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Anxiety disorders and suicidality in the National Comorbidity Survey-Replication
Journal of Psychiatric Research 43 (2009) 825–829
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Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/jpsychires
Anxiety disorders and suicidality in the National Comorbidity Survey-Replication Jesse R. Cougle *, Meghan E. Keough, Christina J. Riccardi, Natalie Sachs-Ericsson Department of Psychology, Florida State University, P.O. Box 3064301 Tallahassee, FL 32306, United States
a r t i c l e
i n f o
Article history: Received 22 October 2008 Received in revised form 4 December 2008 Accepted 12 December 2008
Keywords: Anxiety Suicide Depression Risk factors Epidemiology
a b s t r a c t Objective: The current study sought to examine the unique associations between anxiety disorders and suicidality using a large nationally representative sample and controlling for a number of established risk factors for suicide. Method: Data from the National Comorbidity Survey-Replication were used for analyses. Lifetime diagnostic history and demographics were obtained in this survey through a structured interview. Lifetime suicidal ideation and attempts were also assessed. Results: Multivariate analyses covarying for psychiatric comorbidity and demographic variables found social anxiety disorder (SAD), posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), and panic disorder (PD) to be unique predictors of suicidal ideation, while only SAD, PTSD, and GAD were predictive of suicide attempts. Analyses by gender indicated that each of these four disorders were predictive of suicidal ideation or suicide attempts among women, while only PTSD and PD acted as risk factors among men. Conclusions: Findings provide further evidence of the negative impact of anxiety disorders, suggest efforts should be made towards their early detection and treatment, and emphasize the importance of suicide risk assessment in treating individuals with anxiety disorders. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction In the United States alone, 1.3% of all deaths and more than 32,000 deaths per year are by suicide (Center for Disease Control and Prevention, 2005). Efforts to prevent such deaths are aided by the fact that up to 95% of suicides are committed by people with one or more psychological disorders (Cavanagh et al., 2003). If certain disorders are identified as independent risk factors for suicide, then it is likely that treatment of these may lower suicide risk. Indeed, research has found that treatment of depression and bipolar disorder leads to reductions in completed suicides (Rihmer, 2001; Tondo et al., 2001). The psychiatric problems most consistently linked to suicidality are mood disorders and certain categories of personality disorders (e.g., borderline personality disorder). However, research has also accumulated over the past several years indicating that anxiety disorders confer unique risk of suicide. Panic disorder (PD) is one of the anxiety disorders studied most in relation to suicide, though evidence supporting the relationship has been inconsistent. Weismann and colleagues (Weissman et al., 1989) found a strong association between PD and suicidality using data from the epidemiological catchment area study. However, Hornig and
* Corresponding author. Tel.: +1 850 645 8729; fax: +1 850 644 7739. E-mail address: [email protected] (J.R. Cougle). 0022-3956/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpsychires.2008.12.004
McNally (1995) reanalyzed the same data and found this relationship to disappear after controlling for certain comorbid disorders. Comorbidity is an important consideration when evaluating risk factors for suicidal behavior. Psychological disorders rarely occur alone, and anxiety disorders such as posttraumatic stress disorder (PTSD) more often occur with depression (a strong risk factor for suicidality) than without it (Brown et al., 2001). Multivariate tests that include a range of predictors are, thus, necessary. Sareen and colleagues (2005a,b) and Bolton et al. (2008) recently examined the associations between anxiety disorders and suicide in three different studies. In a longitudinal survey, the presence of any anxiety disorder was found to be associated with significant risk for subsequent suicidal ideation and suicide attempts (Sareen et al., 2005a). Though trends were similar for each anxiety disorder in increasing suicide risk, obsessive-compulsive disorder (OCD), generalized anxiety disorder (GAD), and social anxiety disorder (SAD) appeared to be most prominently associated with subsequent suicidal ideation, while simple phobia was most strongly associated with subsequent suicide attempts. Additional analyses indicated that presence of any anxiety disorder with comorbid mood disorder was associated with greater risk of suicide attempts than mood disorder alone. Some of these analyses, understandably, were limited by low statistical power (i.e., there were only 39 cases of new suicide attempts in the follow-up assessments). In addition, PTSD, one of the more prominent predictors of suicidality, was not assessed in their design. In a second study, using data from the
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cross-sectional National Comorbidity Survey (NCS) (Sareen et al., 2005b), these researchers found lifetime PTSD to be the only anxiety disorder acting as a unique predictor of lifetime suicidal ideation and suicide attempts. More recently, using data from the Baltimore epidemiological catchment area survey, investigators found the presence of one or more anxiety disorders to uniquely predict subsequent suicide attempts, though individual anxiety disorders were collapsed into a single variable for their analysis and PTSD was not assessed in this study (Bolton et al., 2008). All of these studies provide valuable contributions to the suicide literature; however, they are limited in certain ways. First, borderline personality disorder, a strong risk factor for suicidal behavior, was not considered in the analyses. In addition, given that the presence of three or more diagnoses is a potent risk factor for suicide (Kessler et al., 1999), Sareen et al. (2005b) included a variable coded for this in their cross-sectional NCS study. Since most predictors were added into this variable and comorbidity is already being taken into account in the analysis, the inclusion of this variable may have artificially reduced the potency of each predictor. Lastly, diagnoses in these studies were assessed using either DSM-III-R (Sareen et al., 2005a,b) or DSM-III (Bolton et al., 2008) criteria. Since significant changes in diagnostic criteria of disorders such as PTSD had been made in the DSM-IV (American Psychiatric Association, 2000), it is important to update these analyses using current criteria. The current study addressed some of the limitations in extant research on anxiety disorders and suicidality using the National Survey of Comorbidity-Replication (NCS-R). The NCS-R is a more recent nationally representative survey than the NCS that includes data on DSM-IV diagnoses and borderline and anti-social personality disorders. Lifetime history of several different anxiety disorders were tested as predictors of lifetime suicidal ideation and attempts. In addition, given that suicidal behavior differs between men and women (Kessler et al., 1999), we conducted further analyses by gender.
