New ICD-11 Criteria Will Reduce PTSD Diagnoses by 50%

Megan Brooks

May 14, 2018

Proposed changes to the upcoming 11th edition of the International Classification of Diseases (ICD-11) will reduce the proportion of individuals who meet diagnostic criteria for posttraumatic stress disorder (PTSD) by about 50%, a new study suggests.

"Importantly, our data suggest that ICD-11 might miss the moderate, and more easily treatable, cases of PTSD," lead author Anna Barbano, BS, a research associate in the Department of Psychiatry at New York University School of Medicine in New York City, told Medscape Medical News.

"Our data suggest ICD-11 PTSD diagnostic criteria could warrant a little caution if used to strictly sanction treatment coverage," said Barbano.

The study was published online May 14 in Psychological Medicine.

Heterogeneous Population

The ICD is produced under the auspices of the World Health Organization. ICD-11 is currently a beta draft; the final version is expected to be released in June.

ICD-11 PTSD diagnostic rules offer somewhat of a "radical change" from ICD-10 criteria, said Barbano. Whereas ICD-10 takes a fairly broad diagnostic approach and includes 13 symptoms in its diagnostic template, ICD-11 proposes to remove symptoms common to PTSD and other disorders, particularly mood and anxiety disorders (for example, sleep disturbances and irritability), and restrict the criteria to symptoms ostensibly specific to PTSD, she explained.

With the goal of increasing the specificity of the disorder, the proposed ICD-11 template has only six criteria: dissociative flashbacks, nightmares, hypervigilance, exaggerated startle response, avoidance of external reminders, and avoidance of thoughts and feelings associated with the traumatic event.

Barbano and colleagues assessed differences in rates, severity, and overlap of diagnoses using ICD-10 and ICD-11 PTSD criteria in 3863 survivors of traumatic events (mostly motor vehicle accidents). They applied ICD-10 and ICD-11 rules to the Clinician-Administered PTSD Scale (CAPS) at consecutive assessments from the time of the traumatic event to about 15 months after exposure to trauma.

Although there was "very high" overlap (97%) between individuals who were identified as having PTSD on ICD-10 and ICD-11 criteria, ICD-11 identified "only about half as many participants as ICD-10 across assessment intervals," Barbano said. Specifically, 47% to 57% fewer individuals were diagnosed with PTSD under ICD-11 criteria.

In addition, the severity of PTSD symptoms identified by ICD-11 criteria (CAPS total scores) was 31% to 36% higher than those identified by ICD-10 criteria alone. "However, those who were identified only by the ICD-10 still had CAPS scores that were indicative of moderate or threshold PTSD, so pretty symptomatic," Barbano said. On the basis of these findings, she suggested that ICD-11 might miss the moderate cases.

These results suggest clinicians should use caution in strictly applying ICD-11 PTSD criteria, she said.

"People express PTSD and posttraumatic psychopathology in diverse ways. Diagnostic templates are all kind of an approximation of these responses. For this reason, trying to be particularly specific in the operational definition can possibly miss a large proportion of individuals with different symptom phenotypes. Homogeneity may be good for clinical research, but real-world individuals often have more varied responses," said Barbano.

Concerning Findings

Reached for comment, David Spiegel, MD, professor and associate chair of psychiatry and behavioral sciences at Stanford University School of Medicine, Palo Alto, California, said this study was conducted by "leading figures in psychiatric epidemiology and PTSD. The paper is clearly written and deserves to be taken seriously."

The findings, said Spiegel, are "noteworthy and concerning. They show that the ICD-11 criteria for PTSD reduce the proportion of people meeting diagnostic criteria for PTSD by about half, excluding from consideration important and long-held criteria, such as sleep disturbance, intense reaction to reminders of trauma, cognitive and affective symptoms, including negative expectations about the future, and inappropriate guilt. These are core symptoms," said Spiegel.

The new criteria are inferior to the old ones. Dr David Spiegel

"They show that ICD-11 selects for only severe symptomatology, and the difference between ICD-10 and 11 is not due to comorbidity with other disorders such as depression. This problem is even more serious, because PTSD, despite having acute onset, is a chronic disorder, lasting 10 years or more without treatment," Spiegel, a member of the National Academy of Medicine and distinguished life fellow of the American Psychiatric Association, told Medscape Medical News.

"The result of this change will be that many moderately symptomatic people with PTSD will be denied treatment, through lack of recommendation or problems with reimbursement. The new criteria are inferior to the old ones. It has taken decades for us to recognize PTSD as a true psychiatric disorder — diagnosable and treatable. I see these people every week in my practice. It is a shame to artificially restrict recognition and treatment of their disorder," said Spiegel.

The study was funded by a US Public Health Services grant. The authors and Dr Spiegel have disclosed no relevant financial relationships.

Psychol Med. Published online May 14, 2018. Full text

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