Frail Older Individuals Maintaining a Steady Standing Position: Associations Between Sway Measurements with Frailty Status Across Four Different Frailty Instruments

Figures & data

Table 1 Characteristics of the Patients Stratified into a Younger and an Older Group According to the Median Age of the Patients of 82.98 Years

Characteristics	Age < Median	N	Age ≥ Median	N	P-value
Female (%, n)	52.5, 32	61	61.3, 38	62	0.323^b
Age (years)	77.29±3.8	61	87.4±3.3	62	<0.001^a
Height (cm)	165.5±9.7	61	162.9±9.7	62	0.108^a
Weight (kg)	73.5±15.9	61	67.9±10.7	62	0.106^a
BMI (kg/m2)	26.8±4.9	61	25.7±3.9	62	0.252^a
MMSE (points)	27.2±1.9	61	26.0±3.1	62	0.077^a
GDS (points)	3.7±2.8	61	2.7±2.0	62	0.029^a
Barthel index (points)	88.4±9.2	61	82.3±12.9	62	0.008^a
TUG (seconds)	17.8±8.2	61	19.4±9.8	62	0.204^a
POMA (points)	20.9±3.8	61	20.3±3.6	62	0.613^a
WSEO Length of sway (mm)	444.1±207.1	61	538.7±301.2	62	0.128^a
WSEO Area of sway (mm^2)	291.1±209.1	61	386.3±434.7	62	0.183^a
WSEO Mean speed (mm/s)	14.8±6.4	61	18.2±9.0	62	0.113^a
WSEC Length of sway (mm)	749.8±470.9	60	922.2±637.4	61	0.464^a
WSEC Area of sway (mm^2)	774.4±852.1	60	862.4±1095.4	61	0.992^a
WSEC Mean speed (mm/s)	26.1±13.7	60	31.3±20.8	61	0.408^a
NSEO Length of sway (mm)	660.9±369.5	58	802.4±407.8	59	0.028^a
NSEO Area of sway (mm^2)	582.7±761.1	58	620.8±479.7	59	0.190^a
NSEO Mean speed (mm/s)	22.3±12.3	58	27.3±14.5	59	0.023^a
NSEC Length of sway (mm)	2417.9±1355.4	45	2822.1±1480.3	44	0.127^a
NSEC Area of sway (mm^2)	1643.1±1478.3	45	1884.6±1589.8	44	0.264^a
NSEC Mean speed (mm/s)	40.7±18.9	45	47.7±22.7	44	0.127^a
Frailty phenotype (FP) (%, n)	11.5, 7	61	11.3, 7	62	0.974^b
Clinical frailty scale (CFS)	4.2±2.8	61	4.7±1.3	62	0.023^a
FI-CGA (-)	0.28±0.09	61	0.34±0.10	62	0.009^a
FI (-)	0.33±0.09	61	0.36±0.08	62	0.058^a
Cancer (%, n)	17.1, 6	61	9.5, 7	62	0.974^b
Stroke (%, n)	11.4, 4	61	16.2, 12	62	0.326^b
Heart failure (%, n)	34.3, 12	61	44.6, 33	62	0.636^b
Renal/Kidney disease (%, n)	62.3, 38	61	80.6, 50	62	0.025^b
Myocardial infarction (%, n)	16.4, 10	61	19.4, 12	62	0.067^b
Diabetes mellitus (%, n)	25.7, 9	61	28.4, 21	62	0.395^b
Chronic lung disease (%, n)	17.1, 6	61	23.0, 17	62	0.107^b
A fall (%, n)	48.6, 17	61	71.6, 53	62	0.235^b
Medication > 5 (%, n)	82.9, 29	61	86.5, 64	62	0.412^b
Institutionalized (%, n)	2.9, 1	61	10.8, 8	62	0.710^b

Notes: Values are: mean, ± SD standard deviation, (%, n) percentage and total number. ^aP-values for Mann–Whitney-U- Test, ^bp-values for Chi–square Test, a two-tailed P value < 0.05 was considered statistically significant. Age, height and weight = on the day of analysis, Barthel index = Hamburger Classification Manual for the Barthel index in geriatrics at hospital discharge (range 0–100), TUG = Timed Up & Go at hospital discharge, POMA = Performance-Oriented Mobility Assessment at hospital discharge (range 2–28), MMSE = Mini-Mental State Examination at hospital discharge (range 0–30), GDS = Geriatric Depression Scale at hospital discharge (range 1–15), FI-CGA = 14-item Frailty Index based on a comprehensive geriatric assessment, FI = 47-item Frailty Index.

