Filming the children
The next thing we did was to film 29 children at home or at their school. We wanted to see if the PPP scale could tell the difference between children who very rarely had pain and those who frequently had quite severe pain. Three of us used the PPP to rate the children on video-film and found that there was considerable agreement on the total score, though we differed sometimes on individual items of behaviour. We found that as our estimate of the children's pain increased so did the score on the behaviour rating scale. In addition, the PPP score increased in line with the assessments of the child's pain that the parents had made during the filming. The children who had been reported by their parents to have severe pain frequently did have significantly higher PPP scores than those who had been reported not to have pain.
Cortisol as a measure of pain
When children (or adults) have pain the body recognises this as stressful. When we are stressed we can have increases in some of the hormones our body produces. One of these hormones is cortisol and we are able nowadays to measure cortisol from samples of saliva. One of the things we wanted to find out was whether we would see increases in salivary cortisol in the children with higher pain scores. We did in fact see an increase in cortisol with pain, in some of the children, though not all. We think this may be because there are a lot of other things that affect the body's response to stress so the relationship between pain (or stress) and the hormonal response is not straightforward. We hope to do some more research into this relationship in the future. Unfortunately getting results for salivary cortisol can take a long time, so it is a test that is useful for research but not so useful in clinical settings. However, the fact that in general, there was an increase in the behaviour rating score when the level of cortisol was increased encouraged us to believe that our tool is measuring pain, or at least stress of some kind.
We have written a paper to describe this stage in the development of the Paediatric Pain Profile. This is the reference:
Hunt, A, Wisbeach, A., Seers, K., Goldman, A., Crichton, N., Perry, L. & Mastroyannopoulou, K. (2007) Development of the Paediatric Pain Profile: Role of video analysis and saliva cortisol in validating a tool to assess pain in children with severe neurological disability. Journal of Pain and Symptom Management, 33, 276-289.
The abstract is available by clicking on the abstract link below
Poster presented at the 6th International Symposium on Paediatric Pain. Sydney, June 2003.PPP Stage2 PPP Stage4