequency of outpatient physical healthcare visits in the past months, injury-related healthcare visits, and combat injury; Table 2; Table S9) and family violence and crime-related factors (Table S9) were not significantly related to 30-day attempt.

Table 2.

Association of mental and physical health characteristics of active-duty U.S. Army soldiers with documented suicide attempt within 30 days following initial suicide ideation

		Univariate			Multivariatec		Suicide Ideators				Total population (n = 11,178)
							Attempt suicide within 30 daysa (n = 387)		Did not attempt suicide within 30 daysb (n = 10,791)
	χ2	ORd	(95% CId)	χ2	OR	(95% CI)	n	%	n	%	%
Mental Health Diagnosis
Anxiety Disorder (Day of SI)
Yes		0.7*	(0.5–1.0)		0.7*	(0.5–1.0)	54	13.95	1,977	18.32	18.17
No		1.0	–		1.0	–	333	86.05	8,814	81.68	81.83
	4.54*			4.60*
Anxiety Disorder (Prior to SI)
Yes		1.2	(1.0–1.5)		1.3*	(1.0–1.6)	141	36.43	3,610	33.45	33.56
No		1.0	–		1.0	–	246	63.57	7,181	66.55	66.44
	2.42			4.10*
Sleep Disorders (Day of SI)
Yes		2.1*	(1.0–4.1)		2.2*	(1.1–4.3)	9	2.33	127	1.18	1.22
No		1.0	–		1.0	–	378	97.67	10,664	98.82	98.78
	4.36*			4.70*
Injury-Related Healthcare Visit
Recency of injury-related outpatient or inpatient visit
1 month		1.3	(1.0–1.8)		1.4*	(1.1–1.9)	122	31.52	2,819	26.12	26.31
2 months		0.9	(0.6–1.3)		0.9	(0.6–1.4)	33	8.53	1,158	10.73	10.65
3+ months		1.0	(0.8–1.4)		1.2	(0.9–1.7)	154	39.79	4,498	41.68	41.62
No injury-related visit		1.0	–		1.0	–	78	20.16	2,316	21.46	21.42
	6.87			7.97*

^aCases: Soldiers with first-time documented suicide ideation who subsequently attempted suicide within the next 30 days of recorded ideation

^bControls: Soldiers with first-time documented suicide ideation who did not subsequently attempt suicide within the next 30 days

^cEach variable was examined in a separate multivariate model that adjusted for socio-demographics (gender, current age, race, education, and marital status) and service-related characteristics (age at entry into Army service, time in service, deployment status, delayed promotion, demotion, and military occupation)

^dOR = Odds ratio; CI = Confidence interval

^*p < .05

Multivariate analyses

A multivariate model with socio-demographic and service-related characteristics indicated that soldiers with suicidal ideation were more likely to attempt suicide within 30 days if they were women (χ²₁=6.2, OR=1.4[95%CI=1.1–1.8]), and combat medics (χ²₂=6.8, OR=1.6[95%CI=1.1–2.3]) and were less likely to attempt suicide if they were Black (χ²₃=10.4, OR=0.6[95%CI=0.4–0.9]) (Table S10).

A series of separate multivariate models examining specific mental disorders, adjusting for socio-demographic and service-related variables, indicated that soldiers diagnosed with an anxiety disorder on the day of their ideation were less likely to attempt suicide within 30 days (χ²₁=4.6, OR=0.7[95%CI=0.5–1.0]) and those diagnosed with a sleep disorder on the same day were over twice as likely to attempt suicide (χ²₁=4.7, OR=2.2[95%CI=1.1–4.3]) (Table 2 and Table S11). Solders with a documented anxiety disorder prior to their ideation were more likely to have attempted (χ²₁=4.1, OR=1.3[95%CI=1.0–1.6]). No other mental disorders were significantly associated with attempt. As the anxiety disorder variables (prior to and same day as ideation) had opposite associations with attempt risk, we examined these variables in a model together that took into account their respective effects. Both variables continued to have the same significant association with attempt risk.

