A total of 55 older patients and 25 healthy young people met the eligibility criteria and were recruited for the study. This was a convenience sample and both patients and controls were recruited during the study period. Elderly patients and healthy young people had a mean age of 82.4 ± 9.8 and 21.4 ± 1.3 years, respectively (Table 1). Elderly patients had a lower BMI than healthy young people (19.7 ± 3.6 kg/m2 vs. 23.0 ± 3.7 kg/m2, p < .001). The medical data and pressure ulcer risk of older patients are shown in Table 2. In older patients, the Braden and MNA scores were 12.3 ± 3.2 (range, 7–17) and 8.0 ± 2.2 points (range, 1–12 points), respectively. Older patients had a lower-than-normal serum albumin level (3.4 ± 0.5 g/dl).
Table 1
Demographic variables of older patients and healthy young people
Variable | Elderly patients (n = 55) | Healthy young people (n = 25) | p |
Sex | | | | | | | |
Women, n (%) | 32 | (58.2) | 25 | (100.0) | |
Age (years; mean ± SD) | 82.4 | ± | 9.8 | 21.4 | ± | 1.3 | < .000a |
BMI (kg/m2; mean ± SD) | 19.7 | ± | 3.6 | 23.0 | ± | 3.7 | < .001a |
aMann-Whitney U test |
SD, standard deviation; BMI, body mass index |
Table 2
Medical data and pressure ulcer risk of older patients
Variables | | |
Diagnosis (multiple answers) | | | | | | |
Neoplasms, n (%) | 4 | (8.0) | | | |
Endocrine, nutritional, and metabolic diseases, n (%) | 12 | (24.0) | | | |
Dementia in Alzheimer disease, n (%) | 14 | (25.5) | | | |
Extrapyramidal and movement disorders, n (%) | 11 | (20.0) | | | |
Heart diseases, n (%) | 15 | (27.3) | | | |
Cerebrovascular diseases, n (%) | 38 | (69.1) | | | |
Respiratory diseases, n (%) | 12 | (21.8) | | | |
Laboratory test | | | | | | |
Albumin (g/dl)a | 3.4 | ± | 0.5 | 2.1 | - | 4.2 |
Total protein (g/dl)a | 6.7 | ± | 0.7 | 5.2 | - | 7.8 |
Red blood cell (106/dl)a | 3.7 | ± | 0.6 | 2.4 | - | 5.3 |
Hemoglobin (g/dl)a | 11.7 | ± | 2.1 | 7.4 | - | 17 |
Braden scale total score a | 12.3 | ± | 3.2 | 7.0 | - | 17.0 |
Mini Nutritional Assessment a | 8.0 | ± | 2.2 | 1.0 | - | 12.0 |
Pressure ulcer risk factors | | | | | | |
Repositioning individuals in bed, unable, n (%) | 38 | (69.1) | | | |
Repositioning seated individuals, unable, n (%) | 52 | (94.5) | | | |
Bony prominence, yes, n (%) | 16 | (29.1) | | | |
Joint contracture, yes, n (%) | 35 | (63.6) | | | |
Urinary incontinence, yes, n (%) | 50 | (90.9) | | | |
Fecal incontinence, yes, n (%) | 43 | (78.2) | | | |
Edema, yes, n (%) | 24 | (43.6) | | | |
aMean ± SD, range |
SD, standard deviation |
Regarding the presence of pressure ulcer risk factors in older patients, 38 patients were unable to reposition themselves in the bed (69.1%), 50 patients had urinary incontinence (90.9%), and 43 patients had fecal incontinence (78.2%).
