Abstract
Objective: To investigate the usefulness of electrical startle responses and thyroid function as supplements to self-report measures of posttraumatic stress disorder (PTSD).
Method: Invitations were sent to all New Zealand Vietnam War veterans known to be living in North Canterbury; 50 responded and the 35 living in or near Christchurch were included. Self-report measures of PTSD (the Davidson Trauma Scale (DTS) and the Symptom Check List (SCL-90-R)), an eye blink electrical startle response and thyroid function were measured. The DTS was re-administered one to two weeks later to assess short-term test–retest reliability. Six months later the DTS and the electrical startle response were measured again.
Results: The veterans reported a wide range of PTSD severity, with 15/35 reporting prior diagnosis of PTSD. The DTS showed high short-term test–retest reliability (r = 0.93) and a moderate correlation after 6 months (r = 0.73). It also showed sensitivity to change; in one to two weeks the scores increased by nearly half a standard deviation, possibly because of an imminent ‘homecoming’ march. The DTS and a PTSD scale from the SCL-90-R were highly correlated (r = 0.89). The total triiodothyronine (T3) to free thyroxine (T4) ratio measure of thyroid function correlated poorly with self-report (r ≤ 0.27). The electrical startle response also correlated poorly with self-report (r ≤ 0.26), showed low internal consistency between left and right sides (r = 0.43), and correlated 0.39 over six months. It was disliked by the veterans and had increased slightly at 6 month follow-up, perhaps because of sensitization.
Conclusions: The DTS was reliable and correlated highly with the SCL-90-R PTSD scale. Neither thyroid function nor eye blink electrical startle correlated with each other or with selfreport, and reliability was not good for electrical startle. These two measures do not appear to add anything useful to the assessment of PTSD.