2. Methods 2.1. Sample The NCS-R is composed of a representative sample of Englishspeaking adults from the contiguous United States. Participants were interviewed in-person at their place of residence between February 2001 and April 2003. A detailed description of the methodology, weighting and sampling procedures used in the NCS-R have been provided by Kessler and colleagues (Kessler et al., 2005). All respondents completed Part I of the interview (N = 9282) which contained a section covering each of the core mental health disorders. Part II included sections on disorders of secondary importance as well as risk factors, consequences, services and other correlates of mental health disorders. In an effort to reduce respondent burden, Part II was completed only by those who met criteria for a lifetime core diagnosis as well as a probability subsample of those who did not meet criteria. The current investigation was based on data from both Part I and II from which we obtained a subsample of individuals (N = 4131) who reported on lifetime suicidal ideation and suicide attempts. The sample was 56% female with an average age of 49.88 (SD = 16.3). The racial and ethnic representation of the study participants was 73.2% Caucasian, 12.5% African–American, 10.8% Hispanic, and 3.5% from other ethnicities. 3. Procedure Based on the 2000 US Census, a stratified, multistage probability sample was created. Respondents received a letter describing
the survey and their potential participation several days before in-person contact was made. Interviews were conducted by professional interviewers who had obtained extensive training and were closely supervised by the Institute for Social Research. The administration of the interview was completed face-to-face with the assistance of a laptop computer. The interviewers obtained verbal informed consent from each respondent. The consent procedures were approved by the Human Subject Research Committees at Harvard Medical School and the University of Michigan. Respondents received $50 as a token of appreciation for completing the interview. The overall response rate was 70.9%. Part I was weighted to adjust for discrepancies between the sample and the US Census in terms of geographic and sociodemographic variables. Additional weighting of Part II was conducted to adjust for differential probability of selection from Part I (Kessler et al., 2004). 4. Measures Demographic: The interview included an extensive demographic section that assessed sex, age, education, marital status as well as other demographic variables. Diagnostic Assessment: Lifetime anxiety, mood and substance use disorders were assessed using the World Mental Health Survey Initiative version of the World Health Organization Composite International Diagnostic Interview (WMH-CIDI) reference. This is a structured diagnostic interview from which DSM-IV Axis I (American Psychiatric Association, 2000) diagnoses are derived. The CIDI has been found to have good validity and reliability (First et al., 2002). The Axis II diagnoses of anti-social personality disorder (ASPD) and borderline personality disorder (BPD) were evaluated using their respective screening items from the International Personality Disorder Examination which has been shown to have good sensitivity and specificity (Loranger et al., 1994). Cases of ASPD and BPD were identified by computing participant’s continuous scores on the screening items for each disorder and then applying a cutscore based on established lifetime rates (Robins et al., 1991). Suicidality: Respondents’ lifetime history of suicidal ideation and suicide attempts were assessed during the interview. Respondents who reported they had ever ‘‘seriously thought about committing suicide” were coded as having a history of suicidal ideation. Those who endorsed having ‘‘ever attempted suicide” were coded as having a history of suicide attempts. 5. Results All analyses were conducted using Statistical Analysis Software (SAS) version 9.1 and employed the appropriate NCS-R statistical weights to ensure the sample was representative of the general US population. Table 1 presents the results of the univariate associations between lifetime suicidal ideation and attempts and established demographic and diagnostic risk factors. As expected, suicide attempts were significantly associated with each risk factor while suicidal ideation was significantly associated with each risk factor except education. The second set of univariate comparisons examined suicidal ideation and attempts across the different lifetime anxiety disorders (see Table 2). In uncontrolled analyses, each anxiety disorder conveyed a significant risk for both suicidal ideation and suicide attempts. To further assess the risk conveyed by lifetime anxiety disorders by covarying the established demographic and diagnostic risk factors, both the risk factors and the anxiety disorders were entered into a multivariate logistical regression. Social anxiety disorder (SAD), panic disorder (PD), generalized anxiety disorder (GAD) and posttraumatic stress disorder (PTSD) all remained significantly associated with a history of suicidal ideation (see Table 3). Specific
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J.R. Cougle et al. / Journal of Psychiatric Research 43 (2009) 825–829 Table 1 Associations between demographic data, established risk factors and suicidal ideation and suicide attempts.
Total sample Age Gender (Male) Married/cohabiting Education Borderline personality disorder Anti-social personality disorder Bipolar disorder Major depressive disorder
Suicidal ideation N%
OR (95% CI)
Suicide attempts N%
OR (95% CI)
(557/4131) 14.0% – (213/1826) 11.7% (300/2596) 11.6% – (149/347) 42.9% (157/508) 30.9% (44/87) 50.6% (288/774) 37.2%
– 0.98 0.71 0.59 0.94 5.88 3.41 6.79 6.27
(184/4128) 4.5% – (50/1825) 2.7% (81/2596) 3.1% – (72/344) 20.9% (69/505) 13.7% (22/87) 25.3% (108/770) 14.0%
– 0.97 0.46 0.45 0.74 8.60 4.89 8.30 7.04
(0.97–0.98)** (0.60–0.83)** (0.50–0.70)** (0.86–1.02) (4.78–7.24)** (2.69–4.31)** (5.12–9.01)** (5.42–7.25)**
(0.96–0.98)** (0.34–0.63)** (0.35–0.56)** (0.65–0.84)** (6.65–11.13)** (3.59–6.65)** (5.70–12.09)** (5.12–9.68)**
*
p < 0.05. p < 0.01.
**
Table 2 Prevalence of lifetime suicidal ideation and suicide attempts across anxiety disorders with univariate comparisons.
