J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 11, Number 12, December 2019, pages 834-841

Skeletal Muscle Index at Intensive Care Unit Admission Is a Predictor of Intensive Care Unit-Acquired Weakness in Patients With Sepsis

Figure 1. Study flowchart. MV: mechanical ventilator; ICU-AW: intensive care unit-acquired weakness; MRC: Medical Research Council.

Figure 3. ROC curves for SMI at ICU admission in prediction of ICU-AW (n = 31). ROC: receiver operating characteristic; SMI: skeletal muscle index; ICU-AW: intensive care unit-acquired weakness. The ROC analysis identified a cut-off point of 44.1 cm²/m² (area under the curve: 0.745; sensitivity 78.3%; specificity 25.0%; P = 0.042).

**Table 1.** Comparison of Baseline Characteristics Between Groups With and Without ICU-AW
	Group AW (n = 23)	Group NAW (n = 8)	P value
Data are expressed as means ± standard deviation. Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. BMI: body mass index; APACHE: Acute Physiology and Chronic Health Evaluation; ICU-AW: AW: acquired weakness; NAW: non-acquired weakness.
Age (years)	66.0 ± 11.9	66.1 ± 13.3	0.511
Gender, male (%)	7 (30.4%)	6 (75.0%)	0.043
BMI (kg/m²)	24.5 ± 5.0	24.3 ± 1.9	< 0.999
Height	155.7 ± 11.9	162.0 ± 13.1	0.182
Weight (kg)	63.1 ± 14.7	59.6 ± 14.2	0.443
Barthel index	13.0 ± 19.6	16.2 ± 16.6	0.305
APACHE II score	22.8 ± 8.8	17.8 ± 4.1	0.167

Table 1. Comparison of Baseline Characteristics Between Groups With and Without ICU-AW

Group AW (n = 23)

Group NAW (n = 8)

P value

Data are expressed as means ± standard deviation. Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. BMI: body mass index; APACHE: Acute Physiology and Chronic Health Evaluation; ICU-AW: AW: acquired weakness; NAW: non-acquired weakness.

Age (years)

66.0 ± 11.9

66.1 ± 13.3

0.511

Gender, male (%)

7 (30.4%)

6 (75.0%)

0.043

BMI (kg/m²)

24.5 ± 5.0

24.3 ± 1.9

< 0.999

Height

155.7 ± 11.9

162.0 ± 13.1

0.182

Weight (kg)

63.1 ± 14.7

59.6 ± 14.2

0.443

Barthel index

13.0 ± 19.6

16.2 ± 16.6

0.305

APACHE II score

22.8 ± 8.8

17.8 ± 4.1

0.167

**Table 2.** Comparison of Laboratory Parameters Between Groups With and Without ICU-AW at ICU Admission and ICU Discharge
	ICU admission	ICU discharge
Data are expressed as means ± standard deviation. Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. Alb: serum albumin; BUN: blood urea nitrogen; Cre: creatinine; CRP: C-reactive protein; AST: aspartate aminotransferase; ALT: alanine aminotransferase; T-bil: total bilirubin; CK: creatine kinase; WBC: white blood cell count; ICU-AW: intensive care unit-acquired weakness; AW: acquired weakness; NAW: non-acquired weakness.
Alb (g/dL)	2.08 ± 0.4	1.9 ± 0.4	0.496	2.1 ± 0.4	2.1 ± 0.3	0.602
BUN (mg/dL)	44.4 ± 18.6	45.0 ± 29.0	0.769	28.5 ± 22.5	16.6 ± 5.8	0.09
Cre (mg/dL)	1.9 ± 1.3	2.9 ± 2.7	0.892	1.1 ± 1.4	0.6 ± 0.3	0.391
CRP (mg/dL)	24.5 ± 9.6	24.1 ± 6.8	0.964	8.7 ± 7.9	8.7 ± 7.9	0.964
Glucose (mg/dL)	155.3 ± 108.9	142.5 ± 57.3	0.701	121.2 ± 28.7	136 ± 30.2	0.13
Lactate (mg/dL)	4.2 ± 3.2	3.1 ± 1.6	0.54	1.3 ± 0.7	1.1 ±0.1	0.329
AST (U/L)	349.1 ± 925.9	132.7 ± 185.2	0.857	31.3 ± 21.3	42.7 ± 24	0.175
ALT(U/L)	248.2 ± 763.8	60.5 ± 71.1	0.786	33.6 ± 35.3	52.7 ± 38.5	0.114
T-bil (mg/dL)	1.54 ± 1.2	1.8 ± 1.1	0.442	0.9 ± 1	1 ± 0.7	0.275
CK (U/L)	887.3 ± 1435.6	1117.1 ± 1733.6	0.685	47.3 ± 80.1	101 ± 134.1	0.175
WBC (10³/µL)	9536.5 ± 7131.5	8405.0 ± 6932.1	0.498	9536.5 ± 7131.5	8405 ± 6932.1	0.391
PO₂ (mm Hg +)	121 ± 117.0	83.3 ± 19.2	0.542	82.2 ± 15	83.2 ± 13	0.769
pH	7.4 ± 0.1	7.4 ± 0.1	0.557	7.4 ± 0	7.4 ± 0	0.701
PCO₂ (mm Hg +)	31.4 ± 6.7	30.7 ± 7.9	0.874	39.4 ± 7.9	36.2 ± 5.5	0.404

