Psychological Services (Oct 18, 2018). DOI:10.1037/ser0000309 Program evaluation data from 451 veterans treated with at least four sessions of prolonged exposure (PE) within a U.S. Department of Veterans Affairs outpatient posttraumatic stress disorder program were examined to explore to what degree change by Session 8 predicted achieving meaningful change (MC; 50% reduction on the Posttraumatic Stress Disorder Symptom Scale–Self-Report [PSS-SR]) after Session 8.. To read the full article, log in using your NHS OpenAthens details.