Among physical healthcare, family and crime predictors, only recency of last outpatient physical injury visit (χ²₃=7.97, 1 month: OR=1.4[95% CI=1.1–1.9]) was significantly related to suicide attempt, after adjusting for demographics and service-related variables (Table 2; Table S12).

We examined a final model that included all socio-demographic and service-related characteristics and the variables that were significant in the separate multivariate models (i.e., anxiety disorder (prior to suicidal ideation; on the same day as ideation), sleep disorder (on the same day as ideation), and recency of last injury-related outpatient visit) (Table 3). In this model, being female and a combat medic continued to be associated with suicide attempt risk, and Black race was associated with lower risk. Anxiety disorder (prior to ideation) and sleep disorder (same day as ideation) was related to suicide attempt risk, and anxiety disorder (same day as ideation) was associated with lower attempt risk. Recency of outpatient injury-related visit was no longer significantly related to attempt. In a separate model, we examined the influence of both prior and same-day anxiety disorder diagnoses; however, this factor was not associated with suicide attempt risk. The AUC of the final model including all socio-demographic and service-related characteristics and variables that were significant in the separate multivariate models (i.e., anxiety disorder (prior to SI; on the same day as SI diagnosis), sleep disorder (on the same day as SI), and recency of last injury-related outpatient visit) was 0.64, and the AIC and BIC of this final model were 3372.17 and 3730.94, respectively.

Table 3.

Multivariate associations of mental health diagnosis and healthcare factors in active-duty U.S. Army soldiers with documented suicide attempt within 30 days following initial suicide ideation^a

	χ2	OR	(95% CI)
Socio-demographic characteristics
Gender
Male		1.0	–
Female		1.3*	(1.0–1.8)
	4.64*
Current Age
< 21		1.4	(0.7–3.0)
21–24		1.4	(0.7–2.7)
25–29		1.5	(0.8–2.5)
30–34		1.0	–
35–39		0.9	(0.4–1.9)
40+		1.2	(0.5–3.3)
	2.77
Race/ethnicity
White		1.0	–
Black		0.6*	(0.4–0.9)
Hispanic		1.2	(0.8–1.6)
Other		0.6	(0.4–1.2)
	9.98*
Education
< High school		1.1	(0.9–1.4)
High school		1.0	–
Some college		1.3	(0.7–2.6)
≥ College		1.2	(0.5–2.8)
	1.64
Marital status
Never married		1.0	–
Currently married		1.2	(1.0–1.6)
Previously married		1.3	(0.6–2.7)
	3.47
Service-related characteristics
Age at Army Entry
< 21		1.2	(0.8–1.6)
21–24		1.0	–
25+		1.1	(0.7–1.8)
	1.05
Time in Service
1–2 years		1.1	(0.6–2.0)
3–4 years		1.1	(0.7–1.6)
5–10 years		1.0	–
> 10 years		0.7	(0.3–1.6)
	0.95
Deployment Status
Never		1.0	–
Currently		0.9	(0.6–1.4)
Previously		1.0	(0.7–1.4)
	0.22
Demotion
Past year		0.9	(0.5–1.4)
Before past year		1.0	(0.6–1.6)
Never demoted		1.0	–
	0.32
Delayed Promotion
On schedule		1.0	–
Late: </= 2 months		1.2	(0.7–2.2)
Late: > 2 months		0.8	(0.5–1.3)
Not relevant due to rankc		0.7	(0.4–1.2)
	3.18
Military Occupational Specialty (MOS)
Combat Armsd		1.1	(0.8–1.4)
Combat Medics		1.6*	(1.1–2.2)
Other MOS		1.0	–
	6.41*
Mental health diagnosis
Anxiety Disorder (Day of SI)
Yes		0.7*	(0.5–0.9)
No		1.0	–
	6.67*
Anxiety Disorder (Prior to SI)
Yes		1.3*	(1.0–1.6)
No		1.0	–
	5.16*
Sleep Disorders (Day of SI)
Yes		2.3*	(1.1–4.6)
No		1.0	–
	5.47*
Physical healthcare and injury visits
Recency of injury visit (outpatient)
1 month		1.4*	(1.0–1.9)
2 months		0.9	(0.6–1.4)
3+ months		1.2	(0.9–1.6)
No injury-related visit		1.0	–
	6.56