Abbreviations: BMI, body mass index; WSEO, wide stand eyes open; WSEC, wide stand eyes closed; NSEO, narrow stand eyes open; NSEC, narrow stand eyes closes.

Table 2 Force Plate Variables and the Frailty Phenotype (FP)

Force Plate Variables	Robust			Pre-Frail				Frail				P-value
	Mean ± SD	95% CI	n	Mean ± SD	95% CI	Effect Size (a)	n	Mean ± SD	95% CI	Effect Size (b)	n
Wide stand, eyes open			35				74				14
Length of sway (mm)	403.1±214.9	329.3–476.9		517.7±269.8	455.1–580.2	0.5		567.6.±287.2	410.7–742.4	0.8		0.014
Area of sway (mm^2)	246.8±172.1	187.6–305.9		334.4±231.4	280.8–388.4	0.5		594.6±799.0	133.3–1055.9	2.0		0.060
Mean speed (mm/s)	13.7±7.0	11.3–16.2		17.3±9.6	15.1–19.6	0.5		19.0±9.3	13.6–24.4	0.7		0.024
Wide stand, eyes closed			35				73				13
Length of sway (mm)	753.3±616.8	541.4–965.2		885.9±496.9	770.0–1001.9	0.2		863.1± 895.5	322.0–1404.3	0.2		0.121
Area of sway (mm^2)	669.3±864.3	372.4–966.2		816.6±822.5	624.7–1008.5	0.2		1105.8 ±1854.7	1499.4–2226.6	0.5		0.116
Mean speed (mm/s)	25.8±18.7	19.3–33.2		29.5±16.2	25.6–33.2	0.2		33.4±0.24.6	17.3–47.5	0.4		0.197
Narrow stand, eyes open			35				69				13
Length of sway (mm)	619.5±358.3	496.4–742.6		764.3±402.7	667.6–861.1	0.4		865.5±395.1	626.7–1104.2	0.7		0.021
Area of sway (mm^2)	576.8±927.8	258.1–895.5		579.8±435.6	475.1–684.4	0		787.0±557.8	450.0–1124.1	0.2		0.068
Mean speed (mm/s)	21.5±12.4	17.2–25.7		25.7±14.1	22.3–29.1	0.3		29.0±13.1	21.0–36.9	0.6		0.052
Narrow stand, eyes closed			32				47				10
Length of sway (mm)	2463.4±1523.1	1914.3–3012.5		2590.2±1187.0	2241.7–2938.7	0.1		3241.2±1500.3	2167.9–4314.4	0.5		0.188
Area of sway (mm^2)	1626.9±1453.3	1103.0–2150.9		1552.9±1028.0	1251.1–1854.76	0		3181.2±2774.3	994.1–4771.9	1.1		0.141
Mean speed (mm/s)	41.5±21.5	33.7–49.2		43.8±19.9	38.0–71.2	0.1		54.3±23.7	39.7–48.6	0.6		0.192

Notes: Values are: mean, ± SD = standard deviation and number of patients (n); Effect size (a) = [Mean of Pre-frail]– [Mean of Robust]/[SD of Robust]; Effect size (b) = [Mean of Frail]– [Mean of Robust]/[SD of Robust]; P-values for Kruskal-Wallis-Test, a two-tailed P value <0.05 were considered statistically significant.

Table 3 Force Plate Variables and the Clinical Frailty Scale (CFS)