Table 2. Comparison of Laboratory Parameters Between Groups With and Without ICU-AW at ICU Admission and ICU Discharge

ICU admission

ICU discharge

Group AW (n = 23)

Group NAW (n = 8)

P value

Group AW (n = 23)

Group NAW (n = 8)

P value

Data are expressed as means ± standard deviation. Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. Alb: serum albumin; BUN: blood urea nitrogen; Cre: creatinine; CRP: C-reactive protein; AST: aspartate aminotransferase; ALT: alanine aminotransferase; T-bil: total bilirubin; CK: creatine kinase; WBC: white blood cell count; ICU-AW: intensive care unit-acquired weakness; AW: acquired weakness; NAW: non-acquired weakness.

Alb (g/dL)

2.08 ± 0.4

1.9 ± 0.4

0.496

2.1 ± 0.4

2.1 ± 0.3

0.602

BUN (mg/dL)

44.4 ± 18.6

45.0 ± 29.0

0.769

28.5 ± 22.5

16.6 ± 5.8

0.09

Cre (mg/dL)

1.9 ± 1.3

2.9 ± 2.7

0.892

1.1 ± 1.4

0.6 ± 0.3

0.391

CRP (mg/dL)

24.5 ± 9.6

24.1 ± 6.8

0.964

8.7 ± 7.9

0.964

Glucose (mg/dL)

155.3 ± 108.9

142.5 ± 57.3

0.701

121.2 ± 28.7

136 ± 30.2

0.13

Lactate (mg/dL)

4.2 ± 3.2

3.1 ± 1.6

0.54

1.3 ± 0.7

1.1 ±0.1

0.329

AST (U/L)

349.1 ± 925.9

132.7 ± 185.2

0.857

31.3 ± 21.3

42.7 ± 24

0.175

ALT(U/L)

248.2 ± 763.8

60.5 ± 71.1

0.786

33.6 ± 35.3

52.7 ± 38.5

0.114

T-bil (mg/dL)

1.54 ± 1.2

1.8 ± 1.1

0.442

0.9 ± 1

1 ± 0.7

0.275

CK (U/L)

887.3 ± 1435.6

1117.1 ± 1733.6

0.685

47.3 ± 80.1

101 ± 134.1

0.175

WBC (10³/µL)

9536.5 ± 7131.5

8405.0 ± 6932.1

0.498

9536.5 ± 7131.5

8405 ± 6932.1

0.391

PO₂ (mm Hg +)

121 ± 117.0

83.3 ± 19.2

0.542

82.2 ± 15

83.2 ± 13

0.769

7.4 ± 0.1

0.557

7.4 ± 0

0.701

PCO₂ (mm Hg +)

31.4 ± 6.7

30.7 ± 7.9

0.874

39.4 ± 7.9

36.2 ± 5.5

0.404

**Table 3.** Factors Associated With ICU Discharge and Hospital Discharge
	Group AW (n = 23)	Group NAW (n = 8)	P value
Data are expressed as means ± standard deviation or as n (%). Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. BMI: body mass index; ICU LOS: intensive care unit length of stay; MV: mechanical ventilation; AW: acquired weakness; NAW: non-acquired weakness.
BMI	23.3 ± 5.4	22.8 ± 2.1	0.874
ICU LOS (day)	23.4 ± 20.6	11.8 ± 8.3	0.214
Hospital LOS (day)	95.5 ± 61.9	32.3 ± 14.1	0.007
Days until first upright sitting (day)	25.4 ± 35.6	8.8 ± 8	0.015
Days until first sitting in a wheelchair (day)	26.2 ± 27.2	9.2 ± 7.9	0.007
Blood purification therapy (%)	7 (30.4%)	1 (12.5%)	0.642
Barthel index	49.7 ± 33.3	81.2 ± 21.1	0.021
MV day	5.9 ± 7.5	2.6 ± 2.2	0.243

Table 3. Factors Associated With ICU Discharge and Hospital Discharge

Group AW (n = 23)

Group NAW (n = 8)

P value

Data are expressed as means ± standard deviation or as n (%). Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. BMI: body mass index; ICU LOS: intensive care unit length of stay; MV: mechanical ventilation; AW: acquired weakness; NAW: non-acquired weakness.

