Pretreatment attrition in a PTSD comparative treatment outcome study


Treatment attrition represents a considerable problem for effective delivery of care for PTSD. While treatment attrition during the course of treatment is well researched, little is known about the factors that affect sample selection before the beginning of a study. Previous research on other Axis I disorders indicates that patients may refuse participation more often because of study medication than because of psychosocial treatment. The present study examines traits and predictors of pretreatment attrition from a study of PTSD that compared treatment outcomes for fluoxetine versus EMDR. Potential study participants were screened over the telephone for study eligibility. During the telephone screen, a total of 394 people met study eligibility requirements but declined participation (59% of total eligible participants). While a variety of factors were cited for declining study participation, consistent with previous research, refusal of study medication emerged as the pre-dominant reason for pretreatment attrition (49%). Results are discussed in terms of how treatment preferences and other pretreatment attrition factors may impact the external validity of comparative treatment outcome studies. Clinical implications discussed include the potential for pretreatment attrition factors to interfere with trauma survivors’ ability to seek and obtain effective treatment






A. Alley
Joseph Spinazzola
Margarter Blaustein
Bessel A. van der Kolk

Original Work Citation

Alley, A., Spinazzola, J., Blaustein, M., & van der Kolk, B. A. (2005, November). Pretreatment attrition in a PTSD comparative treatment outcome study. Poster presented at the the International Society for Traumatic Stress Studies 21st Annual Meeting, Toronto, ON



“Pretreatment attrition in a PTSD comparative treatment outcome study,” Francine Shapiro Library, accessed November 30, 2020,

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