Force Plate Variables	Not Frail (CFS<5)			Frail (CFS ≥ 5)				P-value
	Mean ± SD	95% CI	n	Mean ± SD	95% CI	Effect Size	n
Wide stand eyes open			67				56
Length of sway (mm)	455.2±243.2	395.8–514.5		535.6±279.0	460.4–610.3	0.3		0.046
Area of sway (mm^2)	278.6±188.9	232.6–324.7		411.4±457.9	288.8–534.1	0.7		0.110
Mean speed (mm/s)	15.2±8.3	13.2–17.2		18.1±9.7	15.5–20.6	0.4		0.046
Wide stand, eyes closed			66				55
Length of sway (mm)	798.4±553.5	662.3–934.5		934.3±570.7	778.5–1090.1	0.3		0.082
Area of sway (mm^2)	741.2±923.9	514.1–968.3		881.3±1064.1	514.1–968.3	0.2		0.148
Mean speed (mm/s)	26.5±17.1	22.3–30.7		31.5±18.5	19.1–48.7	0.3		0.081
Narrow stand, eyes open			64				53
Length of sway (mm)	675.9±383.8	580.0–771.8		800.3±399.1	690.3–910.3	0.3		0.034
Area of sway (mm^2)	550.7±706.9	374.1–727.7		663.8±529.0	517.9–809.6	0.2		0.083
Mean speed (mm/s)	22.9±13.7	19.5–26.3		27.1±13.2	23.4–30.7	0.3		0.027
Narrow stand, eyes closed			52				37
Length of sway (mm)	2574.5±1402.2	2184.2–2964.9		2678.0±1303.4	2243.9–3113.0	0.1		0.566
Area of sway (mm^2)	1695.0±1387.3	1308.7–2081.2		1857.4±1727.3	1236.2–2375.5	0.1		0.588
Mean speed (mm/s)	43.0±20.8	37.8–48.7		45.9±21.6	38.6–53.0	0.1		0.479

Notes: Values are: mean, ± SD = standard deviation and number of patients (n); Effect size = [Mean of Frail (CFS ≥5)]– [Mean of not Frail (CFS<5)]/[SD of not frail (CFS <5)]; P-values for Mann–Whitney U-Test, a two-tailed P value <0.05 were considered statistically significant.

Table 4 Force Plate Variables and the 14-Item Frailty Index Based on a Comprehensive Geriatricassessment (FI-CGA)

Force Plate Variables	FI-CGA < Median			FI-CGA ≥ Median				P-value
	Mean ± SD	95% CI	n	Mean ± SD	95% CI	Effect Size	n
Wide stand, eyes open			61				62
Length of sway (mm)	447.2±247.4	401.4.7 −520.9		535.6±270.6	467.3–618.7	0.4		0.014
Area of sway (mm^2)	305.7±417.3	227.1–403.7		371.9±251.0	304.6–453.0	0.2		0.014
Mean speed (mm/s)	15.0±8.0	13.5–17.5		18.8±9.8	15,5–21.0	0.5		0.025
Wide stand, eyes closed			59				61
Length of sway (mm)	779.3±523.5	678.6–922.6		937.2±592.8	775.4–1140.2	0.3		0.038
Area of sway (mm^2)	786.7±1085.1	550.5–1010.3		850.5±874.8	596.8–1170.6	0.1		0.074
Mean speed (mm/s)	26.4±17.1	23.0–31.1		31.0±18.3	26.1–37.1	0.3		0.067
Narrow stand, eyes open			59				58
Length of sway (mm)	695.1±401.1	61.2 −818.9		770.0±386.6	667.7 −850.8	0.2		0.104
Area of sway (mm^2)	602.0±784.8	436.2 −774.3		601.8±432.9	465.9 −726.5	0		0.144
Mean speed (mm/s)	23.5±13.3	20.8–27.9		26.1±13.9	22.6–28.6	0.2		0.143
Narrow stand, eyes closed			47				42
Length of sway (mm)	2402.8±1275.4	2063.0–2692.8		2858.2±1416.3	2504.8–3628.2	0.4		0.051
Area of sway (mm^2)	1590.7±1297.9	1254.4–2059.9		1954.7±1751.0	1397.1–2522.0	0.3		0.086
Mean speed (mm/s)	41.3±21.4	35.5–46.2		47.4±20.4	42.5–58.2	0.3		0.060

Notes: Median FI-CGA was 0.32143; Values are: mean, ± SD = standard deviation and number of patients (n); Effect size = [Mean of FI-CGA ≥Median]– [Mean of FI-CGA < Median]/[SD of FI-CGA < Median]; P-values for Mann–Whitney U-Test, a two-tailed P value <0.05 were considered statistically significant.

