Comparing the Performance of Calf Circumference, Albumin, and BMI for Predicting Mortality in Immobile Patients

Figures & data

Table 1 Subject Clinical Characteristics

Calf Circumference	Overall	CC≥31cm	CC<31cm	Standardize Diff.	P-value
N	387	264 (68.2%)	123 (31.8%)
Age (SD, years)	61.22 (15.18)	59.22 (14.66)	65.50 (15.44)	0.42 (0.20, 0.63)	<0.001
Albumin (SD, g/L)	35.38 (6.00)	35.98 (5.83)	34.15 (6.18)	0.30 (0.08, 0.53)	0.001
BMI (SD, kg/m^2)	23.98 (3.55)	24.92 (3.18)	21.96 (3.46)	0.89 (0.67, 1.11)	<0.001
Red blood cell (SD, 10^9/L)	3.91 (1.58)	3.93(0.75)	3.87(2.57)	0.03 (−0.19, 0.25)	0.746
Hemoglobin (g/L, SD)	115.90 (22.78)	118.74 (23.31)	109.98 (20.48)	0.40 (0.18, 0.62)	<0.001
White blood cell (SD,10^9/L)	9.66 (4.33)	9.60 (4.42)	9.77 (4.14)	0.04 (−0.18, 0.26)	0.549
Neutrophils (SD, 10^9/L)	7.57 (4.14)	7.44 (4.21)	7.83 (3.99)	0.09 (−0.12, 0.31)	0.286
Leukomonocyte (SD,10^9/L)	1.29 (0.92)	1.33 (1.01)	1.20 (0.69)	0.14 (−0.08, 0.36)	0.214
Fasting plasma glucose (SD, mmol/L)	6.85 (2.51)	6.74 (2.45)	7.10 (2.64)	0.14 (−0.11, 0.40)	0.101
Calf circumference (SD, cm)	32.57 (3.96)	34.49 (3.12)	28.46 (1.91)	2.33 (2.06, 2.60)	<0.001
Gender (n, %)				0.30 (0.08, 0.51)	0.007
Male	199 (51.42%)	148 (56.06%)	51 (41.46%)
Female	188 (48.58%)	116 (43.94%)	72 (58.54%)
Ethnicity (n, %)				0.10 (−0.11, 0.32)	0.372
Han	369 (66.24%)	250 (94.70%)	119 (96.75%)
Other	188 (33.76	14 (5.30%)	4 (3.25%)
Education (n, %)				0.45 (0.23, 0.66)	<0.001
Illiterate	49 (12.66%)	22 (8.33%)	27 (21.95%)
Primary	107 (27.65%)	69 (26.14%)	38 (30.89%)
Middle school and above	171 (44.19%)	129 (48.86%)	42 (34.15%)
College degree or above	60 (15.50%)	44 (16.67%)	16 (13.01%)
Bedsores (n, %)				0.16 (−0.05, 0.38)	0.158
No	369 (95.35%)	249 (94.32%)	120 (97.56%)
Yes	18 (4.65%)	15 (5.68%)	3 (2.44%)
Pneumonia (n, %)				0.40 (0.19, 0.62)	<0.001
No	311 (80.36%)	226 (85.61%)	85 (69.11%)
Yes	76 (19.64%)	38 (14.39%)	38 (30.89%)
Primary diagnosis (n, %)				0.25 (0.03,0.47)	0.377
Orthopedic disorders and fractures	116 (30.61%)	81 (31.40%)	35 (28.93%)
Cancer	29 (7.65%)	21 (8.14%)	8 (6.61%)
Stroke	41 (10.82%)	29 (11.24%)	12 (9.92%)
Hypertension and lung disease	30 (7.92%)	21 (8.14%)	9 (7.44%)
Phlebitis	83 (21.90%)	48 (18.60%)	35 (28.93%)
Other	80 (21.11%)	58 (22.48%)	22 (18.18%)
Urinary tract infection (n, %)				0.28 (0.07, 0.50)	0.003
No	376 (97.16%)	261 (98.86%)	115 (93.50%)
Yes	11 (2.84%)	3 (1.14%)	8 (6.50%)
Smoking (n, %)				0.02 (−0.19, 0.23)	0.982
Never	300 (77.52%)	204 (77.27%)	96 (78.05%)
Current	51 (13.18%)	35 (13.26%)	16 (13.01%)
Former	36 (9.30%)	25 (9.47%)	11 (8.94%)
Surgery (n, %)				0.13 (−0.09, 0.34)	0.248
No	166 (42.89%)	108 (40.91%)	58 (47.15%)
Yes	221 (57.11%)	156 (59.09%)	65 (52.85%)
Bed-rest days (IQR)	11.00 (5.00–18.50)	10.00 (5.00–17.00)	13.00(7.00–24.00)	0.27(0.06,0.49)	0.003
Charlson Comorbidity (n, %) Index				0.12 (−0.10, 0.33)	0.285
<2	266 (68.73%)	186 (70.45%)	80 (65.04%)
≥2	140 (36.18%)	78 (29.55%)	43 (34.96%)
Antibiotics (n, %)				0.23 (0.01,0.44)	0.045
No	94 (24.29%)	72 (27.27%)	22 (17.89%)
Yes	293 (75.71%)	192 (72.73%)	101 (82.11%)
Glucocorticoids (n, %)				0.31 (0.09,0.52)	0.004
No	247 (63.82%)	181 (68.56%)	66 (53.66%)
Yes	140 (36.27%)	83 (31.44%)	57 (46.34%)
90-day mortality (n, %)				0.35 (0.13, 0.56)	<0.001
No	366 (94.57%)	257 (97.35%)	109 (88.62%)
Yes	21 (5.43%)	7 (2.65%)	14 (11.38%)

