Psychometric evaluation of selected pain intensity scales for use with cognitively impaired and cognitively intact older adults.

The purpose of this study was to determine the reliability and validity of selected pain intensity scales such as the Faces Pain Scale (FPS), the Verbal Descriptor Scale (VDS), the Numeric Rating Scale (NRS), and the Iowa Pain Thermometer (IPT) to assess pain in cognitively impaired older adults. A descriptive correlational design was used, and a convenience sample of 66 volunteers age 60 and older residing in assisted living facilities in the South was recruited for this study. The sample included 22 (33%) men and 44 (67%) women, with a mean age of 76. Ninety-eight percent (65) of the sample comprised Caucasian participants, with the exception of 1 African-American man. Seventy percent (47) completed high school and/or college. The mean Mini Mental State Exam (MMSE) score was 16, with a range of 1 to 29. Eighty-five percent scored 24 or lower, indicating some degree of cognitive impairment. The remaining 15% were cognitively intact. All but one participant could use each scale to rate their pain. Concurrent validity of the VDS, NRS, and IPT was supported with Spearman rank correlation coefficients ranging from .78 to .86 in the cognitively impaired group. The FPS, however, demonstrated weak correlations with other scales when used with the impaired group, ranging from .48 to .53. In the cognitively intact group, strong correlations ranging from .96 to .97 were found among all of the scales. Test-retest reliability at a 2-week interval was acceptable in the cognitively intact group (Spearman rank correlations ranged from .67 to .85) and unacceptable for most scales in the cognitively impaired group (correlations ranged from .26 to .67). When asked about scale preference, both the cognitively impaired and the intact groups preferred the IPT and the VDS. This study revealed that cognitive impairment did not inhibit participants' ability to use a variety of pain intensity scales, but the stability issue must be considered.