Total sample Agoraphobia without panic Social anxiety disorder Panic disorder ± agoraphobia Generalized anxiety disorder Posttraumatic stress disorder Specific phobia
Suicidal ideation N%
OR (95% CI)
Suicide attempts N%
OR (95% CI)
(557/4131) 14.0% (45/99) 45.5% (164/471) 34.8% (99/251) 39.4% (136/350) 38.9% (120/298) 40.3% (142/525) 27.0%
– 5.43 4.18 4.62 4.81 4.97 2.70
(184/4128) 4.5% (20/99) 20.2% (67/468) 14.3% (43/249) 17.3% (57/348) 16.4% (56/298) 18.8% (57/524) 10.9%
– 5.85 5.07 5.59 5.59 6.68 3.36
(4.02–7.33)** (3.54–4.95)** (3.63–5.86)** (4.02–5.76)** (4.11–6.00)** (2.16–3.39)**
(4.09–8.37)** (3.71–6.93)** (4.11–7.61)** (4.27–7.34)** (5.11–8.74)** (2.43–4.65)**
*p < 0.05. **
p < 0.01.
Table 3 Multivariate logistic regression analysis of lifetime suicidal ideation and suicide attempts. Lifetime suicidal ideation AOR (95% CI) Age Sex Education Married/cohabiting Borderline personality disorder Anti-social personality disorder Bipolar disorder Alcohol abuse or dependence Drug abuse or dependence Major depression Agoraphobia without panic disorder Social anxiety disorder Panic disorder ± agoraphobia Generalized anxiety disorder Posttraumatic stress disorder Specific phobia Likelihood ratio test * **
0.99 0.75 1.01 0.83 1.96
(0.98–0.99)** (0.64–0.89)** (0.91–1.12) (0.69–1.00) (1.50–2.57)**
Lifetime suicide attempts AOR (95% CI) 0.98 0.41 0.80 0.80 2.01
(0.97–0.99)** (0.28–0.62)** (0.68–0.94)** (0.59–1.07) (1.45–2.78)**
1.50 (1.12–2.01)**
1.83 (1.26–2.64)**
0.92 (0.64–1.32) 2.08 (1.41–3.07)**
0.95 (0.62–1.44) 2.19 (1.52–3.15)**
0.97 (0.65–1.44)
1.11 (0.63–1.95)
3.26 (2.72–3.91)** 0.88 (0.50–1.54)
2.80 (1.94–4.05)** 0.80 (0.45–1.43)
1.68 (1.27–2.23)** 1.59 (1.06–2.37)*
1.60 (1.06–2.41)* 1.57 (0.98–2.51)
1.58 (1.24–2.00)**
1.74 (1.26–2.42)**
1.80 (1.37–2.35)**
1.96 (1.37–2.80)**
1.04 (0.80–1.35)
1.04 (0.77–1.40)
v2(16) = 596.88, p < .0001
v2(16) = 351.74, p < .0001
p < 0.05. p < 0.01.
phobia and agoraphobia were no longer significantly associated with suicidal ideation. SAD, GAD and PTSD remained significantly associated with a history of suicide attempts while specific phobia, agoraphobia and PD were no longer associated with attempts. Curiously, bipolar disorder was not a significant predictor of ideation or attempts, a fact likely explained by both high rates of
comorbidity and the low base rate for this condition. Since variables for race/ethnicity were not correlated with suicidal ideation, suicide attempts, or any of the anxiety disorders (with the exception of a very weak association with SAD: r = .035 among Hispanics), these were not included in the analyses presented. Additional analyses showed that their inclusion, however, did not affect the significance or direction of any of the findings. The differential associations between men and women for suicidal ideation and suicide attempts across the different anxiety disorders are presented in Table 4. Given considerations of statistical power, only those predictors thought to be relevant from the previous analyses were included. For men, after controlling for risk factors, PTSD was found to convey a significant risk for suicidal ideation while panic disorder conveyed a significant risk for suicide attempts. These findings related to attempts should be interpreted with caution, however, given the low number of attempts among men (n = 50). Among women, SAD, PD, PTSD, and GAD conveyed significant risk for suicidal ideation while SAD, GAD and PTSD conveyed significant risk for suicide attempts. In order to compare our findings to those of the NCS study by Sareen et al. (2005b), additional multivariate analyses were conducted using the same variables in the overall analysis (see Table 3) and the addition of a variable coded for three or more diagnoses. Our findings were somewhat similar to theirs: PTSD (OR = 1.57, 95% CI = 1.18–2.09, p < .01) and SAD (OR = 1.45, 95% CI = 1.11–1.88, p < .01) were the only anxiety disorders predicting suicidal ideation, and PTSD (OR = 1.67, 95% CI = 1.21–2.31, p < .01) was the only anxiety disorder predicting suicide attempts. This variable was also added to the predictors used in Table 4 for additional analyses by gender, and no changes appeared in the anxiety disorders demonstrated to significantly predict suicidal ideation or attempts among women. Among men, PTSD remained a significant predictor of suicidal ideation (OR = 2.43, 95% CI = 1.40–4.23, p < .01), while no anxiety disorder predicted attempts (again this finding was likely due to low power).
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Table 4 Multivariate logistic regression analysis of suicidal ideation and attempts for men and women. Lifetime suicidal ideation AOR (95% CI)
Age Education Borderline personality disorder Anti-social personality disorder Alcohol abuse or dependence Major depression Social anxiety disorder Panic disorder ± agoraphobia Generalized anxiety disorder Posttraumatic stress disorder Likelihood ratio test * **
Lifetime suicide attempts AOR (95% CI)
Men
Women
Men
Women
0.99 (0.98–1.00) 0.94 (0.79–1.12) 2.13 (1.14–3.98)* 1.53 (1.02–2.30)* 2.46 (1.53–3.95)** 4.04 (2.70–6.04)** 1.33 (0.85–2.09) 1.46 (0.84–2.55) 1.03 (0.53–1.98) 3.08 (1.78–5.31)** v2(10) = 268.25, p < .0001
0.99 (0.98–1.00)** 1.04 (0.92–1.17) 1.95 (1.43–2.66)** 1.52 (1.11–2.07)** 1.62 (1.04–2.54)* 2.95 (2.29–3.81)** 1.86 (1.43–2.42)** 1.55 (1.16–2.08)** 1.84 (1.40–2.43)** 1.54 (1.13–2.10)** v2(10) = 324.92, p < .0001
0.98 (0.96–1.00) 0.97 (0.76–1.24) 3.27 (1.72–6.18)** 1.95 (1.14–3.35)* 2.53 (1.44–3.83)** 3.21 (1.60–5.75)** 0.83 (0.36–1.91) 2.23 (1.09–4.55)* 0.93 (0.39–2.21) 2.01 (0.94–4.32) v2(10) = 112.60, p < .0001
0.98 (0.96–0.99)** 0.72 (0.57–0.90)** 1.68 (1.10–2.57)* 1.96 (1.29–2.96)** 2.19 (1.48–3.24)** 2.77 (1.84–4.18)** 1.96 (1.25–3.05)** 1.25 (0.79–1.96) 2.02 (1.42–2.86)** 1.99 (1.38–2.88)** v2(10) = 223.90, p < .0001
p < 0.05. p < 0.01.