Abbreviations: IQR, interquartile range; CC, calf circumference.

Table 2 Univariate Regression Analysis of the Variables Associated with 90-Day Mortality

	Statistics	90-Day Mortality	P-value
Gender (n, %)
Male	199 (51.42%)	1.0 Reference
Female	188 (48.58%)	1.17 (0.49, 2.83)	0.7202
Age	61.22 ± 15.18	1.07 (1.03, 1.11)	0.0004
Ethnicity (n, %)
Han	369 (95.35%)	1.0 Reference
Other	18 (4.65%)	1.03 (0.13, 8.11)	0.9802
Education (n, %)
Illiterate	49 (12.66%)	1.0 Reference
Primary	107 (27.65%)	0.43 (0.12, 1.57)	0.2011
Middle school and above	171 (44.19%)	0.49 (0.16, 1.53)	0.2197
College degree or above	60 (15.50%)	0.30 (0.06, 1.64)	0.1656
Primary diagnosis (n, %)
Orthopedic disorders and fractures	116 (30.61%)	1.0 reference
Cancer	29 (7.65%)	0.56 (0.07–4.71)	0.5903
Stroke	41 (10.82%)	0.39 (0.05–3.26)	0.3845
Hypertension and lung disease	30 (7.92%)	2.40 (0.65,8.80)	0.1881
Phlebitis	83 (21.90%)	0.79 (0.22–2.79)	0.7120
Other	80 (21.11%)	0.82 (0.23–2.90)	0.7574
Bedsores (n, %)
No	369 (95.35%)	1.0 Reference
Yes	18 (4.65%)	1.03 (0.13, 8.11)	0.9802
Pneumonia (n, %)
No	311 (80.36%)	1.0 Reference
Yes	76 (19.64%)	5.09 (2.08, 12.50)	0.0004
Urinary tract infection (n, %)
No	376 (97.16%)	1.0 Reference
Yes	11 (2.84%)	4.18 (0.84, 20.68)	0.0800
Albumin	35.38 ± 6.00	0.87 (0.80, 0.94)	0.0007
BMI (SD, kg/m^2)	23.98 ± 3.55	0.85 (0.74, 0.97)	0.0178
Red blood cell (SD, 10^9/L)	3.91 ± 1.58	0.71 (0.39, 1.30)	0.2674
Hemoglobin (g/L, SD)	115.90 ± 22.78	0.99 (0.97, 1.01)	0.3325
White blood cell (SD,10^9/L)	9.66 ± 4.33	1.03 (0.94, 1.14)	0.5088
Neutrophils (SD,10^9/L)	7.57 ± 4.14	1.07 (0.98, 1.18)	0.1431
Leukomonocyte (SD,10^9/L)	1.29 ± 0.92	0.13 (0.04, 0.41)	0.0006
Smoker (n, %)
Never	300 (77.52%)	1.0 Reference
Current	51 (13.18%)	0.78 (0.17, 3.50)	0.7407
Former	36 (9.30%)	2.37 (0.74, 7.59)	0.1445
Fasting plasma glucose	6.85 ± 2.51	1.24 (1.06, 1.46)	0.0073
Surgery (n, %)
No	166 (42.89%)	1.0 Reference
Yes	221 (57.11%)	0.22 (0.08, 0.61)	0.0035
CC (SD, cm)	32.57 ± 3.96	0.75 (0.66, 0.86)	<0.0001
CC (n, %)
≥31cm	264 (68.22%)	1.0 Reference
<31cm	123 (31.78%)	4.72 (1.85, 12.01)	0.0011
Bed-rest days (IQR)	11.00 (5.00–18.50)	1.02 (1.00, 1.04)	0.0549
Charlson Comorbidity Index (n, %) <2	266 (68.73%)	1.0 reference
≥ 2	121(31.27%)	7.95 (2.84, 22.27)	<0.0001
Antibiotics (n, %)
No	94 (24.29%)	1.0 Reference
Yes	293 (75.71%)	3.19 (0.73, 13.96)	0.1235
Glucocorticoids (n, %)
No	247 (63.82%)	1.0 Reference
Yes	142 (36.18%)	3.06(1.24, 7.57)	0.0157

