Differences in pain measures by mini-mental state examination scores of residents in aged care facilities: examining the usability of the Abbey pain scale-Japanese version.

The validity and reliability of the Abbey Pain Scale-Japanese version (APS-J) have been examined. However, the range of cognitive levels for which the APS-J can be accurately used in older adults has not been investigated. This study aimed to examine the differences between total/item scores of the APS-J and Mini-Mental State Examination (MMSE) scores of residents in aged care facilities who self-reported the presence or absence of pain. This descriptive study included 252 residents in aged care facilities. Self-reported pain, MMSE scores, and item/total APS-J scores for pain intensity were collected. The MMSE scores were used to create four groups on the basis of the cognitive impairment level. Self-reports of pain and the APS-J scores were compared with different MMSE score groups. The total APS-J score for pain intensity as well as scores for individual items such as "vocalization" and "facial expression" were significantly higher in those who reported pain than in those reporting no pain across all MMSE groups. The total APS-J score and item scores for "vocalization," "change in body language," and "behavioral changes" showed significant differences in the four MMSE groups. Pain intensity tended to be overestimated by the APS-J, especially among those with low MMSE scores. The APS-J can be used to assess pain intensity in residents despite their cognitive levels. However, caution is required when using it to compare scores among older adults with different cognitive capacity because of the possibility of overestimation of pain among residents with low cognitive capacity.