Difficulty in assessing pain is one common barrier that can inhibit effective treatment. The pain scales are recommended to be used by GP’s and Accident and Emergency staff and may well also prove useful in a wider range of situations in which the communication of pain is necessary.
Because pain often fluctuates over time, a high index of test-retest reliability is not the goal – it might indicate insensitivity to change rather than reliability across time. As single item scales, there is no question of internal consistency, and as self-report, there is no inter-rater reliability. What helps to achieve reliability is that the scale and the response options are easy to understand, and in this, it is somewhat better than the visual analogue scale.
Because pain is a subjective experience there is no “gold standard” criterion for validity. However, in a broad sense these pain ratings do bear the expected relationships to related variables, such as disability and mood, and are also correlated with the amount of activation in certain areas of the brain concerned with pain processing [Coghill RC, McHaffie JG, Yen Y-F (2003) Neural correlates of interindividual differences in the subjective experience of pain. Proceedings of the National Academy of Sciences 100 8538-8542].
© The British Pain Society 2006-2007-2008