Post Traumatic Stress Disorder was first included in DSM in 1980 and since then it has generated a great deal of research interest. It is classified as  an anxiety disorder, yet is different to the other anxiety disorders in that its onset can be related to a very specific trauma and therefore a specific date in time.

The International Classification of Diseases, tenth revision (ICD-10) is published by the World Health Organization (1993) and is the official coding system in the UK.

The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) is published by the American Psychiatric Association. The DSM-IV tends to be used within research and is the American classification system.

Both systems are used in legal proceedings in the UK.

The similarities across both diagnostic systems are:

• exposure to traumatic event,
• persistent re experiencing of the event,
• avoidance symptoms and
• hyperarousal symptoms.

However, there are differences between DSM-IV and ICD-10 in terms of the criteria for Post Traumatic Stress Disorder. The major differences between DSM-IV and ICD-10 criteria are highlighted in the table below (taken from Rosner and Powell 2009)

DSM-IV Criteria	ICD-10 Criteria
A) Event A1) Threat to life of self or others A2) Feelings of helplessness, fear or horror	A) Event A1) Exceptionally threatening or catastrophic event which would cause distress in almost everybody, e.g. being in a war zone.
B) At least one intrusive symptom	B) At least one intrusive symptom
C) At least three symptoms reflecting avoidance or numbing	C) At least one avoidance symptom
D) At least two hyper arousal symptoms	D1) Difficulty remembering D2) At least two hyper arousal symptoms.
E) Duration of symptoms longer than a month, time of onset is not specified	E) Symptoms B, C and D develop within six months after exposure
F) Impairment	F) NO impairment criteria

That is, in DSM-IV, the event criterion involves “threat to life”, along with feelings of helplessness, fear and horror. In ICD-10, the assumption is that certain events, such as being in a war zone, would automatically satisfy the criteria.

In DSM IV there is a greater need to satisfy avoidance or emotional numbing symptoms. This has led to criticism, and the suggestion that DSM-IV is too stringent.

In respect of duration of symptoms there are differences between the two classification symptoms.

Criterion F suggests that impairment in functioning is critical for a diagnosis. That is,  in what way have the symptoms impacted on the persons life (at home / school/ work and so on).  This is not identified as a significant factor in diagnosis for ICD-10.

The above differences have raised the question:

“Does ICD 10 overestimates the prevalence of PTSD?”

An Australian epidemiological study (Andrews et al 2001) found significant differences in diagnosis using the two systems, with only a 35% concordance. The twelve month prevalence of PTSD based on ICD-10 was 7%, compared to 3% based on DSM-IV.

Rosner, Powell and Butollo (2003) and Rosner and Powell (2009) looked at a comparison of PTSD using data collected in Sarajevo following the war. The authors noted, “as expected, the strict application of DSM-IV criteria resulted in the lowest PTSD rates. Ignoring both parts of criterion A, led to a rate increase of 6%”. They went on to say,  “neglecting the duration criteria resulted in an increase of about 5%… reducing the avoidance criterion to two instead of three, only had a relatively small contribution…the event criteria contributed most to the differences in prevalence”.

They concluded that DSM-IV seems better to portray “the current theoretical constructs of PTSD”.

The consensus of opinion from the research that ICD 10 does result in a greater rate of diagnosis. Rates of diagnosis are approximately double that that of DSM IV and therefore when working in the area of personal injury consideration needs to be given to which of the systems the expert is utilizing.

References

Andrews, Slade and Peters (1999) Classification in Psychiatry: ICD10 versus DSM IV. British Journal of Psychiatry, 174, 3-5.

Andres Henderson and Hall (2001) Prevalence, co morbidity and disability and service utilization. British Journal of Psychiatry 78, 145-153.

Peters, Slade and Andrews (1999) A comparison of ICD10 and DSM IV criteria for PTSD. Journal of traumatic stress 12 , 335-343.

Rosner, Powell and Butollo (2003) Post traumatic stress after the siege of Sarajevo. Journal of Clinical Psychology 59, 41-56.

Rosner and Powell, (2009) Does ICD-10 overestimate the prevalence of PTSD? Trauma and Gewalt, Jan28, 3, 2