Whiplash Patients' Responses on the Impact of Events Scale-R - Congruent With Pain or PTSD Symptoms?

OBJECTIVES: Post-traumatic stress disorder (PTSD) symptoms are common among people with whiplash following a motor vehicle crash. The Impact of Events Scale - Revised (IES-R) screens for PTSD symptoms with psychologist referral recommended for above-threshold scores. Recent data indicate that PTSD symptoms post-whiplash may relate more to pain and disability than the crash itself. This study explored the interpretation of IES-R items by people with whiplash to establish whether responses relate to the crash or to whiplash pain and disability.

METHODS: Adults with whiplash scoring >24 on the IES-R were eligible. The Three-Step Test-Interview technique was used and responses analysed using content analysis. A coding framework was developed, comprising five categories: "congruent" - responses related to the crash; "incongruent" - responses did not relate to the crash; "ambiguous" - responses were both congruent and incongruent; "confusion" - participants misunderstood the item content; "not applicable" - irrelevancy of items to participants' circumstances.

RESULTS: The 15 participants (mean IES-R= 37/88) were inclined to respond congruently to specific PTSD items and incongruently to non-specific PTSD items. Participants were more inclined to rate non-specific PTSD items in terms of pain and disability, e.g., >60% responded incongruently to item 2: "I had trouble staying asleep"; item 4: 'I felt irritable and angry"; item 15: "I had trouble falling asleep"; and item 18: "I had trouble concentrating".

DISCUSSION: Incongruent responses on non-specific PTSD items may inadvertently inflate levels of PTSD symptoms measured with the IES-R for some whiplash patients, raising implications for the assessment and treatment of the psychological sequelae of whiplash.