Table 5 Force Plate Variables and the Frailty Index (FI)

Force Plate Variables	FI < Median			FI ≥ Median				P-value
	Mean ± SD	95% CI	n	Mean ± SD	95% CI	Effect Size	n
Wide stand, eyes open			60				63
Length of sway (mm)	446.7±232.3	386.7 −506.7		534.7±282.8	463.4–605.9	0.4		0.054
Area of sway (mm^2)	283.4±208.7	229.4–333.73		392.2±430.5	283.8–500.6	0.5		0.129
Mean speed (mm/s)	15.2±8.4	13.1–17.4		17.7±9.5	15,3–20.1	0.3		0.069
Wide stand, eyes closed			59				61
Length of sway (mm)	799.1±587.6	645.9–952.2		918.1±536.5	780.7–1055.5	0.2		0.048
Area of sway (mm^2)	750.3±931.5	507.5–993.0		885.8±1028.4	622.4–1149.2	0.2		0.117
Mean speed (mm/s)	26.8±18.5	22.0–31.6		30.7±17.1	26.3–35.1	0.2		0.056
Narrow stand, eyes open			58				59
Length of sway (mm)	651.9±373.4	553.8 −750.1		811.2±401.0	706.7 −915.7	0.4		0.007
Area of sway (mm^2)	533.7±746.2	337.5 −729.9		669.0±493.6	540.3 −797.6	0.2		0.005
Mean speed (mm/s)	22.5±13.9	18.9–26.2		27.0±13.1	23.6–30.4	0.3		0.013
Narrow stand, eyes closed			48				41
Length of sway (mm)	2387.3±1425.9	1973.3–2801.3		2887.5±1230.6	2499.1–3276.0	0.4		0.013
Area of sway (mm^2)	1466.3±1300.8	1088.6–1844.0		2109.0±1713.7	1568.3–2650.1	0.5		0.008
Mean speed (mm/s)	40.9±22.4	34.4–47.4		47.9±19.0	41.9–53.9	0.3		0.021

Notes: Median FI was 0.34574; values are: mean, ± SD = standard deviation and number of patients (n); Effect size = [Mean of FI ≥ Median]– [Mean of FI < Median]/[SD of FI < Median]; P-values for Mann–Whitney U-Test, a two-tailed P value <0.05 were considered statistically significant.

Figure 1 Association between length of sway during the task wide stand eyes open (WSEO) and frailty status according to the frailty phenotype (P = 0.014).

Figure 2 Association between length of sway during the task narrow stand eyes open (NSEO) and frailty status according to the clinical frailty scale (CFS) (P = 0.034).

Figure 3 Association between length of sway during the task wide stand, eyes open (NSEO) and frailty status, according to the frailty index based on a comprehensive geriatric assessment (FI-CGA) (P = 0.014).

Figure 4 Association between length of sway during the task narrow stand, eyes open (NSEO) and frailty status according to the frailty index (FI) (P = 0.007).

Table 6 Correlation Analysis Between Force Plate Variables and the Four Different Frailty Instruments

Force Plate Variables	FP			CFS			FI-CGA			FI
	r	p-value	n	r	p-value	n	r	p-value	n	r	p-value	n
Wide stand, eyes open			123			123			123			123
Length of sway (mm)	0.26	0.003		0.18	0.043		0.27	0.002		0.25	0.006
Area of sway (mm^2)	0.21	0.018		0.18	0.049		0.25	0.006		0.24	0.009
Mean speed (mm/s)	0.25	0.006		0.19	0.034		0.25	0.005		0.22	0.014
Wide stand, eyes closed			120			120			120			120
Length of sway (mm)	0.19	0.040		0.13	0.157		0.24	0.010		0.20	0.026
Area of sway (mm^2)	0.18	0.048		0.12	0.210		0.19	0.034		0.21	0.024
Mean speed (mm/s)	0.16	0.084		0.13	0.148		0.21	0.019		0.18	0.044
Narrow stand, eyes open			117			117			117			117
Length of sway (mm)	0.26	0.005		0.18	0.058		0.23	0.011		0.23	0.012
Area of sway (mm^2)	0.21	0.021		0.19	0.037		0.20	0.034		0.25	0.008
Mean speed (mm/s)	0.23	0.014		0.19	0.044		0.22	0.019		0.20	0.035
Narrow stand, eyes closed			89			89			89			89
Length of sway (mm)	0.18	0.093		0.09	0.410		0.26	0.013		0.19	0.071
Area of sway   (mm^2)	0.14	0.189		0.12	0.260		0.22	0.040		0.19	0.072
Mean speed (mm/s)	0.16	0.124		0.10	0.356		0.25	0.017		0.16	0.144

Notes: FP = Frailty Phenotype (Fried et al 2001), CFS = Clinical Frailty scale (Rockwood et al 2007), FI-CGA = 14-item Frailty Index based on a comprehensive geriatric assessment, FI = 47-item Frailty Index; r = Spearman (bivariate correlation), a two-tailed P value <0.05 was considered statistically significant.