^aAll variables that were significant in separate multivariate models that adjusted for socio-demographics (gender, current age, race, education, and marital status) and service-related characteristics (age at entry into Army service, time in service, deployment status, delayed promotion, demotion, military occupation) were examined together in a final multivariate model.

^bOR = Odds ratio; CI = Confidence interval

^cSoldiers above the rank of E4 are not promoted on a set schedule

^dCombat Arms includes Combat Arms and Special Forces soldiers

^*p < .05

DISCUSSION

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 to reduce the risk of imminent suicide attempt. In the current study, 7.4% of soldiers with ideation subsequently attempted suicide. Nearly half of these attempts (46.3%) were within 30 days of ideation, with attempt risk highest soon after suicidal ideation diagnosis and decreasing over time. Importantly, the rates indicate that more than 3.5 out of one hundred 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.²⁶ This study adds to these 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 associated with higher risk of attempt within 30 days, similar to previous findings in military⁷ and civilian populations.^8,10,28,29 Combat medics have been identified at elevated risk of attempting suicide in their first year of service,²⁷ possibly associated with their 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.³⁰ Although not well understood, some have suggested that these differences 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 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. Such information can help identify opportunities for early intervention.

In the current study, three mental disorder 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., 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 not previously observed. Anxiety associated with depression (agitated depression) has been noted as a risk for suicidal behaviors.^31–33 This may be reflected in this finding of the 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 Study³⁴ and WHO World Mental Health Surveys.³⁵ 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 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 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 (e.g., dysthymic disorder/neurasthenia/depression NOS/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 do not appear to distinguish those who subsequently attempt suicide shortly after 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 completed suicides among ideators is very important to clinical care, yet 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 suicide²⁰. This differs from the present study and represents the value of self-report in potentially identifying undiagnosed or documented mental disorders. Similarly, in a large psychological autopsy study of Army soldiers who died by suicide,³⁹ using interviews with next of kin and supervisors, an internalizing disorder or three or more diagnoses in the past month distinguished ideators from those who died from suicide. Importantly, fewer than 2% of studies examining suicide specifically focus on imminent risk factors, e.g., within the month prior.⁴⁰ Future research should consider the contributions of specific mental disorders in the context of different time frames of risk to better understand rapidly developing suicidal 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 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, similar to civilian care settings, cannot be conclusively identified, a substantial number of at-risk soldiers were documented. Further, examination of diagnoses identified through records versus survey data suggests that some suicidal ideation and attempts, mental disorders, and crimes/family violence are not reported, or may have been identified 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 mental disorders, sub-threshold disorders, and undocumented stressful events among soldiers with self-reported suicidal ideation and those with no documented mental disorders. Second, our injury variable may have captured injuries that were self-inflicted but unrecognized as such. The current study data focus exclusively on the 2006–2009 period, therefore, our findings may not generalize to other time periods. Future research that replicates these findings using different military cohorts and/or registries is recommended and should include the Army National Guard and Army Reserve soldiers, and veterans.

Importantly, this study identified factors predicting acute suicide attempt risk among ideators, highlighting the significance of rapid transition from suicide ideation to suicide 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 due to increased risk for rapid transition from ideation to attempt: 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 latter group is particularly important to the healthcare system as they fall within the purview of clinicians who assess suicide risk and deliver evidence-based treatments. Developing screening tools specifically for those with suicide ideation may help identify those 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.