Evaluation of Veterans’ Suicide Risk With the Use of Linguistic Detection Methods

In 2010, suicide was the tenth leading cause of death in the United States and among the top four leading causes of death for Americans between ages ten and 54 (1). Recent use of the health care system by those who die from suicide has long been seen as an opportunity for intervention (2). However, in the context of clinical care, suicide continues to be difficult both to predict and to prevent (3). Despite efforts to screen and monitor for suicide risk as well as to boost awareness, education about risk factors, and outreach initiatives, suicide remains a significant public health problem (4,5).

Clinical identification of patients who later die from suicide has long been limited by the low base rate and high false-positive rate inherent in the use of any single predictor or even combinations of recognized risk factors (6,7). This limitation has spurred the development of quantitative models for suicide prediction, including both multivariate and nonlinear modeling of structured data elements from questionnaires, rating scales, and demographic factors (8,9). However, limiting analyses to known risk factors may occur at the cost of foregoing untapped valuable information in the written record of the clinical encounter.

Even with direct questioning, patients may not disclose suicidal intent (10–12). Recent qualitative work indicates that patients may see disclosure of suicidal thoughts as shameful and private and feel that such disclosures could expose them to risks of receiving unwanted treatment (13). Consistent with prior research indicating patients’ desire to have a nuanced discussion around suicide attempts (14), patients found the use of questionnaires about suicide risk “perfunctory and disrespectful.” Therefore, building a suicide risk prediction model reliant on direct inquires of and mentions about suicide may not be a rational strategy. Linguistic analysis seeks to tap into another potential source of knowledge. It attempts to glean knowledge regarding suicide risk not from overt keywords related to suicide (for example, “suicide,” “despair,” “gun,” or “agitation”) but rather from more subtle changes in language that may indicate clinicians’ feelings about their patients (15).

Linguistic analysis has been previously applied to documents written by people who later died by suicide. Investigators found that suicidal individuals’ writing in diaries, correspondence, suicide notes, and online venues has unique semantic characteristics, including unique patterns of pronoun use (16,17). Such research has expanded to emerging social environments, such as publicly accessible, open, forum-type online support groups (18,19). Notably, Won and colleagues (20) developed a model for predicting suicide rates in South Korea by using two social constructs developed from text in Weblog entries in social media: suicide-related text and dysphoria-related text.

There has been no prior research using linguistic analysis of notes written by clinicians about patients who later die from suicide. One area of potential interest is measuring the emotional distance between patient and clinician. The concept of emotional distancing was initially described in Schopenhauer’s (21) “Hedgehog’s Dilemma,” which Freud (22) later incorporated into a description of how individuals relate to others in society. Human intimacy can be limited by the potential for emotional harm that can occur in relationships. This results in cautious interpersonal behavior and emotional distance. Prior research using clinician self-report addresses the function of emotional distancing in minimizing and mitigating stress when working with patients who have mental health problems. Van Sant and Patterson (23) found that nurses working with patients in mental health crises used emotional distancing as a protective maneuver; the investigators also described emotional damage to caregivers who did not use such protective maneuvers to establish patient-caregiver boundaries. Kintzle and colleagues (24) explored rates of secondary traumatic stress in a sample of 70 military primary and mental health care providers, who commonly felt “emotionally numb” as a result of serving this population. Thus, in our context, emotional distancing can be conceptualized as a largely unconscious effort that clinicians use to spare themselves from the emotional trauma associated with the suicide of one of their patients.

The advent of computational linguistics has led to approaches of measuring emotional content, including distancing, through analysis of text. Linguistic studies typically measure distancing language by assessing pronoun use and referencing. Frequent use of first-person and second-person pronouns signifies interpersonal closeness, whereas frequent use of the third-person pronouns characterizes interpersonal distance (25,26). “Referencing” describes a situation where a clinician assigns the source of the content of the note to someone other than the clinician him- or herself. Examples of referencing are when a clinician quotes a patient or an authority such as a mental health consultant, cites protocol or guidelines, or otherwise restates comments made by another person involved with the patient’s care. Van De Mieroop (27) found that use of the “quotative” (attributing a communication’s content to a third party) increased when bad news was communicated between doctor and patient.

Our research is conceptually driven by prior research on emotional distancing by mental health providers, which we quantify by measuring the use of distancing language in text written by clinicians. We focus specifically on measures of distancing language that might be used, consciously or not, by clinicians encountering patients at high risk of suicide. We had two hypotheses. Our primary hypothesis was that there would be more distancing language in notes documenting clinical encounters with patients who died from suicide than in notes documenting clinical encounters with patients who remained alive. For our primary hypothesis, we theorized that differences could be observed at least three months prior to the suicide. Our exploratory hypothesis attempted to triangulate the possible finding of increased use of distancing language. For this hypothesis we examined trends in word use in the year preceding suicide. We hypothesized that words related to distancing language would emerge as keywords as the suicide date drew closer.