Table 7 Force Plate Variables and Risk Factors for Frailty Part 1

Force Plate Variables	MMSE			GDS			BARTHEL			TUG			CIRS (Median = 11)
	> 23	≤ 23	P	< 5	≥ 5	P	100	< 100	P	≥ 10	< 10	P	< 11	≥ 11	P
	Mean ± SD			Mean ± SD			Mean ± SD			Mean ± SD			Mean ± SD
n	106	17					12	111		114	9		61	62
Wide stand, eyes open
Length of sway (mm)	469.0±247.5	633.6 ±311.6	0.021	501.3 ±271.2	459.5 ±230.2	0.550	330.0 ±89.6	509.3 ±268.7	0.013	503.1 ±266.6	348.7 ±137.6	0.035	464.6 ±264.2	518.5 ±259.4	0.081
Area of sway (mm^2)	327.2±353.5	409.0 ±275.2	0.124	351.6 ±375.0	296.5 ±205.5	0.662	161.8 ±47.7	358.3 ±356.5	0.010	347.5 ±353.2	232.7 ±166.1	0.212	361.6 ±441.5	317.0 ±209.3	0.854
Mean speed (mm/s)	15.7±8.2	21.7±12.2	0.032	17.1±9.6	14.6±6.6	0.320	11.2±2.6	17.1±9.3	0.011	16.9±9.2	12.0±4.9	0.071	15.9±9.4	17.1±8.7	0.201
n	103	17		59	61		12	108		111	9		59	61
Wide stand, eyes closed
Length of sway (mm)	804.4±539.4	1194.1 ±603.6	0.005	873.2 ±574.3	812.7 ±530.0	0.763	517.0 ±218.4	897.6 ±577.1	0.008	860.2 ±523.1	851.3 ±976.3	0.220	737.4 ±518.0	977.7 ±583.5	0.002
Area of sway (mm^2)	790.8 ±1001.0	990.9 ±849.0	0.048	818.6 ±997.8	821.0 ±935.0	0.895	517.0 ±218.4	873.3 ±577.1	0.054	811.4 ±960.7	514.9 ±1260.7	0.976	692.6 ±1031.9	941.6 ±919.4	0.005
Mean speed (mm/s)	26.9±16.5	40.2±21.6	0.006	29.5 ±18.3	26.4 ±16.1	0.536	18.1±7.4	30.0 ±18.3	0.015	28.9 ±17.3	27.0 ±24.7	0.317	25.4 ±17.2	32.4 ±17.8	0.005
n	100	17		58	59		10	105		108	9		58	59
Narrow stand, eyes open
Length of sway (mm)	697.0±369.0	939.3 ±479.5	0.011	740.9 ±385.0	698.9 ±434.6	0.353	589.2 ±114.4	748.6 ±411.3	0.483	748.9 ±403.2	532.1 ±170.0	0.102	695.1 ±391.4	768.7 ±396.6	0.151
Area of sway (mm^2)	587.8±642.3	684.9 ±582.4	0.448	573.2 ±444.1	713.1 ±1101.1	0.606	424.9 ±156.0	622.1 ±663.0	0.574	616.7 ±654.2	424.3 ±194.8	0.533	618.4 ±755.4	585.7 ±488.6	0.970
Mean speed (mm/s)	23.5±12.2	32.6±18.6	0.011	25.2 ±13.3	23.2 ±14.8	0.188	20.8±4.6	25.3 ±14.2	0.657	25.3 ±13.9	18.8±7.2	0.133	24.0 ±14.2	25.6 ±13.1	0.340
n	75	14		49	40		10	79		81	8		49	40
Narrow stand, eyes closed
Length of sway (mm)	2507.4 ±1377.4	3209.0 ±1090.3	0.022	2696.1 ±1404,5	2260.2 ±1069.2	0.271	2154.3 ±524.8	2676.4 ±1417.7	0.541	2550.7 ±1190.6	3296.9 ±2513.2	0.528	2411.5 ±1183,2	2870.4 ±1571.6	0.123
Area of sway (mm^2)	1719.0 ±1592.1	1995.3 ±1165.8	0.120	1850.3 ±1632.6	1361.9 ±860.1	0.189	1286.9 ±362.8	1822.7 ±1610.9	0.668	1658.7 ±1358.3	2813.4 ±2641.4	0.315	1849.1 ±1473.5	1849.1 ±1473.5	0.339
Mean speed (mm/s)	42.1±21.0	54.9±18.6	0.014	45.7 ±21.7	37.2 ±16.5	0.171	37.6±9.1	45.0 ±22.0	0.541	43.1 ±19.2	54.8 ±35.0	0.482	41.7 ±19.8	47.1 ±22.4	0.205

