Nonsuicidal self-injury as a time-invariant predictor of adolescent suicide ideation and attempts in a diverse community sample.

Self-injurious thoughts and behaviors are remarkably dangerous, yet relatively understudied phenomena (Prinstein, 2008). In particular, relatively few longitudinal data are available to understand prospective predictors of self-injury. Moreover, research studies rarely discretely identify and examine associations among the multiple types of self-injurious thoughts and behaviors that have been identified in the literature (e.g., nonsuicidal self-injury, suicide ideation, threats, gestures, attempts, etc.; Nock & Kessler, 2006; Silverman, Berman, Sanddal, O’Carroll, & Joiner, 2007). Consequently, relatively little is known regarding the predictors of self-injury beyond broad, distal factors (e.g., depressive symptoms, prior self-injury, substance use), particularly in adolescence (Nock, 2009; Prinstein, 2008). However, a substantial body of research recently has emerged on at least one form of self-injury: nonsuicidal self-injury (NSSI). Defined as behavior that is direct, deliberate, and not socially sanctioned, NSSI causes damage to one’s body tissue and is enacted without the intent to die (Nock, 2010). NSSI is remarkably prevalent, especially among adolescents. Lifetime prevalence rates in community samples range from 15.9 to 21.2% (e.g., Muehlenkamp & Gutierrez, 2004; Ross & Heath, 2002). Studies of NSSI have proliferated and gained added clinical importance for at least three reasons. First, NSSI is a proposed diagnostic category in the draft DSM-V (Selby, Bender, Gordon, Nock, & Joiner, 2011). Second, NSSI is associated concurrently with suicidal thoughts and behaviors (Andover & Gibb, 2010; Klonsky & Olino, 2008; Lloyd-Richardson, Perrine, Dierker, & Kelley, 2007; Nock, Joiner, Gordon, Lloyd-Richardson, & Prinstein, 2006). Third, recent theories suggest that NSSI may be a risk factor for later suicidal thoughts and behaviors (Brent, 2011; Joiner, 2005). The latter hypothesis infrequently has been examined, however. The present study examines NSSI as a long-term, time-invariant longitudinal risk factor for suicide ideation, threats or gestures, and attempts during an adolescent transition period associated with increased risk for suicidality. Epidemiological data suggest that suicide ideation is remarkably prevalent during the high-school aged adolescent period (13.8%; CDC, 2010). The prevalence of suicide attempts is also quite high (6.3%; CDC, 2010). Between the age groups of 10–14 to 15–19, the rate of completed suicide increases almost sevenfold (from 1.1 to 7.4 per 100,000; CDC, 2008). In addition, suicide is the third leading cause of death for children and adolescents aged 10–19 years (CDC, 2008). Less is known about the prevalence of suicide threats or gestures, sometimes defined as “self-injury in which there is no intent to die, but instead an intent to give the appearance of a suicide attempt in order to communicate with others” (Nock & Kessler, 2006, p. 616), or as “any interpersonal action, verbal or non-verbal, without a direct self-injurious component, that a reasonable person would interpret as communicating or suggesting that suicidal behavior might occur in the near future” (Silverman et al., 2007, p. 268). Self-injurious behaviors such as threats or gestures and uncompleted suicide attempts are crucial outcomes for investigation, as they place an enormous burden on emergency health care systems, cause significant distress among family and friends, and are the strongest predictors of eventual suicide (Cvinar, 2005; Joiner et al., 2005; Olfson, Gameroff, Marcus, Greenberg, & Shaffer, 2005). Recent theoretical and empirical work suggests that NSSI may be associated with increased suicidal capability (Franklin, Hessel, & Prinstein, 2011; Joiner, 2005). Joiner (2005) suggests that repeated episodes of painful and provocative experiences, such as cutting or burning, may habituate those who engage in NSSI to higher levels of pain. This habituation, or “acquired capability for suicide,” may act as a vulnerability that, when combined with desire for suicide, has been found to significantly predict suicidal behaviors, including attempts and completed suicides (Anestis & Joiner, 2011; Joiner et al., 