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Posttraumatic stress disorder: do electrical startle responses and thyroid function usefully supplement self-report?
J Elisabeth Wells1, Timothy H Williams, Alastair D Macleod
1Department of Public Health and General Practice, Christchurch School of Medicine and Health Sciences, PO Box 4345, Christchurch, New Zealand. elisabeth.wells@chmeds.ac.nz
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 < or = 0.27). The electrical startle response also correlated poorly with self-report (r < or = 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 self-report, and reliability was not good for electrical startle. These two measures do not appear to add anything useful to the assessment of PTSD.