– Posttraumatic stress disorder symptoms triggered by a life-threatening medical illness differ from the more common PTSD, the source of which is an external trauma such as an assault or natural disaster, according to Renee El-Gabalawy, PhD.

“This suggests implications for diagnostic classification. Maybe, in future editions of the DSM, we should think of this as a subtype of PTSD or potentially as a new diagnostic category, although it’s far too early to make any conclusions about that,” Dr. El-Gabalawy said at the annual conference of the Anxiety and Depression Association of America.

Dr. Renee El-Gabalawy

It’s estimated that PTSD occurs in 12%-25% of people who experience a life-threatening medical event.

“This is a fairly staggering proportion of people, and unfortunately this is a very overlooked area in the PTSD literature, almost all of which has been done in critical care units or oncology settings,” said Dr. El-Gabalawy, a psychologist at the University of Manitoba in Winnipeg.

She presented an analysis of data from the 2012-2013 National Epidemiologic Survey on Alcohol and Related Conditions, in which a nationally representative sample composed of 36,309 U.S. adults were interviewed face to face, with the current DSM-5 diagnostic criteria for PTSD being applied using the Alcohol Use Disorder and Association Disabilities Interview Schedule–5 (AUDADIS-5).

A total of 1,779 subjects (4.9%) indicated they had experienced physician-diagnosed PTSD during the previous year. Of those, 6.5% said their PTSD was triggered by an acute life-threatening medical event. The rest were attributed to nonmedical trauma.

There were sharp demographic differences between the two groups. Individuals with medical illness–induced PTSD were older – 35 years old at onset of their first episode, compared with age 23 in the others – with later onset of their PTSD. They were more likely to be men: 45.7% were male, compared with 31.8% for subjects with nonmedical PTSD. Comorbid depression was present in 25.4% of those with medical illness–induced PTSD, and comorbid panic disorder was present in 17%, significantly lower than the 37% and 24.5% rates in individuals with other triggers of PTSD.

Quality of life as measured by the Short Form-12 was similar in the two groups, after the investigators controlled for the number of medical conditions patients had.

Of people with medical illness–induced PTSD, 41% attributed their PTSD to a digestive disease, most often inflammatory bowel disease. In contrast, a digestive condition was present in 19.2% of subjects with nonmedical trauma as the source of their PTSD. Thus, a serious digestive disorder was associated with a 2.4-times increased risk of medical illness–induced PTSD in an analysis adjusted for socioeconomic factors and number of health conditions. Cancer, which was the trigger for 16.1% of cases of medical illness–induced PTSD and which had a prevalence of 5.8% in those with nonmedical sources of PTSD, was associated with a 2.64-times increased risk of medical illness–related PTSD.

“Those odds ratios are quite high for a population-based sample. This was a very dramatic effect,” Dr. El-Gabalawy commented.

The two groups of participants with PTSD had similar intensity of core PTSD symptom clusters with the exception of negative mood/cognition, which figured more prominently in those with medical illness–induced PTSD.

“This is very much in line with my clinical experience, that what’s really predominant in these folks are the maladaptive cognitions, their fear about their future health trajectory,” she said. “I tend to use cognitive processing therapy in these patients. It really taps into those maladaptive cognitions, and I’ve found that my patients are very receptive to this. Cognitive processing therapy might be more advantageous in this situation than prolonged exposure therapy .”

Dr. El-Gabalawy said she is a fan of the Enduring Somatic Threat model of medical illness–induced PTSD developed by Donald Edmondson, PhD, of Columbia University in New York (Soc Personal Psychol Compass. 2014 Mar 5;8[3]:118-34).

“It aligns with the literature and my own clinical experience,” she explained.

Dr. Edmondson’s model draws conceptual distinctions between medical illness–induced PTSD and other causes of PTSD. In medical illness–related PTSD, the trauma has a somatic source, the trauma tends to be chronic, and intrusive thoughts tend to be future oriented and highly cognitive in nature.

“It’s not uncommon that I’ll hear my patients with medical illness–induced PTSD say, ‘I’m really scared my disease is going to get worse.’ And behavioral avoidance is really difficult. Whereas, in the traditional conceptualization of PTSD, the intrusions are often past oriented and elicited by external triggers. Behavioral avoidance of those triggers is possible, but, in illness-related PTSD, arousal is keyed to internal triggers, often somatic in nature, such as heart palpitations,” according to the psychologist.

Her study was supported by the Canadian National Institutes of Health Research and the University of Manitoba. She reported having no financial conflicts.

[email protected]