3.1. Patients characteristics
The characteristics of included patients were presented in Table 1. A total of 247 older patients undergoing gastrointestinal tumor surgery were included in this study, 163 of them were men. 98 patients were diagnosed with gastric cancer and the rest with colorectal cancer. Their average age was about 75.5 and their average BMI was around 22.2kg/m2. 52 patients had history of alcohol and 60 patients had history of tobacco and most of them were male. 60 patients had history of abdominal surgery. The mean values of leukocyte, hemoglobin, albumin and NLR were within the range of normal clinical values. Most of the patients were in TNM stage I and II, but only 13 patients were defined as well differentiated histologic type.
Using the ImageJ software, we calculated the parameters of human body composition. SMI, SFI, VFI and VSR were 45.6±9.8cm2/m2, 32.1±18.7cm2/m2, 49.6±42.0cm2/m2, 1.69±0.75 in men, 36.9±8.6cm2/m2, 51.9±28.0cm2/m2, 49.0±27.4cm2/m2, 0.99±0.42 in women.
Table 1: Overall characteristics of patients.
|
Men(n=163)
|
Women(n=84)
|
Total(n=247)
|
Age(years)
|
75.34(4.70)
|
75.79(5.01)
|
75.5(4.8)
|
Cancer site, n(%)
|
|
|
|
gastric
|
77(31.1)
|
21(8.5)
|
98(39.7)
|
colorectal
|
86(34.8)
|
63(25.5)
|
149(60.3)
|
BMI(kg/m2)
|
22.5(3.2)
|
21.9(3.3)
|
22.2(3.2)
|
Charlson comorbidity index
|
4(1)
|
4(2)
|
4(2)
|
History of alcohol, n(%)
|
48(19.4)
|
4(1.6)
|
52(21.1)
|
History of tobacco, n(%)
|
67(27.1)
|
1(0.4)
|
68(27.5)
|
History of abdominal surgery, n(%)
|
34(13.7)
|
26(10.5)
|
60(24.3)
|
Major laboratory indicators
|
|
|
|
Leukocyte(×10^9/L)
|
5.6(2.2)
|
5.9(2.2)
|
5.7(2.1)
|
Hemoglobin(g/L)
|
131.0(31.0)
|
120.0(29.8)
|
126.5(32.0)
|
Albumin(g/L)
|
41.5(7.1)
|
42.7(5.6)
|
42.1(6.7)
|
NLR
|
2.5(1.4)
|
2.1(1.6)
|
2.4(1.5)
|
Intraoperative blood loss(ml)
|
123.4(92.8)
|
103.8(80.1)
|
116.3(89.0)
|
Duration of operation(min)
|
195(67)
|
174(55)
|
188(65)
|
Cancer stage, n(%)
|
|
|
|
Ⅰ
|
70(28.3)
|
28(11.3)
|
98(39.7)
|
Ⅱ
|
57(23.1)
|
26(10.5)
|
83(33.6)
|
Ⅲ
|
36(14.6)
|
30(12.1)
|
66(26.7)
|
Histologic type, n(%)
|
|
|
|
Poorly differentiated
|
66(26.7)
|
33(13.4)
|
99(40.1)
|
Moderately differentiated
|
90(36.4)
|
46(18.6)
|
136(55.1)
|
Well differentiated
|
7(2.8)
|
6(2.4)
|
13(5.3)
|
Body composition
|
|
|
|
SMI(cm2/m2)
|
45.6(9.8)
|
36.9(8.6)
|
42.6(10.9)
|
SFI(cm2/m2)
|
32.1(18.7)
|
51.9(28.0)
|
37.6(24.3)
|
VFI(cm2/m2)
|
49.6(42.0)
|
49.0(27.4)
|
49.4(35.7)
|
VSR
|
1.69(0.75)
|
0.99(0.42)
|
1.45(0.77)
|
Postoperative complication, n(%)
|
37(15.0)
|
28(11.3)
|
65(26.3)
|
Length of stay(day)
|
10(4)
|
9(4)
|
9(5)
|
Abbreviations: BMI= body mass index; NLR= neutrophil to lymphocyte ratio; SMI=skeletal muscle index; SFI= subcutaneous fat index; VFI= visceral fat index; VSR= visceral to subcutaneous ratio of fat area.
3.2. Factors associated with sarcopenia
71 patients were classified as sarcopenia. The incidence of sarcopenia in these patients with digestive tract tumors was about 28.7%.