6. Discussion Overall, the findings of the current study suggest that GAD, PTSD, SAD, and PD are uniquely predictive of suicidal ideation. Among all respondents, only GAD, PTSD, and SAD were associated with suicide attempts, findings that run counter to previous studies suggesting a strong relationship between panic disorder and suicide attempts (Weissman et al., 1989). These results were observed after controlling for a range of important covariates, including certain Axis II diagnoses, substance abuse/dependence, and depression. Analyses were further stratified by gender, which revealed important differences in the relationships between anxiety disorders and suicide. First, it appears that, among women, a number of anxiety disorders are predictive of suicidal ideation, including PD, GAD, SAD, and PTSD. Interestingly, PTSD was the only anxiety disorder predictive of suicidal ideation for men. Data on suicide attempts tell a somewhat different story. PD but not PTSD was associated with suicide attempts for men, while PTSD, GAD, and SAD were uniquely predictive of suicide attempts for women. Analysis of suicide attempts for men should be interpreted with caution, however, given the relatively small number of suicide attempt cases among this group (n = 50). Indeed, findings from the regression model for men suggest a likely relationship between PTSD and suicide attempts (OR = 2.01) that was non-significant due to low power. To summarize, these data suggest that a wider range of anxiety disorders are associated with increased suicide risk for women, while only PTSD and PD are associated with increased suicide risk for men. These findings add to the literature on suicide in a number ways. In addition to the gender differences already mentioned, this study was unique in providing nationally representative data using DSM-IV diagnostic criteria to demonstrate that anxiety disorders act as independent risk factors for suicidal behavior. The multivariate analyses also included borderline personality disorder, an important covariate not considered in previous research on this topic. This variable was, indeed, found to be a strong predictor of suicidal ideation and suicide attempts in our own analyses. The findings of the current study were similar to those of the longitudinal study conducted by Sareen et al. (2005a), though they did not include PTSD diagnosis in their analyses and found specific phobia to be a strong predictor of suicidal behavior. They differed in important respects from the cross-sectional study by Sareen and colleagues (2005b), which found PTSD to be the only significant predictor of suicidal ideation and suicide attempts in the NCS. These differences are due in part to the fact that they included a variable coded for three or more diagnoses in their multivariate
test, which likely reduced the significance of some of their predictors. A few limitations of the present study should be noted. Given that the data were cross-sectional and used lifetime histories of disorders and suicidality, caution should be used when interpreting the findings, as they do not necessarily imply causal relationships between anxiety disorders and suicidal behavior. In addition, our analyses examined predictors of suicidal ideation and suicide attempts. This is a common methodology used to evaluate risk factors for suicide, as these variables are established risk factors for completed suicides (Suominen et al., 2004). However, it is possible that the identified risk factors would not predict completed suicide. In addition, the temporal nature of the relationship between anxiety disorders and suicide was not examined, and it is possible that suicidal ideation and suicide attempts occurred prior to disorder onset. Further, the non-significant relationship between agoraphobia and suicidality in multivariate tests may have been due in part to the low number meeting for this diagnosis (n = 99). Lastly, diagnostic information on obsessive-compulsive disorder (OCD) and schizophrenia was not available in the NCS-R. Future research, perhaps using large-scale longitudinal designs, is needed to address these limitations. Research in this area would also benefit from studies examining the mechanisms by which anxiety disorders increase risk for suicide. For example, it is possible that feelings of distrust characteristic of PTSD or social avoidance associated with SAD may lead to a lower sense of belongingness, an important vulnerability factor in interpersonal models of suicide (Joiner, 2005). Suicidal behavior among anxious individuals may also be an attempt to avoid extreme distress that they may be experiencing. The current study carries with it some important implications. First and foremost, it provides further evidence of the consequences of anxiety disorders and the necessity of their early detection and treatment. It also emphasizes the importance of suicide risk assessment in the treatment of individuals with anxiety disorders. Lastly, these data suggest that standard suicide risk assessment may be aided by the evaluation of the presence of certain anxiety disorders identified herein as independent risk factors. Conflict of interest All authors declare that they have no conflicts of interest. Contributors Dr. Cougle designed the study. Dr. Cougle and Ms. Keough undertook the statistical analyses. All authors participated in the
J.R. Cougle et al. / Journal of Psychiatric Research 43 (2009) 825–829
writing and preparation of the manuscript and have approved the final manuscript. Role of Funding Source The authors have no funding sources to declare. Acknowledgments We would like to thank the NCS-R research group for providing us with access to their data. A complete description of the measures used in the NCS-R is available at. References American Psychiatric Association. Diagnostic and statistical manual of mental Disorders. 4th ed.-TR. Washington, DC; 2000. Bolton JM, Cox BJ, Afifi TO, Enns MW, Bienvenu OJ, Sareen MD. Anxiety disorders and risk for suicide attempts: Findings from the Baltimore epidemiological catchment area follow-up study. Depression and Anxiety 2008;25:477–81. Brown TA, Campbell LA, Lehman CL, Grisham JR, Mancill RB. Current and lifetime comorbidity of the DSM-IV anxiety and mood disorders in a large clinical sample. Journal of Abnormal Psychology 2001;110:585–99. Cavanagh JT, Carson AJ, Sharpe M, Lawrie SM. Psychological autopsy studies of suicide: a systematic review. Psychological Medicine 2003;33:395–405. Centers for Disease Control and Prevention. Web-based Injury Statistics Query and Reporting System (WISQARS) [document on the Internet]. National Center for Injury Prevention and Control; 2005 [cited 2008 September 25]. Available from: . First MB, Spitzer RL, Gibbon M, Williams JBW. Structured Clinical Interview for DSM-IV-TR Axis I disorders, research version, non-patient edition (SCID-I/np). New York, New York State Psychiatric Institute; 2002.
