Tonic and Phasic Heart Rate as Predictors of Posttraumatic Stress Disorder

Address correspondence and reprint requests to: Meaghan L. O'Donnell, PhD, E-mail: mod{at}unimelb.edu.au.

	Abstract

Objective: To examine the relationship between acute measures of a) heart rate (HR) immediately after traumatic injury, b) tonic (resting) HR at 1 week post injury, c) phasic (aroused) HR at 1 week post injury, and d) somatic symptoms of arousal in the prediction of subsequent posttraumatic stress disorder (PTSD). Fear conditioning models propose that HR reactivity shortly after trauma may predict PTSD. Method: In a longitudinal study, consecutive injury survivors (n = 197) admitted to a hospital trauma service were assessed within 1 week and at 12 months post injury. HR was assessed by paramedics at the site of the trauma and pulse oximetry technology at 1 week post trauma. Somatic symptoms of arousal were measured using the somatic scale on the Beck Anxiety Inventory (BAI). PTSD was assessed using the Clinician Administered PTSD Scale at 12 months. Results: At 12 months post injury, PTSD was diagnosed in 10% of participants. Only HR change scores (phasic - tonic HR) and BAI scores significantly predicted later PTSD. Conclusions: These findings question the clinical usefulness of tonic HR as a biological marker of later PTSD. The finding that HR reactivity (phasic - tonic) predicts later PTSD has theoretical importance. The strongest predictor of later PTSD was somatic arousal.

Key Words: posttraumatic stress disorder, heart rate, psychophysical arousal, fear conditioning