BMI

23.3 ± 5.4

22.8 ± 2.1

0.874

ICU LOS (day)

23.4 ± 20.6

11.8 ± 8.3

0.214

Hospital LOS (day)

95.5 ± 61.9

32.3 ± 14.1

0.007

Days until first upright sitting (day)

25.4 ± 35.6

8.8 ± 8

0.015

Days until first sitting in a wheelchair (day)

26.2 ± 27.2

9.2 ± 7.9

0.007

Blood purification therapy (%)

7 (30.4%)

1 (12.5%)

0.642

Barthel index

49.7 ± 33.3

81.2 ± 21.1

0.021

MV day

5.9 ± 7.5

2.6 ± 2.2

0.243

**Table 4.** Assessment of Skeletal Muscle Index
	ICU admission	ICU discharge
Data are expressed as means ± standard deviation. Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. CT: computed tomography; SMI: skeletal muscle index; ICU: intensive care unit; AW: acquired weakness; NAW: non-acquired weakness.
Days until CT imaging	0.5 ± 1.3	1.3 ± 2.5	0.241	18.1 ± 11.8	14.3 ± 5.7	0.825
SMI	40.7 ± 9.4	46.4 ± 6.4	0.042	36.9 ± 6.4	43.4 ± 4.1	0.029

Table 4. Assessment of Skeletal Muscle Index

ICU admission

ICU discharge

Group AW (n = 23)

Group NAW (n = 8)

P value

Group AW (n = 23)

Group NAW (n = 8)

P value

Data are expressed as means ± standard deviation. Categorical variables were compared using Fisher’s exact test, and continuous variables were compared using the Mann-Whitney U test. CT: computed tomography; SMI: skeletal muscle index; ICU: intensive care unit; AW: acquired weakness; NAW: non-acquired weakness.

Days until CT imaging

0.5 ± 1.3

1.3 ± 2.5

0.241

18.1 ± 11.8

14.3 ± 5.7

0.825

SMI

40.7 ± 9.4

46.4 ± 6.4

0.042

36.9 ± 6.4

43.4 ± 4.1

0.029

**Table 5.** Comparison of Skeletal Muscle Index With ICU-AW
	Lower SMI (n = 20)	Higher SMI (n = 11)	P value
Data are expressed as n (%). P < 0.05 was considered significant. Categorical variables were compared by Fisher’s exact test. ICU-AW: intensive care unit-acquired weakness; SMI: skeletal muscle index.
ICU-AW +	18 (58.0)	5 (16.1)	0.012
ICU-AW -	2 (6.4)	6 (19.3)

Table 5. Comparison of Skeletal Muscle Index With ICU-AW

Lower SMI (n = 20)

Higher SMI (n = 11)

P value

Data are expressed as n (%). P < 0.05 was considered significant. Categorical variables were compared by Fisher’s exact test. ICU-AW: intensive care unit-acquired weakness; SMI: skeletal muscle index.

ICU-AW +

18 (58.0)

5 (16.1)

0.012

ICU-AW -

2 (6.4)

6 (19.3)

**Table 6.** Logistic Regression Analysis of Variables Associated With Skeletal Muscle Index
Variable	OR (95% CI)	P value	Percentage of correct classifications
Data were analyzed by logistic regression analysis model. OR: odds ratio; CI: confidence interval; SMI: skeletal muscle index; ICU: intensive care unit.
SMI at ICU admission
> 44.1 cm²/m²	1.000
≤ 44.1 cm²/m²	10.800 (1.644 - 70.934)	0.013	77.4%

Table 6. Logistic Regression Analysis of Variables Associated With Skeletal Muscle Index

Variable

OR (95% CI)

P value

Percentage of correct classifications

Data were analyzed by logistic regression analysis model. OR: odds ratio; CI: confidence interval; SMI: skeletal muscle index; ICU: intensive care unit.

SMI at ICU admission

> 44.1 cm²/m²

1.000

≤ 44.1 cm²/m²

10.800 (1.644 - 70.934)

0.013

77.4%