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Contents lists available at ScienceDirect
Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/jpsychires
Anxiety disorders and suicidality in the National Comorbidity Survey-Replication Jesse R. Cougle *, Meghan E. Keough, Christina J. Riccardi, Natalie Sachs-Ericsson Department of Psychology, Florida State University, P.O. Box 3064301 Tallahassee, FL 32306, United States
a r t i c l e
i n f o
Article history: Received 22 October 2008 Received in revised form 4 December 2008 Accepted 12 December 2008
Keywords: Anxiety Suicide Depression Risk factors Epidemiology
a b s t r a c t Objective: The current study sought to examine the unique associations between anxiety disorders and suicidality using a large nationally representative sample and controlling for a number of established risk factors for suicide. Method: Data from the National Comorbidity Survey-Replication were used for analyses. Lifetime diagnostic history and demographics were obtained in this survey through a structured interview. Lifetime suicidal ideation and attempts were also assessed. Results: Multivariate analyses covarying for psychiatric comorbidity and demographic variables found social anxiety disorder (SAD), posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), and panic disorder (PD) to be unique predictors of suicidal ideation, while only SAD, PTSD, and GAD were predictive of suicide attempts. Analyses by gender indicated that each of these four disorders were predictive of suicidal ideation or suicide attempts among women, while only PTSD and PD acted as risk factors among men. Conclusions: Findings provide further evidence of the negative impact of anxiety disorders, suggest efforts should be made towards their early detection and treatment, and emphasize the importance of suicide risk assessment in treating individuals with anxiety disorders. Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction In the United States alone, 1.3% of all deaths and more than 32,000 deaths per year are by suicide (Center for Disease Control and Prevention, 2005). Efforts to prevent such deaths are aided by the fact that up to 95% of suicides are committed by people with one or more psychological disorders (Cavanagh et al., 2003). If certain disorders are identified as independent risk factors for suicide, then it is likely that treatment of these may lower suicide risk. Indeed, research has found that treatment of depression and bipolar disorder leads to reductions in completed suicides (Rihmer, 2001; Tondo et al., 2001). The psychiatric problems most consistently linked to suicidality are mood disorders and certain categories of personality disorders (e.g., borderline personality disorder). However, research has also accumulated over the past several years indicating that anxiety disorders confer unique risk of suicide. Panic disorder (PD) is one of the anxiety disorders studied most in relation to suicide, though evidence supporting the relationship has been inconsistent. Weismann and colleagues (Weissman et al., 1989) found a strong association between PD and suicidality using data from the epidemiological catchment area study. However, Hornig and
* Corresponding author. Tel.: +1 850 645 8729; fax: +1 850 644 7739. E-mail address: [email protected] (J.R. Cougle). 0022-3956/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpsychires.2008.12.004
McNally (1995) reanalyzed the same data and found this relationship to disappear after controlling for certain comorbid disorders. Comorbidity is an important consideration when evaluating risk factors for suicidal behavior. Psychological disorders rarely occur alone, and anxiety disorders such as posttraumatic stress disorder (PTSD) more often occur with depression (a strong risk factor for suicidality) than without it (Brown et al., 2001). Multivariate tests that include a range of predictors are, thus, necessary. Sareen and colleagues (2005a,b) and Bolton et al. (2008) recently examined the associations between anxiety disorders and suicide in three different studies. In a longitudinal survey, the presence of any anxiety disorder was found to be associated with significant risk for subsequent suicidal ideation and suicide attempts (Sareen et al., 2005a). Though trends were similar for each anxiety disorder in increasing suicide risk, obsessive-compulsive disorder (OCD), generalized anxiety disorder (GAD), and social anxiety disorder (SAD) appeared to be most prominently associated with subsequent suicidal ideation, while simple phobia was most strongly associated with subsequent suicide attempts. Additional analyses indicated that presence of any anxiety disorder with comorbid mood disorder was associated with greater risk of suicide attempts than mood disorder alone. Some of these analyses, understandably, were limited by low statistical power (i.e., there were only 39 cases of new suicide attempts in the follow-up assessments). In addition, PTSD, one of the more prominent predictors of suicidality, was not assessed in their design. In a second study, using data from the
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cross-sectional National Comorbidity Survey (NCS) (Sareen et al., 2005b), these researchers found lifetime PTSD to be the only anxiety disorder acting as a unique predictor of lifetime suicidal ideation and suicide attempts. More recently, using data from the Baltimore epidemiological catchment area survey, investigators found the presence of one or more anxiety disorders to uniquely predict subsequent suicide attempts, though individual anxiety disorders were collapsed into a single variable for their analysis and PTSD was not assessed in this study (Bolton et al., 2008). All of these studies provide valuable contributions to the suicide literature; however, they are limited in certain ways. First, borderline personality disorder, a strong risk factor for suicidal behavior, was not considered in the analyses. In addition, given that the presence of three or more diagnoses is a potent risk factor for suicide (Kessler et al., 1999), Sareen et al. (2005b) included a variable coded for this in their cross-sectional NCS study. Since most predictors were added into this variable and comorbidity is already being taken into account in the analysis, the inclusion of this variable may have artificially reduced the potency of each predictor. Lastly, diagnoses in these studies were assessed using either DSM-III-R (Sareen et al., 2005a,b) or DSM-III (Bolton et al., 2008) criteria. Since significant changes in diagnostic criteria of disorders such as PTSD had been made in the DSM-IV (American Psychiatric Association, 2000), it is important to update these analyses using current criteria. The current study addressed some of the limitations in extant research on anxiety disorders and suicidality using the National Survey of Comorbidity-Replication (NCS-R). The NCS-R is a more recent nationally representative survey than the NCS that includes data on DSM-IV diagnoses and borderline and anti-social personality disorders. Lifetime history of several different anxiety disorders were tested as predictors of lifetime suicidal ideation and attempts. In addition, given that suicidal behavior differs between men and women (Kessler et al., 1999), we conducted further analyses by gender.
