Comorbidity, impairment, and suicidality in subthreshold PTSD

Reliance on the categorical model of psychiatric disorders has led to neglected study of posttraumatic sequelae that fall short of full criteria for posttraumatic stress disorder (PTSD). Substantial disability and suicidal risk is associated with subthreshold PTSD, but this association has not been well studied. In addition, no studies have examined the role of comorbidity in explaining disability and impairment in subthreshold PTSD.

On National Anxiety Disorders Screening Day 1997, 2,608 out of 9,358 individuals screened for affective and anxiety disorders at 1,521 sites across the United States reported at least one PTSD symptom of at least 1 month's duration. Impairment, comorbid anxiety disorders, major depressive disorder, and rates of suicidality were determined and compared for individuals with no, one, two, three, or four (full PTSD) symptoms on a screening questionnaire. Regression analyses examined the relative contribution of subthreshold PTSD and comorbid disorders to impairment and suicidal ideation.

Impairment, number of comorbid disorders, rates of comorbid major depressive disorder, and current suicidal ideation increased linearly and significantly with each increasing number of subthreshold PTSD symptoms. Individuals with subthreshold PTSD were at greater risk for suicidal ideation even after the authors controlled for the presence of comorbid major depressive disorder.

Higher numbers of subthreshold PTSD symptoms were associated with greater impairment, comorbidity, and suicidal ideation. Disability and impairment found in previous studies of subthreshold PTSD symptoms may be related in part to the presence of comorbid disorders. However, the presence of subthreshold PTSD symptoms significantly raised the risk for suicidal ideation even after the authors controlled for major depressive disorder. Given the broad public health implications of these findings, more efforts are needed to identify subthreshold PTSD symptoms in clinical populations, epidemiologic surveys, and treatment studies.