This study detected several factors associated with sarcopenia as Table 2 showed. In univariate analysis, sarcopenia was associated with advanced age (p<0.001), lower BMI (p<0.001), lower hemoglobin (p=0.009), having history of abdominal surgery (p=0.010), and higher VFI (p<0.001). Higher BMI (p<0.001) and lower SFI (p=0.005) were protective factors for sarcopenia. Multivariate logistic regression was used to further analyse the data and it showed that having history of abdominal surgery (OR:2.5; 95% CI:1.3 to 5.3; p=0.007), advanced age (OR:3.0; 95% CI:1.6 to 5.7; p=0.001) and lower BMI (OR:3.4; 95% CI:1.3 to 8.6; p=0.011) were independent risk factors for sarcopenia.
Table 2: Univariate and multivariate logistic regression analysis of sarcopenia associated factors.
Variable
|
Univariate analysis
|
Multivariate analysis
|
|
OR
|
95%CI
|
p Value
|
OR
|
95%CI
|
p Value
|
Sexa
|
0.6
|
0.3-1.1
|
0.084
|
|
|
|
Ageb
|
3.2
|
1.8-5.8
|
<0.001
|
3
|
1.6-5.7
|
0.001
|
Cancer sitec
|
0.6
|
0.3-1.1
|
0.078
|
|
|
|
BMId
|
3.3
|
1.3-8.0
|
0.009
|
3.4
|
1.3-8.6
|
0.011
|
BMId*
|
0.2
|
0.1-0.4
|
<0.001
|
0.2
|
0.1-0.4
|
<0.001
|
Charlson comorbidity indexe
|
1.5
|
0.8-2.7
|
0.207
|
|
|
|
History of alcoholf
|
1.7
|
0.8-3.1
|
0.086
|
|
|
|
History of tobaccog
|
1.5
|
0.8-2.8
|
0.252
|
|
|
|
History of abdominal surgeryh
|
2.2
|
1.2-4.1
|
0.010
|
2.6
|
1.3-5.3
|
0.007
|
Leukocytei
|
1.4
|
0.8-2.4
|
0.254
|
|
|
|
Hemoglobinj
|
2.1
|
1.2-3.7
|
0.009
|
|
|
|
Albumink
|
1.7
|
0.9-2.9
|
0.075
|
|
|
|
NLRl
|
0.7
|
0.4-1.2
|
0.159
|
|
|
|
Cancer stagem
|
1.1
|
0.8-1.5
|
0.470
|
|
|
|
Histologic typen
|
1
|
0.6-1.7
|
0.860
|
|
|
|
SFIo
|
0.4
|
0.3-0.8
|
0.005
|
|
|
|
VFIp
|
2.9
|
1.6-5.3
|
<0.001
|
|
|
|
VSRq
|
1.0
|
0.6-1.7
|
0.985
|
|
|
|
a. Female as reference; b. age≤75 as reference; c. colorectal cancer as reference; d. BMI<18.5kg/m2 vs 18.5kg/m2≤BMI≤24kg/m2; d*. BMI>24kg/m2 vs 18.5kg/m2≤BMI≤24kg/m2; e. Charlson comorbidity index≤4 as reference; f. no history of alcohol as reference; g. no history of tobacco as reference; h. no history of abdominal surgery as reference; i. leukocyte≥5.7 as reference; j. hemoglobin≥126.5 as reference; k.albumin≥42.1 as reference; l. NLR≥2.4 as reference; m. stageⅡ and stageⅢ vs stageⅠ; n. moderately and well differentiated vs poorly differentiated; o. SFI≤37.6cm2/m2 as reference; p. VFI≤49.4cm2/m2 as reference; q. VSR≤1.45 as reference.
Abbreviations: OR= odds ratio; CI= confidence interval; BMI= body mass index; NLR= neutrophil to lymphocyte ratio; SMI=skeletal muscle index; SFI= subcutaneous fat index; VFI= visceral fat index; VSR= visceral to subcutaneous ratio of fat area.
3.3. Relationship between sarcopenia and postoperative complication
About 62 patients had grade two and above of Clavien-Dindo classification of surgical complications. The main complications included postoperative hemorrhage, pulmonary infection, abdominal infection, seroperitoneum, delirium, anastomotic leakage, ileus, venous thrombosis, heart failure, etc. Exploratory laparotomy was performed in four patients after operation because of the postoperative hemorrhage or ileus. One patient got interventional operation for multiple thrombosis. 1 patient died because of hemorrhoea. One patient discharged from hospital giving up treatment because of severe infection and bone marrow suppression.