2. Methods 2.1. Sample The NCS-R is composed of a representative sample of Englishspeaking adults from the contiguous United States. Participants were interviewed in-person at their place of residence between February 2001 and April 2003. A detailed description of the methodology, weighting and sampling procedures used in the NCS-R have been provided by Kessler and colleagues (Kessler et al., 2005). All respondents completed Part I of the interview (N = 9282) which contained a section covering each of the core mental health disorders. Part II included sections on disorders of secondary importance as well as risk factors, consequences, services and other correlates of mental health disorders. In an effort to reduce respondent burden, Part II was completed only by those who met criteria for a lifetime core diagnosis as well as a probability subsample of those who did not meet criteria. The current investigation was based on data from both Part I and II from which we obtained a subsample of individuals (N = 4131) who reported on lifetime suicidal ideation and suicide attempts. The sample was 56% female with an average age of 49.88 (SD = 16.3). The racial and ethnic representation of the study participants was 73.2% Caucasian, 12.5% African–American, 10.8% Hispanic, and 3.5% from other ethnicities. 3. Procedure Based on the 2000 US Census, a stratified, multistage probability sample was created. Respondents received a letter describing
the survey and their potential participation several days before in-person contact was made. Interviews were conducted by professional interviewers who had obtained extensive training and were closely supervised by the Institute for Social Research. The administration of the interview was completed face-to-face with the assistance of a laptop computer. The interviewers obtained verbal informed consent from each respondent. The consent procedures were approved by the Human Subject Research Committees at Harvard Medical School and the University of Michigan. Respondents received $50 as a token of appreciation for completing the interview. The overall response rate was 70.9%. Part I was weighted to adjust for discrepancies between the sample and the US Census in terms of geographic and sociodemographic variables. Additional weighting of Part II was conducted to adjust for differential probability of selection from Part I (Kessler et al., 2004). 4. Measures Demographic: The interview included an extensive demographic section that assessed sex, age, education, marital status as well as other demographic variables. Diagnostic Assessment: Lifetime anxiety, mood and substance use disorders were assessed using the World Mental Health Survey Initiative version of the World Health Organization Composite International Diagnostic Interview (WMH-CIDI) reference. This is a structured diagnostic interview from which DSM-IV Axis I (American Psychiatric Association, 2000) diagnoses are derived. The CIDI has been found to have good validity and reliability (First et al., 2002). The Axis II diagnoses of anti-social personality disorder (ASPD) and borderline personality disorder (BPD) were evaluated using their respective screening items from the International Personality Disorder Examination which has been shown to have good sensitivity and specificity (Loranger et al., 1994). Cases of ASPD and BPD were identified by computing participant’s continuous scores on the screening items for each disorder and then applying a cutscore based on established lifetime rates (Robins et al., 1991). Suicidality: Respondents’ lifetime history of suicidal ideation and suicide attempts were assessed during the interview. Respondents who reported they had ever ‘‘seriously thought about committing suicide” were coded as having a history of suicidal ideation. Those who endorsed having ‘‘ever attempted suicide” were coded as having a history of suicide attempts. 5. Results All analyses were conducted using Statistical Analysis Software (SAS) version 9.1 and employed the appropriate NCS-R statistical weights to ensure the sample was representative of the general US population. Table 1 presents the results of the univariate associations between lifetime suicidal ideation and attempts and established demographic and diagnostic risk factors. As expected, suicide attempts were significantly associated with each risk factor while suicidal ideation was significantly associated with each risk factor except education. The second set of univariate comparisons examined suicidal ideation and attempts across the different lifetime anxiety disorders (see Table 2). In uncontrolled analyses, each anxiety disorder conveyed a significant risk for both suicidal ideation and suicide attempts. To further assess the risk conveyed by lifetime anxiety disorders by covarying the established demographic and diagnostic risk factors, both the risk factors and the anxiety disorders were entered into a multivariate logistical regression. Social anxiety disorder (SAD), panic disorder (PD), generalized anxiety disorder (GAD) and posttraumatic stress disorder (PTSD) all remained significantly associated with a history of suicidal ideation (see Table 3). Specific
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J.R. Cougle et al. / Journal of Psychiatric Research 43 (2009) 825–829 Table 1 Associations between demographic data, established risk factors and suicidal ideation and suicide attempts.
Total sample Age Gender (Male) Married/cohabiting Education Borderline personality disorder Anti-social personality disorder Bipolar disorder Major depressive disorder
Suicidal ideation N%
OR (95% CI)
Suicide attempts N%
OR (95% CI)
(557/4131) 14.0% – (213/1826) 11.7% (300/2596) 11.6% – (149/347) 42.9% (157/508) 30.9% (44/87) 50.6% (288/774) 37.2%
– 0.98 0.71 0.59 0.94 5.88 3.41 6.79 6.27
(184/4128) 4.5% – (50/1825) 2.7% (81/2596) 3.1% – (72/344) 20.9% (69/505) 13.7% (22/87) 25.3% (108/770) 14.0%
– 0.97 0.46 0.45 0.74 8.60 4.89 8.30 7.04
(0.97–0.98)** (0.60–0.83)** (0.50–0.70)** (0.86–1.02) (4.78–7.24)** (2.69–4.31)** (5.12–9.01)** (5.42–7.25)**
(0.96–0.98)** (0.34–0.63)** (0.35–0.56)** (0.65–0.84)** (6.65–11.13)** (3.59–6.65)** (5.70–12.09)** (5.12–9.68)**
*
p < 0.05. p < 0.01.