2009; Nademin et al., 2008; Van Orden, Witte, Gordon, Bender, & Joiner, 2008). Preliminary empirical findings offer some initial support for NSSI as a concurrent correlate of suicidal thoughts and behavior. Higher frequencies of NSSI concurrently are associated with higher levels of suicide ideation and a history of suicide attempts (Andover & Gibb, 2010; Klonsky & Olino, 2008; Lloyd-Richardson et al., 2007; Nock et al., 2006). Few studies have examined the longitudinal association among various forms of self-injury (e.g., Asarnow et al., 2011; Cooper et al., 2005; Owens, Horrocks, House, 2002; Wilkinson, Kelvin, Roberts, Dubicka & Goodyer, 2011). In some cases different forms of self-injury (i.e., suicidal vs. nonsuicidal) have not been explicitly differentiated. For example, Cooper and colleagues (2005) revealed a prospective relationship between any self-harm episode resulting in a hospitalization (including NSSI or suicidal self-injury) and later completed suicide. Similarly, Owens and colleagues (2002) reviewed multiple studies examining the relationship between various forms of self-harm and later non-fatal or fatal self-harm; findings suggested elevated risk for suicide among self-harm patients as compared to the general population. Some short-term longitudinal data examining associations specifically between NSSI and suicidal thoughts or behaviors in clinically-referred populations also have been reported recently. For example, NSSI has been associated with slower decreases in suicide ideation in the nine months following hospital discharge (Prinstein et al., 2008). Asarnow and colleagues (2011) and Wilkinson and colleagues (2011) revealed NSSI frequencies to be a stronger predictors of suicide attempts than were previous suicide attempts over a 24- and 28-week period, respectively. This study aimed to offer at least five unique contributions to the literature examining putative risk associated with NSSI. First, this study used a definition of NSSI consistent with contemporary theory; thus, it was possible to examine NSSI (specifically without suicidal intent) as a predictor of suicidal thoughts and behaviors. Second, this study focused on a diverse community sample, offering findings that are most relevant for prevention efforts. Third, this study was designed to examine the long-term longitudinal prediction of suicidal thoughts and behaviors from NSSI. A two and a half year longitudinal interval was used to examine hypotheses. Fourth, multiple outcomes reflecting discrete suicidal thoughts and behaviors (i.e., suicide ideation, threats or gestures, and attempts) are examined. Last, and perhaps most importantly, this study examines NSSI as a predictor of suicidal thoughts and behaviors while controlling for depressive symptoms and related suicidality as competing predictors. This stringent examination offers a robust test of NSSI as a predictor of later suicidal thoughts and behaviors. It was hypothesized that NSSI would be associated with a higher likelihood of suicidal thoughts over time. Although prior longitudinal research on the developmental course of suicidal ideation is rare, empirical data suggest that ideation may occur episodically, perhaps in conjunction with major depressive episodes (Prinstein et al., 2008; Williams, Crane, Barnhofer, Van der Does, & Segal, 2006). A primary aim of this study was to examine NSSI as a longitudinal predictor of clinically-significant levels of suicide ideation. Thus, data were coded to reflect severe levels of suicide ideation, and an analytic approach allowing for the examination of repeated occurrences nested within individuals was employed. It also was hypothesized that NSSI would be associated with higher occurrences of suicide threats or gestures and suicide attempts over time. Past research has suggested adolescent girls and Latino Americans are more likely than adolescent boys and non-Latino Americans to report suicide ideation, attempts, and depressive symptoms (CDC, 2010). However, there are few extant theories suggesting that the magnitude of the association between NSSI and suicidal thoughts and behaviors may vary with respect to gender or ethnicity. Therefore, each of these demographic variables was explored as a moderator of hypothesized associations for descriptive purposes.