Survival of childhood cancer has greatly improved over the past 30 years. However, the decrease in mortality was at the price of increased intensity of treatment, with associated toxicity and resulting morbidity. Many of the treatments were invasive and painful, such as bone marrow biopsies. Repeated hospitalizations separated young children from their parents and all that was familiar. Some of the children and parents experienced the cancer diagnosis and treatment as emotionally traumatic, with responses of horror, intense fear, and/or helplessness and have developed symptoms of Posttraumatic Stress Disorder (PTSD) (1–11).
Response to life-threatening medical illness was included as a potential precipitator for PTSD in the fourth edition of the Diagnostic and Statistical Manual (DSM-IV) of the American Psychiatric Association (DSM IV)(12), Since then there have been many studies of the epidemiology of posttraumatic stress responses to childhood cancer (e.g. 3–12), including comparisons of relative risk for PTSD between childhood cancer survivors and their siblings(10). Although most have used a similar conceptualization of posttraumatic stress, variable definitions of PTSD have been employed across studies. Some studies have focused on the number of stress symptoms present (yes/no for each symptom) while others have used symptom severity or frequency (usually based on a Likert scale ranging from 0 to 3 points) (1–2). Studies utilizing gradient measurements permit analyses of factors that contribute to incremental increases of patients' symptoms, whereas studies utilizing dichotomous variables distinguish those whose scores suggest a psychiatric disorder from those whose do not.
Other studies have used the formal diagnostic criteria set by the DSM IV(1), which requires three symptoms of avoidance behavior, two symptoms of increased arousal, and one symptom of re-experiencing the traumatic event, reported more than 30 days after the trauma (3, 8, 10). However, most studies have not included the additional diagnostic requirement of the DSM IV that the symptoms must be severe enough to cause clinically significant distress or functional impairment (10). Some of the studies have created a sub-clinical threshold for a dichotomous variable termed Posttraumatic Stress Symptoms (PTSS), defined as meeting criteria for 2 but not all 3 sets of symptoms (5–9). This variability in definition has made it impossible to compare across studies. It is unlikely that the same predictors of PTSD (e.g. demographic, cancer or treatment characteristics) or the impact of PTSD on later function will result across studies without common criteriain defining PTSD in clinical studies of childhood cancer survivors.
With work currently underway on a fifth edition of the DSM, it is an opportune time to examine the utility of each of the current criteria for Posttraumatic Stress Disorder (PTSD) as applied to cancer survivors. This paper uses data from a large, multi-site epidemiologic study of adult survivors of childhood cancer and their siblings to address the following objectives:
- To examine the prevalence of PTSD in childhood cancer survivors and siblings using different operational definitions of PTSD
- To examine the associations between these different operational definitions of PTSD and commonly examined demographic and medical variables
- To determine the relative predictive ability of the total number of posttraumatic stress symptoms and the severity oftotal symptoms in the prediction of functional impairment and/or clinically significant distress of childhood cancer survivors