Several factors were found associated with postoperative complications as Table 3 presented. In univariate analysis, advanced age (p=0.012), higher Charlson comorbidity index (p=0.014), and sarcopenia (p=0.001) were associated with postoperative complications. Further multivariate logistic regression analysis showed that sarcopenia (OR:2.6; 95% CI:1.4 to 4.9; p=0.002), and higher Charlson comorbidity index (OR:2.1; 95% CI:1.1 to 3.9; p=0.026) were independent risk factors of postoperative complications.
Table 3: Univariate and multivariate logistic regression analysis of postoperative complications associated factors.
Variable
|
Univariate analysis
|
Multivariate analysis
|
|
OR
|
95%CI
|
p Value
|
OR
|
95%CI
|
p Value
|
Sexa
|
1.4
|
0.8-2.6
|
0.226
|
|
|
|
Ageb
|
2.1
|
1.2-3.8
|
0.012
|
|
|
|
Cancer sitec
|
1.7
|
0.9-3.1
|
0.095
|
|
|
|
BMId
|
2.2
|
0.9-5.4
|
0.097
|
|
|
|
BMId*
|
0.8
|
0.4-1.6
|
0.618
|
|
|
|
Charlson comorbidity indexe
|
2.2
|
1.2-4.0
|
0.014
|
2.1
|
1.1-3.9
|
0.026
|
History of alcoholf
|
2.2
|
0.9-4.9
|
0.067
|
|
|
|
History of tobaccog
|
1.1
|
0.6-2.1
|
0.723
|
|
|
|
History of abdominal surgeryh
|
1.8
|
1.0-3.5
|
0.065
|
|
|
|
Leukocytei
|
1.3
|
0.7-2.3
|
0.400
|
|
|
|
Hemoglobinj
|
1.2
|
0.7-2.1
|
0.207
|
|
|
|
Albumink
|
0.9
|
0.5-1.7
|
0.851
|
|
|
|
NLRl
|
0.7
|
0.4-1.2
|
0.207
|
|
|
|
Cancer stagem
|
1.8
|
1.0-3.3
|
0.060
|
|
|
|
Histologic typen
|
1.2
|
0.7-1.9
|
0.510
|
|
|
|
Sarcopeniao
|
2.7
|
1.5-5.0
|
0.001
|
2.6
|
1.4-4.9
|
0.002
|
SFIp
|
0.8
|
0.5-1.4
|
0.442
|
|
|
|
VFIq
|
0.9
|
0.5-1.6
|
0.696
|
|
|
|
VSRr
|
1.4
|
0.8-2.4
|
0.288
|
|
|
|
Intraoperative blood losss
|
1.4
|
0.7-2.6
|
0.386
|
|
|
|
Duration of operationt
|
1.8
|
1.0-3.2
|
0.051
|
|
|
|
a. Female as reference; b. age≤75 as reference; c. colorectal cancer as reference; d. BMI<18.5kg/m2 vs 18.5kg/m2≤BMI≤24kg/m2; d*. BMI>24kg/m2 vs 18.5kg/m2≤BMI≤24kg/m2; e. Charlson comorbidity index≤4 as reference; f. no history of alcohol as reference; g. no history of tobacco as reference; h. no history of abdominal surgery as reference; i. leukocyte≥5.7 as reference; j. hemoglobin≥126.5 as reference; k. albumin≥42.1 as reference; l. NLR≥2.4 as reference; m. stageⅡ and stageⅢ vs stageⅠ; n. moderately and well differentiated vs poorly differentiated; o. without sarcopenia as reference; p. SFI≤37.6cm2/m2 as reference; q. VFI≤49.4cm2/m2 as reference; r. VSR≤1.45 as reference; s. blood loss≤116ml as reference ; t. time≤196min as reference.
Abbrebiation:OR= odds ratio; CI= confidence interval; BMI= body mass index; NLR= neutrophil to lymphocyte ratio; SMI=skeletal muscle index; SFI= subcutaneous fat index; VFI= visceral fat index; VSR= visceral to subcutaneous ratio of fat area.
3.4. Factors associated with length of stay
Linear regression was used to analyze the risk factors associated with length of stay. After the factors which were correlated with each other were excluded, it was found that Charlson comorbidity index (p=0.019), tumor site (p=0.016), and duration of surgery (p=0.045) were significantly correlated with length of hospital stay. Higher Charlson comorbidity index and longer operative time will result in longer hospital stays. The length of stay of patient with gastric cancer was significantly longer than those who with colorectal cancer.