Notes: Values are: mean, ± SD = standard deviation and number of patients (n); MMSE = Mini-Mental State Examination at hospital discharge (range 0–30), GDS = Geriatric Depression Scale at hospital discharge (range 1–15), Barthel index = Hamburger Classification Manual for the Barthel index in geriatrics at hospital discharge (range 0–100); TUG = Timed Up & Go at hospital discharge; P-values for Mann–Whitney U-Test, a two-tailed P value <0.05 were considered statistically significant.

Abbreviation: CIRS, Cumulative Illness Rating Scale.

Table 8 Force Plate Variables and Risk Factors for Frailty Part 2

Force Plate Variables	History of a Fall			History of Diabetes Mellitus			History of Stroke			Abnormal Muscle Strength			Visus (Median=50%)
	No	Yes	P	No	Yes	P	No	Yes	P	No	Yes	P	≥ 50%	< 50%	P
	Mean ± SD			Mean ± SD			Mean ± SD			Mean ± SD			Mean ± SD
n	46	77		87	36		105	18		58	65		70	53
Wide stand, eyes open
Length of sway (mm)	433.0±223.3	526.8 ±278.2	0.052	485.9 ±278.2	506.0 ±221.4	0.245	499.5 ±271.4	446.9 ±200.0	0.753	411.2 ±208.7	563.6 ±284.7	<0.001	405.5 ±176.6	605.7 ±310.7	<0.001
Area of sway (mm^2)	269.7±193.9	380.5 ±403.6	0.079	339.1 ±384.5	339.2 ±221.2	0.475	340.6 ±357.7	330.3 ±256.5	0.946	277.0 ±219.5	394.5 ±419.4	0.016	268.7 ±201.9	432.1 ±455.9	0.004
Mean speed (mm/s)	14.7±8.3	17.6±9.3	0.038	16.5±9.9	16.5±6.7	0.356	16.6±9.2	15.9±8.0	0.971	13.8±6.7	18.9 ±10.2	<0.001	13.5±5.6	20.5±11.0	<0.001
n	46	74		85	35		102	18		58	62		69	51
Wide stand, eyes closed
Length of sway (mm)	707.1±412.5	954.3 ±622.0	0.036	794.2 ±515.4	1018.4 ±645.4	0.034	868.2 ±508.2	810.9 ±464.7	0.994	739.4 ±537.1	972.0 ±567.7	0.004	767.6 ±541.9	984.0 ±572.4	0.011
Area of sway (mm^2)	532.7±486.8	997.2 ±1155.9	0.013	700.2 ±914.2	1108.1 ±1084.7	0.018	852.7 ±1035.1	629.1 ±561.1	0.564	746.1 ±957.7	887.4 ±1003.7	0.038	741.6 ±910.7	924.1 ±1067.3	0.114
Mean speed (mm/s)	23.6±13.9	32.0 ±19.3	0.014	27.2±17.9	32.5 ±17.4	0.042	28.8±18.1	28.3 ±16.3	0.857	24.9±16.5	32.4 ±18.4	0.005	25.1±15.4	33.8±19.7	0.008
n	45	72		83	34		99	18		56	61		68	49
Narrow stand, eyes open
Length of sway (mm)	638.4±355.7	790.1 ±407.7	0.018	718.6 ±403.8	765.5 ±372.0	0.265	729.8 ±397.1	745.7 ±387.5	0.850	608.2 ±319.7	846.1 ±423.0	<0.001	619.9 ±262.1	888.1 ±486.5	0.002
Area of sway (mm^2)	434.9±316.9	706.3 ±750.1	0.004	579.8 ±680.3	655.9 ±501.8	0.101	583.3 ±645.5	704.2 ±561.1	0.231	539.7 ±762.8	659.0 ±482.9	0.013	470.5 ±348.1	784.3 ±859.8	0.013
Mean speed (mm/s)	21.6±13.5	26.8 ±13.4	0.010	24.5±14.2	25.6 ±12.2	0.325	24.5±13.7	26.4 ±13.1	0.478	20.7±10.7	28.5 ±15.0	<0.001	20.9±8.5	30.2±17.2	0.001
n	37	52		69	20		75	14		47	42		54	35
Narrow stand, eyes closed
Length of sway (mm)	2266.4 ±1000.8	2867.8 ±1519.7	0.049	2441.3 ±1180.4	3226.4 ±1737.6	0.036	2618.1 ±1369.7	2615.9 ±1325.3	0.901	2378.4 ±1400.2	2885.6 ±1266.6	0.016	2456.4 ±1439.1	2866.6 ±1192.2	0.034
Area of sway (mm^2)	1385.2 ±909.7	2030.9 ±1811.4	0.053	1488.6 ±1069.6	2707.4 ±2354.2	0.014	1746.3 ±1411.1	1849.4 ±2124.3	0.752	1536.1 ±1240.6	2015.8 ±1783.1	0.340	1585.3 ±1303.4	2035.9 ±1813.3	0.118
Mean speed (mm/s)	39.9±18.2	47.9 ±22.3	0.046	41.7±19.7	52.6 ±23.9	0.037	44.0±21.3	45.2 ±20.6	0.693	39.6±19.5	49.3 ±21.7	0.018	40.7±20.0	49.5±20.3	0.018

