According to DSM-IV, life-threatening diseases like cancer can trigger a posttraumatic stress disorder (PTSD). Usual diagnostic instruments such as the Impact-of-Event Scale (IES-R) lack in validity. Methods: A cancer-specific theory-based PTSD concept was developed and measured by IES-R items and newly formulated items. 400 rehabilitation patients with heterogeneous tumor diagnoses, which had been diagnosed within the past year, were examined. Using CFA, a screening instrument was developed: the Questionnaire on Cancer-Specific Posttraumatic Stress (PTB-KS). The questionnaire was tested for reliability and construct validity. Results: The statistical analyses revealed that the theoretical model fit the data well (χ2/df = 2.28; CFI = .960; RMSEA = .057). On four scales the PTB-KS encompasses intrusions and avoidance (IES-R), cancer-specific strain and maladjustment. Reliability and convergent validity are satisfactory; discriminant validity has not been demonstrated sufficiently. Discussion: The revised diagnostic model improves the assessment of posttraumatic stress in cancer patients. From a clinical point of view, the PTB-KS is a suitable screening instrument despite methodological limitations.
Available at: http://works.bepress.com/christian-geiser/34/