in clinical and research applications. The short form is typically what is referred to when the BPI is cited in research, and it is the version we describe below. Most psychometric evaluations of the BPI have been performed on the short form.
Scoring the Brief Pain Inventory as an Outcome Measure
A recent consensus panel recommended that the two domains measured by the BPI— pain intensity (severity) and the impact of pain on functioning (interference)— be included as outcomes in all
How to Score the BPI: Pain Severity
The BPI assesses pain at its “worst,”“least,”“average,”and “now” (current pain). In clinical trials, the items “worst”and “average” have each been used singly to represent pain severity. A composite of the four pain items (a mean severity score) is sometimes presented as supplemental information. The use of these single items is supported by the IMMPACT recommendations for assessing pain in clinical trials (Dworkin et al., 2005; Turk et al., 2006; Dworkin et al., 2008) and by the FDA Draft Guidance for Industry:
How to Score the BPI: Pain Interference
The BPI measures how much pain has interfered with seven daily activities, including general activity, walking, work, mood, enjoyment of life, relations with others, and sleep. BPI pain interference is typically scored as the mean of the seven interference items. This mean can be used if more than 50%, or four of seven, of the total items have been completed on a given administration.
We are exploring the utility of scoring the activity and affective dimensions described above (WAW and REM, see diagram [link]) as arithmetic means of these sets of items.
How to Score the BPI: Other Items
The item, “Throughout our lives, most of us have had pain from time to time (such as minor headaches, sprains, and toothaches). Have you had pain other than these everyday kinds of pain today?”is a YES/NO preliminary screening question at the beginning of the BPI. This item is optional and we have not evaluated its psychometric properties. The BPI also asks the patient to indicate the percentage of relief provided by pain treatments or medications, but we have not found this item to be very useful in our studies.
Psychometric Properties of the Brief Pain Inventory
Dimensions of the BPI: Two-Factor Structure
Several approaches have explored the underlying dimensions of the BPI. As described above, the BPI was designed to capture two dimensions of pain: severity and interference. The BPI was also intended to capture two components of interference— activity and affect (emotions).
One of the first studies of the dimensions of the BPI compared the factor structure of four language versions of the BPI used to assess cancer pain in the United States, Mexico, the Philippines, and Vietnam (Cleeland, 1990). Factor analysis was applied to the matrix of intercorrelations of the item scores of each sample. For each language version, the same two factors emerged with an eigenvalue greater than 1: the first factor comprised the pain interference items and the second factor comprised the pain severity items. The similarity of the factor loading among the language versions indicated that patients experiencing cancer and pain, living in various countries and speaking various languages, responded to the items in a similar fashion.
This
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