The comparison of the 6 skin physiological indices between older patients and healthy young people is shown in Table 3. Skin temperature was significantly higher in older patients at all sites (back, 34.8 °C ± 0.9 °C; sacrum, 34.9 °C ± 0.8 °C; right heel, 29.7 °C ± 3.2 °C; left heel, 29.7 °C ± 3.2 °C) than in healthy young people (back, 33.7 °C ± 1.0 °C; sacral, 33.1 °C ± 1.2 °C; right heel, 25.9 °C ± 2.6 °C; left heel, 25.8 °C ± 2.5 ℃) (p < .001 for all sites). Epidermal water content at the sacrum was significantly higher in older patients than in healthy young people (31.1 ± 10.5 vs. 26.3 ± 6.4 AU, p = .025). Conversely, in the right and left heels, the epidermal water content was lower in older patients than in healthy young people (right heel, 14.8 ± 9.1 AU; left heel, 14.4 ± 8.3 AU vs. right heel, 23.2 ± 10.9 AU; left heel, 20.6 ± 9.0 AU; p < .001 and .003 for the right and left heel, respectively). The epidermal water content was classified as very dry at all sites in both older patients and healthy young people. TEWL values were significantly lower at all sites in older patients (back, 7.1 ± 1.8 g/hm2; sacral, 7.4 ± 3.0 g/hm2; right heel, 17.7 ± 7.1 g/hm2; left heel, 19.4 ± 8.1 g/hm2) than in healthy young people (back, 11.9 ± 7.9 g /hm2; sacral, 9.4 ± 2.9 g/hm2; right heel, 31.0 ± 9.9 g/hm2; left heel, 30.8 ± 8.1 g/hm2) (p < .001 for all sites). In both older patients and healthy young people, the TEWL was classified as very good or good at the sacrum and back. However, in both heels, the TEWL values were normal in older patients and bad in healthy young people. Skin erythema values were significantly higher at the back and sacrum in older patients (back, 225.2 ± 67.2 AU; sacrum, 264.3 ± 81.2 AU) than in healthy young people (back, 172.0 ± 32.4 a.u.; sacrum, 188.6 ± 26.8 a.u.) (p < .001 for both areas). In both older patients and healthy young people, skin erythema was classified as minor at all sites. Skin elasticity was significantly lower at the back and sacrum in older patients (back, 0.61 ± 0.13; sacrum, 0.67 ± 0.11) than in healthy young people (back, 0.86 ± 0.04; sacrum, 0.87 ± 0.05) (p < .001 for both areas). The sacral and right heel skin was significantly thinner in older patients (sacrum, 0.97 ± 0.56 cm; right heel, 0.95 ± 0.24 cm) than in healthy young people (sacrum, 2.27 ± 0.84 cm; right heel, 1.02 ± 0.15 cm) (p < .001 for the sacrum and p = .037 for the right heel).
Table 3
Comparisons of skin physiological indices between older patients and healthy young people
Variable | Elderly patients (n = 55) | | Healthy young people (n = 25) | P |
Mean ± SD | Median | Range | | Mean ± SD | Median | Range |
Skin temperature (℃) | | | | | | | | | | | | | | | | |
Back | 34.8 | ± | 0.9 | (34.8) | 32.7 | - | 36.6 | | 33.7 | ± | 1.0 | (33.8) | 30.5 | - | 35.0 | < .001a |
Sacrum | 34.9 | ± | 0.8 | (34.9) | 32.8 | - | 36.5 | | 33.1 | ± | 1.2 | (33.3) | 30.5 | - | 35.1 | < .001a |
Right heel | 29.7 | ± | 3.2 | (29.9) | 23.6 | - | 36.9 | | 25.9 | ± | 2.6 | (25.5) | 22.0 | - | 30.9 | < .001a |
Left heel | 29.7 | ± | 3.2 | (29.8) | 22.7 | - | 36.7 | | 25.8 | ± | 2.5 | (25.8) | 21.1 | - | 30.8 | < .001a |
Epidermal water content (AU) | | | | | | | | | | | | | | | | |
Back | 32.4 | ± | 10.6 | (33.0) | 14.9 | - | 59.9 | | 36.5 | ± | 16.9 | (32.4) | 16.6 | - | 97.9 | 0.20a |
Sacrum | 31.1 | ± | 10.5 | (29.9) | 6.1 | - | 71.8 | | 26.3 | ± | 6.4 | (26.3) | 16.3 | - | 39.3 | 0.03b |
Right heel | 14.8 | ± | 9.1 | (13.2) | 2.2 | - | 46.7 | | 23.2 | ± | 10.9 | (20.5) | 7.0 | - | 53.6 | < .001b |
