Objective: To examine the implications of use of differential thresholds for studying medical Posttraumatic Stress Disorder (PTSD).
Methods: Self-report data from 6,542 young adult survivors of childhood cancer and 374 of their siblings were used to create clearly differentially defined groups to compare prevalence, correlations and predictors of posttraumatic stress.
Results: Prevalence of posttraumatic stress in survivors compared to siblings differed by definition used, ranging from an odds ratio of 4.21 (95% CI 2.11-8.38) when posttraumatic stress was defined as meeting full symptoms plus functional impairment to 1.42 (95% CI 0.79-2.56) for partial symptoms with functional impairment. Re-experiencing symptoms did not substantially contribute to the ability to identify functional impairment and emotional distress. Although most of the variables associated with posttraumatic stress symptoms and impairment were consistent across definitions of PTSD, marital status and employment demonstrated nonproportional relationships.
Conclusions: Choice of the definition used in studying posttraumatic stress after serious illness alters not only epidemiological findings, but also associations with correlates and predictors. This is important in the current debate about the criteria for PTSD in the upcoming DSMV. Further study is needed to determine if these findings are applicable to people exposed to other types of traumatic events.
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