Pain intensity assessment in older adults: use of experimental pain to compare psychometric properties and usability of selected pain scales with younger adults.

OBJECTIVES: To determine: (1) the psychometric properties and utility of 5 types of commonly used pain rating scales when used with younger and older adults, (2) factors related to failure to successfully use a pain rating scale, (3) pain rating scale preference, and (4) factors impacting scale preference.
METHODS: A quasi-experimental design was used to gather data from a sample of 86 younger (age 25-55) and 89 older (age 65-94) adult volunteer subjects. Responses of subjects to experimentally induced thermal stimuli were measured with the following pain intensity rating scales: vertical visual analog scale (VAS), 21-point Numeric Rating Scale (NRS), Verbal Descriptor Scale (VDS), 11-point Verbal Numeric Rating Scale (VNS), and Faces Pain Scale (FPS).
RESULTS: All 5 pain scales were effective in discriminating different levels of pain sensation; however the VDS was most sensitive and reliable. Failure rates for pain scale completion were minimal, except for the VAS. Although age did not impact failure to properly use this pain intensity rating scale, but rather those conditions more commonly associated with advanced age, including cognitive and psychomotor impairment did. The scale most preferred to represent pain intensity in both cohorts of subjects was the NRS, followed by the VDS. Scale preference was not related to cognitive status, educational level, age, race, or sex.
CONCLUSION: Although all 5 of the pain intensity rating scales were psychometrically sound when used with either age group, failures, internal consistency reliability, construct validity, scale sensitivity, and preference suggest that the VDS is the scale of choice for assessing pain intensity among older adults, including those with mild to moderate cognitive impairment.