Sex and age differences in mechanical, thermal and wetness perception across skin sites at risk of pressure ulcers: A quantitative sensory testing study

Pressure ulcers can be common in the elderly, and loss of sensation can play a fundamental role in the development of these injuries. The aim of this study was to assess the effects of age and sex on non-noxious thermal and wetness perception (via magnitude estimation), alongside pressure- and thermal-pain thresholds, at the heel, sternum and sacrum, which are skin sites typically at risk for pressure ulcers. A cross-sectional study was performed on 34 younger adults [15 females, 22.1 (1.7) years old] and 17 older adults [eight females, 55.5 (5.3) years old]. We found that: (1) pressure pain thresholds (F_2,24 = 16.60, P < 0.001) and heat pain thresholds (F_2,24 = 4.23, P = 0.027) differed in relationship to age, but only at the heel and sacrum, principally with higher thresholds in the older adults. Furthermore, when collapsed by skin site, we found that females had lower pressure pain thresholds (-157 kPa; P = 0.011) and heat pain thresholds (-1.54°C; P = 0.008) than males. Considering hygrosensation, it was typically higher in the young adults, and the heel was the skin site least sensitive to both thermal and hygrosensation. The results of this study indicate that sensory alterations could be present in skin sites at risk of pressure ulcers; in particular, the heel presented less intensity of sensations to painful and non-noxious stimuli. As such, according to these findings, male sex and age can result in reduced intensities of sensations, which might predispose to a higher risk of pressure ulcers, especially on the heel.