Measurement of pain: The psychometric properties of the Pain-O-Meter, a simple, inexpensive pain assessment tool that could change health care practices

A self-administered pain assessment tool called the Pain-O-Meter (POM) was developed for the purposes of improving assessment and management of pain in acute and chronic pain patients. The POM is a hard, white, plastic tool that measures 8-in. long by 2-in. wide and 1-in. thick. Two methods for assessing pain are located on the POM. The first is a 10-cm visual analogue scale (POM-VAS) with a moveable marker that patients use to rate their pain. The second is a list of 15 sensory and 11 affective word descriptors (WDS). Each WDS is assigned an intensity value that can be as low as 1 or as high as 5. A pain intensity score is provided for the sensory and the affective WDSs. This psychometric study, which employed correlational and comparative designs, investigated the test-retest reliability and the concurrent and construct validity of the POM-VAS and the POM-WDS in 279 patients with acute or chronic pain. High correlations were found between initial and repeat pain intensity ratings on the POM-VAS (r = 0.88, P < 0.001) and POM-WDS (r + 0.84, P < 0.001) (test-retest reliability). Correlations between the POM-WDS and the McGill Pain Questionnaire (MPQ) (r = 0.69, P < 0.001) and POM-VAS (r = 0.85, P < 0.001) supported the concurrent validity of the POM-WDS. Construct validity was also supported for the Pain-O-Meter by showing that pain scores decreased significantly for POM-WDS (t + 5.53, P < 0.001), and POM-VAS (t = 6.18, P < 0.001) after the patients were treated with pain medication. The use of a pain tool, such as the POM, could improve patient care by facilitating the documentation of pain and evaluation of pain relief measures.