Notes: Values are: mean, ± SD = standard deviation and number of patients (n); P-values for Mann–Whitney U-Test, a two-tailed P value <0.05 were considered statistically significant.

Table 9 Correlation Between Force Plate Variables and Risk Factors for Frailty

Force plate variables	MMSE			GDS			Barthel index			TUG			CIRS			Visus
	r	P-value	n	r	P-value	n	r	P-value	n	r	P-value	n	r	P-value	n	r	P-value	n
Wide stand, eyes open			123			123			123			123			123			123
Length of sway (mm)	−0.22	0.017		−0.12	0.195		−0.22	0.015		0.15	0.103		0.22	0.014		−0.31	0.001
Area of sway (mm^2)	−16.	0.079		−0.03	0.713		−0.19	0.035		0.13	0.139		0.11	0.244		−0.26	0.003
Mean speed (mm/s)	−0.20	0.029		−0.15	0.101		−0.22	0.016		0.15	0.091		0.19	0.037		−0.30	0.001
Wide stand, eyes closed			120			120			120			120			120			120
Length of sway (mm)	−0.23	0.013		−0.08	0.364		−0.17	0.065		0.12	0.212		0.27	0.003		−0.13	0.169
Area of sway (mm^2)	−0.13	0.166		−0.03	0.715		−0.13	0.161		0.10	0.290		0.22	0.017		−0.08	0.361
Mean speed (mm/s)	−0.21	0.021		−0.10	0.262		−0.16	0.082		0.12	0.202		0.25	0.006		−0.13	0.175
Narrow stand, eyes open			117			117			117			117			117			117
Length of sway (mm)	−0.28	0.002		−0.09	0.364		−0.13	0.179		0.14	0.131		0.16	0.085		−0.24	0.010
Area of sway (mm^2)	−0.16	0.077		−0.04	0.663		−0.14	0.122		0.20	0.035		0.08	0.424		−0.25	0.007
Mean speed (mm/s)	−0.73	0.004		−0.11	0.253		−0.12	0.212		0.16	0.088		0.13	0.175		−0.24	0.010
Narrow stand, eyes closed			98			89			89			89			89			89
Length of sway (mm)	−0.28	0.009		−0.14	0.191		−0.07	0.524		−0.05	0.625		0.19	0.082		−0.19	0.072
Area of sway (mm^2)	−0.16	0.129		−0.10	0.368		−0.14	0.200		0.01	0.913		0.10	0.344		−0.18	0.094
Mean speed (mm/s)	−0.29	0.006		−0.15	0.150		−0.07	0.511		−0.03	0.804		0.16	0.142		−0.21	0.044

Notes: Values are: number of patients (n); MMSE = Mini-Mental State Examination at hospital discharge (range 0–30), GDS = Geriatric Depression Scale at hospital discharge (range 1–15), Barthel index = Hamburger Classification Manual for the Barthel Index in geriatrics at hospital discharge (range 0–100); TUG = Timed Up & Go at hospital discharge; CIRS = Cumulative Illness Rating Scale; Visus = visual acuity (Distance 5 m), r = Spearman (bivariate correlation), a two-tailed P value <0.05 was considered statistically significant.