Left heel | 14.4 | ± | 8.3 | (12.3) | 3.4 | - | 38.1 | | 20.6 | ± | 9.0 | (18.8) | 7.9 | - | 40.7 | < .001b |
TEWL (g/hm2) | | | | | | | | | | | | | | | | |
Back | 7.1 | ± | 1.8 | (7.0) | 3.8 | - | 13.0 | | 11.9 | ± | 7.9 | (9.4) | 5.5 | - | 38.3 | < .001b |
Sacrum | 7.4 | ± | 3.0 | (7.0) | 2.3 | - | 16.2 | | 9.4 | ± | 2.9 | (9.0) | 5.0 | - | 17.8 | < .001b |
Right heel | 17.7 | ± | 7.1 | (16.8) | 5.4 | - | 36.0 | | 31.0 | ± | 9.9 | (30.3) | 15.3 | - | 53.9 | < .001b |
Left heel | 19.4 | ± | 8.1 | (18.7) | 6.9 | - | 53.2 | | 30.8 | ± | 8.1 | (28.5) | 18.2 | - | 45.9 | < .001b |
Skin erythema (AU) | | | | | | | | | | | | | | | | |
Back | 225.2 | ± | 67.2 | (217.5) | 110.3 | - | 386.5 | | 172.0 | ± | 32.4 | (177.0) | 88.8 | - | 220.0 | < .001a |
Sacrum | 264.3 | ± | 81.2 | (248.3) | 150.5 | - | 487.8 | | 188.6 | ± | 26.8 | (190.0) | 131.5 | - | 232.0 | < .001b |
Right heel | 241.3 | ± | 90.7 | (231.0) | 97.5 | - | 571.5 | | 238.1 | ± | 48.8 | (238.0) | 156.0 | - | 350.3 | 0.58b |
Left heel | 251.6 | ± | 78.5 | (246.0) | 120.3 | - | 500.8 | | 252.8 | ± | 55.6 | (240.8) | 162.3 | - | 376.8 | 0.80b |
Skin elasticity (AU) | | | | | | | | | | | | | | | | |
Back | 0.61 | ± | 0.13 | (0.61) | 0.30 | - | 0.82 | | 0.86 | ± | 0.04 | (0.86) | 0.78 | - | 0.93 | < .001a |
Sacrum | 0.67 | ± | 0.11 | (0.68) | 0.43 | - | 0.88 | | 0.87 | ± | 0.05 | (0.87) | 0.72 | - | 0.94 | < .001a |
Right heel | 0.60 | ± | 0.10 | (0.62) | 0.22 | - | 0.80 | | 0.65 | ± | 0.05 | (0.65) | 0.51 | - | 0.74 | 0.06b |
Left heel | 0.63 | ± | 0.08 | (0.63) | 0.48 | - | 0.83 | | 0.63 | ± | 0.05 | (0.64) | 0.50 | - | 0.73 | 0.96a |
Skin thickness (cm) | | | | | | | | | | | | | | | | |
Sacral | 0.97 | ± | 0.56 | (0.78) | 0.30 | - | 2.93 | | 2.27 | ± | 0.84 | (2.1) | 0.80 | - | 4.41 | < .001b |
Right heel | 0.95 | ± | 0.24 | (0.93) | 0.60 | - | 1.80 | | 1.02 | ± | 0.15 | (1.0) | 0.67 | - | 1.25 | < .001b |
Left heel | 0.95 | ± | 0.27 | (0.91) | 0.53 | - | 1.95 | | 0.98 | ± | 0.14 | (1.0) | 0.71 | - | 1.28 | 0.47b |
aIndependent t-test; bMann-Whitney U test. AU, arbitrary units, TEWL, transepidermal water loss |
In older patients, the relationship between demographic and laboratory data and skin physiological indices was examined (data not shown). A moderate negative correlation was observed between heel skin temperature and age (right heel, r = − .451, p < .001; left heel, r = − .541, p < .001). Skin temperature and BMI showed a weak negative correlation at the back and sacrum (back, r = − .394, p = .003; sacrum, r = − .382, p = .005). Weak positive correlations were observed between sacral erythema and age (r = .319, p = .025) and between sacral erythema and total protein level (r = − .311, p = .025). Moderate and weak positive correlations were observed between back (r = .445, p < .001) and sacral (r = .273, p < .045) skin elasticity and serum albumin levels, respectively. On the contrary, there was a weak negative correlation between back skin elasticity and age (r = − .355, p = .009). Skin thickness and BMI showed a moderately positive correlation at all sites (sacrum, r = .506, p < .001; right heel, r = .482, p < .001; left heel, r = .460, p < .001). Finally, sacral skin thickness and serum albumin level showed a weak positive correlation (r = .282, p = .041). No other correlations were observed.
The statistical power of the significant differences in skin elasticity and thickness was high (skin elasticity: back, .92; sacrum, .90; sacral skin thickness: .76). The statistical power of the moderate correlations between skin physiological indices and pressure ulcer risk in older patients ranged from .94 to .99.