Table 2.

Area under the receiver operating characteristic curve and Youden’s index for slowness (walk speed < 0.80 m/sec) according to measures of body anthropometry, DXA lean mass and grip strength in men and women.

	Men			Women
Variable	Area under the curve	Youden’s Index	Optimal cutpoint from Youden	Area under the curve	Youden’s Index	Optimal cutpoint from Youden
Age, yrs	0.68	0.13	78.90	0.61	0.33	79.00
Body mass index (BMI), kg/m2	0.68	0.10	30.06	0.64	0.30	27.55
Total body fat (TBF), kg	0.68	0.09	23.72	0.64	0.32	30.21
Appendicular fat mass (AFM), kg	0.69	0.10	9.53	0.64	0.33	15.93
Arm lean mass (ARMLM), kg	0.69	0.10	5.80	0.63	0.32	4.71
Appendicular lean mass (ALM)
ALM, kg	0.70	0.10	22.36	0.62	0.31	18.01
ALM/Height, kg/m	0.69	0.10	13.04	0.63	0.32	11.55
ALM/BMI, kg/kg/m2	0.73	0.10	0.84	0.62	0.30	0.56
ALM/TBF, kg/kg	0.68	0.10	1.02	0.61	0.30	0.55
ALM/Weight, kg/kg	0.69	0.11	0.28	0.61	0.30	0.24
ALM/Height2, kg/m2	0.68	0.10	7.44	0.63	0.31	7.14
ALM/Body Surface Area, kg/m2	0.69	0.10	11.64	0.61	0.30	10.45
ALM/Percent Fat, kg/%	0.71	0.11	0.80	0.61	0.29	0.50
ALM/AFM, kg/kg	0.69	0.10	2.75	0.61	0.30	1.27
Leg lean mass (LLM)
LLM, kg	0.70	0.10	16.09	0.62	0.31	13.27
LLM/Weight, kg/kg	0.69	0.10	0.21	0.62	0.29	0.18
LLM/Height, kg/m	0.69	0.09	9.71	0.62	0.30	8.22
LLM/ Height2, kg/m2	0.68	0.10	5.52	0.63	0.32	5.53
LLM/BMI, kg/kg/m2	0.73	0.10	0.62	0.62	0.31	0.41
LLM/TBF, kg/kg	0.69	0.10	0.72	0.61	0.30	0.43
LLM/Body Surface Area, kg/m2	0.70	0.10	8.66	0.61	0.29	7.98
Maximum grip strength (GR)
GR, kg	0.76	0.12	34.00	0.63	0.32	19.00
GS/ALM, kg/kg	0.73	0.10	1.60	0.65	0.29	1.36
GR/weight, kg/kg	0.74	0.11	0.45	0.66	0.30	0.34
GR/BMI, kg/kg/m2	0.76	0.11	1.33	0.67	0.31	0.78
GR/Height, kg/m	0.75	0.08	22.00	0.63	0.30	13.13
GR/Height2, kg/m2	0.74	0.10	12.13	0.63	0.31	8.25
GR/TBF, kg/kg	0.71	0.11	1.66	0.64	0.31	0.82
GR/Body Surface Area, kg/m2	0.75	0.11	18.70	0.65	0.30	12.82
GR/LLM, kg/kg	0.72	0.10	2.17	0.64	0.29	1.81
GR/Percent fat, kg/%	0.75	0.11	1.31	0.64	0.30	0.57
GR/AFM, kg/kg	0.72	0.12	3.98	0.64	0.33	1.44
GR/ARMLM, kg/kg	0.73	0.09	6.08	0.65	0.30	5.37

Full abbreviations are defined in supplemental table S3. Variable units are presented without cancellation for clarity. The Youden index is a global test accuracy performance— it ranges from 0 (poor diagnostic accuracy) to 1.0 (perfect accuracy) ²⁴. The optimal cut-point represents the value that optimizes both sensitivity and specificity. Note: Youden’s index for body weight and height were not calculated due to their overlap with body mass index.