Abbreviation: CC, calf circumference.

Table 3 Multivariate Regression Analysis Between Nutritional Status (CC, Albumin, and BMI) and Mortality in Different Models

Exposure	Non-Adjusted (OR, 95% CI)	P-value	Adjusted I (OR, 95% CI)	P-value	Adjusted II (OR, 95% CI)	P-value
BMI	0.85 (0.74, 0.97)	0.017	0.89 (0.78, 1.02)	0.088	0.89 (0.76, 1.05)	0.185
CC(1cm)	0.75 (0.65, 0.86)	<0.001	0.79 (0.68, 0.92)	0.002	0.79 (0.65, 0.96)	0.017
Albumin	0.86 (0.79, 0.94)	0.0006	0.86 (0.79, 0.95)	0.003	0.94 (0.83, 1.07)	0.390
CC (n, %)
≥31cm	1.0 Reference		1.0 Reference		1.0 Reference
<31cm	4.71 (1.85, 12.00)	0.001	3.59 (1.32, 9.74)	0.011	4.24 (1.07, 16.74)	0.038

Notes: Exposure: CC; CC category; albumin; BMI. Non-adjusted model. Adjusted I model adjusted for: age, gender, education. Adjusted II model adjusted for: age; gender; education; ethnicity; smoking; red blood cell; hemoglobin; white blood cell; neutrophils; leukomonocyte; pneumonia; urinary tract infection; surgery, antibiotics, glucocorticoids, Charlson Comorbidity Index.

Abbreviation: CC, calf circumference.

Figure 1 A nonlinear relationship between calf circumference and rate of 90-day mortality using a generalized additive model.

Table 4 Prediction Performance of Four Variables for Estimating 90-Day Mortality

	CC+Albumin	CC	Albumin	BMI
AUC (95% CI)	0.812 (0.733–0.890)	0.759 (0.662–0.856)	0.735 (0.638–0.833)	0.653 (0.538–0.767)
P-value (vs BMI)	0.001	0.033	0.250	-
Cutoff	−0.275	31.125	36.35	24.515
Sensitivity %	0.728	0.650	0.466	0.445
Specificity %	0.761	0.761	0.952	0.904
PPV	0.150	0.111	0.102	0.085
NPV	0.979	0.979	0.993	0.987
PLR	2.802	2.802	1.785	1.631
NLR	0.327	0.327	0.102	0.213

Abbreviation: CC, calf circumference.

Figure 2 The ROC curve analysis for various models, based on different variables: Model 1 for combined calf circumference and albumin (green); Model 2: for calf circumference (Blue); Model 3: for albumin (Black); Model 4: for BMI(Red).