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Prevalence of Illness-Induced Posttraumatic Stress Disorder in the United States.

There is growing interest in posttraumatic stress disorder (PTSD) in relation to illness, and a recent study by Ahmadi and colleagues in the April 2018 issue of Psychosomatic Medicine demonstrates that PTSD is associated with a higher risk of cardiovascular mortality and myocardial infarction (1). Extending these findings, recent evidence also suggests that some patients who experience a life-threatening illness develop illness-induced PTSD (2,3), which as demonstrated by these authors, may worsen disease severity and increase mortality risk. No study has assessed the prevalence of illness-induced PTSD in a population-based sample, and most studies have relied on self-report rather than clinical diagnosis. The DSM-IV suggested that life-threatening illness could cause PTSD, but the DSM-5 (4) is less clear about whether illness should be considered an index trauma. We estimated the prevalence of illness-induced PTSD in a US population-based study and compared sociodemographic and PTSD presentation factors, between participants with illness-induced PTSD versus a traditional conceptualization of PTSD. We analyzed the 2012–2013 National Epidemiologic Survey on Alcohol and Related Conditions (N = 36,309; response rate = 60.1%), a cross-sectional survey administered to noninstitutionalized US civilians 18+ (5). Participants reported on physician-diagnosed illnesses. The research ethics board at the University of Manitoba Bannatyne campus provided ethical approval for the use of these data and all participants provided informed consent. The Alcohol Use Disorder and Associated Disabilities Interview Schedule assessed past-year PTSD in accordance with DSM-5 criteria. We categorized participants with PTSD by their index/worst trauma: serious or life-threatening illness (i.e., illness-induced PTSD) or any other traumatic event (i.e., other trauma-induced PTSD). Weighted prevalence rates and unadjusted odds ratios are reported, comparing the two groups on sociodemographic and clinical risk factors for PTSD. PTSD symptoms are compared using unadjusted linear regression. Data were weighted according to the 2012 American Community Survey to adjust for nonresponse and oversampling, and we conducted Taylor Series Linearization for variance estimation. As displayed in Table 1, the past-year prevalence of any PTSD was 4.7% (95% confidence interval [CI] = 4.33–5.01, n = 1779); of those past-year PTSD cases, 6.5% (95% CI = 5.06–8.36, n = 102) were illness induced. Of the 13.8% of the sample (95% CI = 13.37–14.57, n = 4782) who endorsed a life-threatening medical event, 1% (95% CI = 0.58–1.29) met criteria for past-year illness-induced PTSD. Compared with other trauma-induced PTSD, those with illnessinduced PTSD were older, reported a later age of PTSD onset, and less likely to be female (54.3% vs 68.2%). Illness-induced PTSD presented with significantly fewer re-experiencing, alterations in cognitions and mood, and hyperarousal symptoms, and had higher