Do Acute Benefits of Interpersonal Psychotherapy for Posttraumatic Stress Disorder Endure?

The Psychotherapies for Chronic PTSD randomised trial found that three 14-week psychotherapies acutely benefitted patients with chronic posttraumatic stress disorder (PTSD). Previous research has reported sustained follow-up benefits for prolonged exposure (PE) and relaxation therapy (RT), but few comparable data exist for interpersonal psychotherapy (IPT). We describe 3-month follow-up for acute responders to all 3 treatments.

Acute responders, defined a priori as ≥30% improved from baseline, were reevaluated after 3-month no-treatment follow-up by independent evaluators using the Clinician-Administered PTSD Scale (CAPS).

Fifty of 110 initial study entrants met acute responder status at week 14. Forty-three (86%) responders entered follow-up: 23 remitters (CAPS ≤20) and 20 responders. At week 26, 27 had achieved remission status, 10 remained responders, and 6 had relapsed. Of week 14 remitters, 8 of 9 PE, all 8 IPT, and 4 of 6 RT patients remained remitted. Relapse rates were 7% (1/9) for PE, 10% (2/20) for IPT, and 33% (3/9) for RT. At week 26, PE showed greater improvement on CAPS than RT ( P = 0.048) and a trend for superiority over IPT ( P = 0.098), with no significant difference between IPT and RT. Depressive symptoms remained low during follow-up.

These are the first systematic data on follow-up responder status and persistence of acute treatment benefits in patients receiving individual IPT for chronic PTSD. Patients generally maintained gains across treatments, fluctuating most in RT. Study limitations include small sample size and brief follow-up interval. PTSD research should employ response and remission criteria.