**
Table 2 Prevalence of lifetime suicidal ideation and suicide attempts across anxiety disorders with univariate comparisons.
Total sample Agoraphobia without panic Social anxiety disorder Panic disorder ± agoraphobia Generalized anxiety disorder Posttraumatic stress disorder Specific phobia
Suicidal ideation N%
OR (95% CI)
Suicide attempts N%
OR (95% CI)
(557/4131) 14.0% (45/99) 45.5% (164/471) 34.8% (99/251) 39.4% (136/350) 38.9% (120/298) 40.3% (142/525) 27.0%
– 5.43 4.18 4.62 4.81 4.97 2.70
(184/4128) 4.5% (20/99) 20.2% (67/468) 14.3% (43/249) 17.3% (57/348) 16.4% (56/298) 18.8% (57/524) 10.9%
– 5.85 5.07 5.59 5.59 6.68 3.36
(4.02–7.33)** (3.54–4.95)** (3.63–5.86)** (4.02–5.76)** (4.11–6.00)** (2.16–3.39)**
(4.09–8.37)** (3.71–6.93)** (4.11–7.61)** (4.27–7.34)** (5.11–8.74)** (2.43–4.65)**
*p < 0.05. **
p < 0.01.
Table 3 Multivariate logistic regression analysis of lifetime suicidal ideation and suicide attempts. Lifetime suicidal ideation AOR (95% CI) Age Sex Education Married/cohabiting Borderline personality disorder Anti-social personality disorder Bipolar disorder Alcohol abuse or dependence Drug abuse or dependence Major depression Agoraphobia without panic disorder Social anxiety disorder Panic disorder ± agoraphobia Generalized anxiety disorder Posttraumatic stress disorder Specific phobia Likelihood ratio test * **
0.99 0.75 1.01 0.83 1.96
(0.98–0.99)** (0.64–0.89)** (0.91–1.12) (0.69–1.00) (1.50–2.57)**
Lifetime suicide attempts AOR (95% CI) 0.98 0.41 0.80 0.80 2.01
(0.97–0.99)** (0.28–0.62)** (0.68–0.94)** (0.59–1.07) (1.45–2.78)**
1.50 (1.12–2.01)**
1.83 (1.26–2.64)**
0.92 (0.64–1.32) 2.08 (1.41–3.07)**
0.95 (0.62–1.44) 2.19 (1.52–3.15)**
0.97 (0.65–1.44)
1.11 (0.63–1.95)
3.26 (2.72–3.91)** 0.88 (0.50–1.54)
2.80 (1.94–4.05)** 0.80 (0.45–1.43)
1.68 (1.27–2.23)** 1.59 (1.06–2.37)*
1.60 (1.06–2.41)* 1.57 (0.98–2.51)
1.58 (1.24–2.00)**
1.74 (1.26–2.42)**
1.80 (1.37–2.35)**
1.96 (1.37–2.80)**
1.04 (0.80–1.35)
1.04 (0.77–1.40)
v2(16) = 596.88, p < .0001
v2(16) = 351.74, p < .0001
p < 0.05. p < 0.01.
phobia and agoraphobia were no longer significantly associated with suicidal ideation. SAD, GAD and PTSD remained significantly associated with a history of suicide attempts while specific phobia, agoraphobia and PD were no longer associated with attempts. Curiously, bipolar disorder was not a significant predictor of ideation or attempts, a fact likely explained by both high rates of
comorbidity and the low base rate for this condition. Since variables for race/ethnicity were not correlated with suicidal ideation, suicide attempts, or any of the anxiety disorders (with the exception of a very weak association with SAD: r = .035 among Hispanics), these were not included in the analyses presented. Additional analyses showed that their inclusion, however, did not affect the significance or direction of any of the findings. The differential associations between men and women for suicidal ideation and suicide attempts across the different anxiety disorders are presented in Table 4. Given considerations of statistical power, only those predictors thought to be relevant from the previous analyses were included. For men, after controlling for risk factors, PTSD was found to convey a significant risk for suicidal ideation while panic disorder conveyed a significant risk for suicide attempts. These findings related to attempts should be interpreted with caution, however, given the low number of attempts among men (n = 50). Among women, SAD, PD, PTSD, and GAD conveyed significant risk for suicidal ideation while SAD, GAD and PTSD conveyed significant risk for suicide attempts. In order to compare our findings to those of the NCS study by Sareen et al. (2005b), additional multivariate analyses were conducted using the same variables in the overall analysis (see Table 3) and the addition of a variable coded for three or more diagnoses. Our findings were somewhat similar to theirs: PTSD (OR = 1.57, 95% CI = 1.18–2.09, p < .01) and SAD (OR = 1.45, 95% CI = 1.11–1.88, p < .01) were the only anxiety disorders predicting suicidal ideation, and PTSD (OR = 1.67, 95% CI = 1.21–2.31, p < .01) was the only anxiety disorder predicting suicide attempts. This variable was also added to the predictors used in Table 4 for additional analyses by gender, and no changes appeared in the anxiety disorders demonstrated to significantly predict suicidal ideation or attempts among women. Among men, PTSD remained a significant predictor of suicidal ideation (OR = 2.43, 95% CI = 1.40–4.23, p < .01), while no anxiety disorder predicted attempts (again this finding was likely due to low power).
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Table 4 Multivariate logistic regression analysis of suicidal ideation and attempts for men and women. Lifetime suicidal ideation AOR (95% CI)
Age Education Borderline personality disorder Anti-social personality disorder Alcohol abuse or dependence Major depression Social anxiety disorder Panic disorder ± agoraphobia Generalized anxiety disorder Posttraumatic stress disorder Likelihood ratio test * **
Lifetime suicide attempts AOR (95% CI)
Men
Women
Men
Women
0.99 (0.98–1.00) 0.94 (0.79–1.12) 2.13 (1.14–3.98)* 1.53 (1.02–2.30)* 2.46 (1.53–3.95)** 4.04 (2.70–6.04)** 1.33 (0.85–2.09) 1.46 (0.84–2.55) 1.03 (0.53–1.98) 3.08 (1.78–5.31)** v2(10) = 268.25, p < .0001
0.99 (0.98–1.00)** 1.04 (0.92–1.17) 1.95 (1.43–2.66)** 1.52 (1.11–2.07)** 1.62 (1.04–2.54)* 2.95 (2.29–3.81)** 1.86 (1.43–2.42)** 1.55 (1.16–2.08)** 1.84 (1.40–2.43)** 1.54 (1.13–2.10)** v2(10) = 324.92, p < .0001
0.98 (0.96–1.00) 0.97 (0.76–1.24) 3.27 (1.72–6.18)** 1.95 (1.14–3.35)* 2.53 (1.44–3.83)** 3.21 (1.60–5.75)** 0.83 (0.36–1.91) 2.23 (1.09–4.55)* 0.93 (0.39–2.21) 2.01 (0.94–4.32) v2(10) = 112.60, p < .0001
0.98 (0.96–0.99)** 0.72 (0.57–0.90)** 1.68 (1.10–2.57)* 1.96 (1.29–2.96)** 2.19 (1.48–3.24)** 2.77 (1.84–4.18)** 1.96 (1.25–3.05)** 1.25 (0.79–1.96) 2.02 (1.42–2.86)** 1.99 (1.38–2.88)** v2(10) = 223.90, p < .0001
p < 0.05. p < 0.01.
6. Discussion Overall, the findings of the current study suggest that GAD, PTSD, SAD, and PD are uniquely predictive of suicidal ideation. Among all respondents, only GAD, PTSD, and SAD were associated with suicide attempts, findings that run counter to previous studies suggesting a strong relationship between panic disorder and suicide attempts (Weissman et al., 1989). These results were observed after controlling for a range of important covariates, including certain Axis II diagnoses, substance abuse/dependence, and depression. Analyses were further stratified by gender, which revealed important differences in the relationships between anxiety disorders and suicide. First, it appears that, among women, a number of anxiety disorders are predictive of suicidal ideation, including PD, GAD, SAD, and PTSD. Interestingly, PTSD was the only anxiety disorder predictive of suicidal ideation for men. Data on suicide attempts tell a somewhat different story. PD but not PTSD was associated with suicide attempts for men, while PTSD, GAD, and SAD were uniquely predictive of suicide attempts for women. Analysis of suicide attempts for men should be interpreted with caution, however, given the relatively small number of suicide attempt cases among this group (n = 50). Indeed, findings from the regression model for men suggest a likely relationship between PTSD and suicide attempts (OR = 2.01) that was non-significant due to low power. To summarize, these data suggest that a wider range of anxiety disorders are associated with increased suicide risk for women, while only PTSD and PD are associated with increased suicide risk for men. These findings add to the literature on suicide in a number ways. In addition to the gender differences already mentioned, this study was unique in providing nationally representative data using DSM-IV diagnostic criteria to demonstrate that anxiety disorders act as independent risk factors for suicidal behavior. The multivariate analyses also included borderline personality disorder, an important covariate not considered in previous research on this topic. This variable was, indeed, found to be a strong predictor of suicidal ideation and suicide attempts in our own analyses. The findings of the current study were similar to those of the longitudinal study conducted by Sareen et al. (2005a), though they did not include PTSD diagnosis in their analyses and found specific phobia to be a strong predictor of suicidal behavior. They differed in important respects from the cross-sectional study by Sareen and colleagues (2005b), which found PTSD to be the only significant predictor of suicidal ideation and suicide attempts in the NCS. These differences are due in part to the fact that they included a variable coded for three or more diagnoses in their multivariate
test, which likely reduced the significance of some of their predictors. A few limitations of the present study should be noted. Given that the data were cross-sectional and used lifetime histories of disorders and suicidality, caution should be used when interpreting the findings, as they do not necessarily imply causal relationships between anxiety disorders and suicidal behavior. In addition, our analyses examined predictors of suicidal ideation and suicide attempts. This is a common methodology used to evaluate risk factors for suicide, as these variables are established risk factors for completed suicides (Suominen et al., 2004). However, it is possible that the identified risk factors would not predict completed suicide. In addition, the temporal nature of the relationship between anxiety disorders and suicide was not examined, and it is possible that suicidal ideation and suicide attempts occurred prior to disorder onset. Further, the non-significant relationship between agoraphobia and suicidality in multivariate tests may have been due in part to the low number meeting for this diagnosis (n = 99). Lastly, diagnostic information on obsessive-compulsive disorder (OCD) and schizophrenia was not available in the NCS-R. Future research, perhaps using large-scale longitudinal designs, is needed to address these limitations. Research in this area would also benefit from studies examining the mechanisms by which anxiety disorders increase risk for suicide. For example, it is possible that feelings of distrust characteristic of PTSD or social avoidance associated with SAD may lead to a lower sense of belongingness, an important vulnerability factor in interpersonal models of suicide (Joiner, 2005). Suicidal behavior among anxious individuals may also be an attempt to avoid extreme distress that they may be experiencing. The current study carries with it some important implications. First and foremost, it provides further evidence of the consequences of anxiety disorders and the necessity of their early detection and treatment. It also emphasizes the importance of suicide risk assessment in the treatment of individuals with anxiety disorders. Lastly, these data suggest that standard suicide risk assessment may be aided by the evaluation of the presence of certain anxiety disorders identified herein as independent risk factors. Conflict of interest All authors declare that they have no conflicts of interest. Contributors Dr. Cougle designed the study. Dr. Cougle and Ms. Keough undertook the statistical analyses. All authors participated in the
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writing and preparation of the manuscript and have approved the final manuscript. Role of Funding Source The authors have no funding sources to declare. Acknowledgments We would like to thank the NCS-R research group for providing us with access to their data. A complete description of the measures used in the NCS-R is available at
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