Baseline data of patients
Baseline information and perioperative data of all 177 patients were listed in Table 1.The average age was 64, with 46 females (26%) and 131 males (74%).According to whether the patients had postoperative pneumonia, they were divided into the pneumonia group and the non-pneumonia group, of which 32 (18%) were in the pneumonia group.The results showed that patients with previous respiratory diseases were more likely to develop postoperative pneumonia (P < 0.05).Other data such as gender, age, BMI, comorbidities except respiratory diseases, neoadjuvant chemotherapy,length of hospital stay, ASA classification, surgical method, anesthesia intubation method, anastomotic site, intraoperative blood loss,fluid infusion, operative time, tumor location, length, and degree of differentiation were not statistically significant (P > 0.05).
Table 1 Demographic and clinical characteristics
Parameters
|
Postoperative pneumonia
|
P value
|
YES(n=32)
|
NO(n=145)
|
Gender,n (%)
Male
Female
|
|
P=0.140
|
27(84.4)
|
104(71.7)
|
-
|
5(15.6)
|
41(28.3)
|
-
|
Age(year)
|
65.5±8.4
|
63.7±8.0
|
P=0.259
|
BMI(kg/m2)
|
23.3±3.2
|
24.0±3.0
|
P=0.235
|
Comorbidities, n (%)
Hypertension
Cerebral infarction
Coronary heart disease
Respiratory diseases
Hepatitis
Diabetes
|
|
|
14(43.8)
|
47(32.4)
|
P=0.220
|
4(12.5)
|
14(14.7)
|
P=0.746
|
3(9.4)
|
19(13.1)
|
P=0.769
|
5(15.6)
|
4(2.8)
|
P=0.011
|
2(6.3)
|
4(2.8)
|
P=0.297
|
4(12.5)
|
19(13.1)
|
P=1.000
|
The history of drinking,n (%)
No
Yes
Smoking index
|
|
P=0.637
|
23(71.9)
|
98(67.6)
|
-
|
9(28.1)
|
47(32.4)
|
-
|
317±453.1
|
250.1±429.0
|
P=0.425
|
History of chest surgery,n (%)
|
1(3.1)
|
5(3.4)
|
P=1.000
|
The length of hospital stay(day)
|
18.3±8.1
|
17.3±5.4
|
P=0.895
|
Neoadjuvant chemotherapy,n (%)
Yes
No
|
|
P=0.071
|
13(40.6)
|
36(24.8)
|
|
19(59.4)
|
109(75.2)
|
|
ASA Grade,n (%)
Ⅰ
Ⅱ
Ⅲ
|
|
P=0.316
|
2(6.2)
|
2(1.4)
|
-
|
22(68.8)
|
125(86.2)
|
-
|
8(25.0)
|
18(12.4)
|
-
|
Surgical method,n (%)
MIE
Open
|
|
P=0.553
|
27(84.4)
|
142(97.9)
|
|
5(15.6)
|
3(2.1)
|
|
Intubation method,n (%)
Single
Double
|
|
P=1.000
|
1(3.1)
|
5(3.4)
|
-
|
31(96.9)
|
140(96.6)
|
-
|
Anastomotic site,n (%)
Neck
Chest
|
|
P=0.328
|
27(84.4)
|
132(91.0)
|
-
|
5(15.6)
|
13(9.0)
|
-
|
Blood loss(ml)
|
192.2±44.2
|
182.3±68.7
|
P=0.309
|
Intraoperative fluid utilization(ml)
|
2348.4±619.0
|
2303.5±664.5
|
P=0.715
|
Operative time(min)
|
317.4±77.6
|
362.3±70.0
|
P=0.546
|
Tumor location,n (%)
Upper
Middle
Lower
|
|
P=0.447
|
3(9.4)
|
11(7.6)
|
-
|
12(37.5)
|
72(49.7)
|
-
|
17(53.2)
|
62(42.8)
|
-
|
Tumor length(cm)
<3
≥3
|
|
P=0.975
|
14(43.8)
|
63(43.4)
|
-
|
18(56.3)
|
82(56.6)
|
-
|
Differentiation,n (%)
Low
Middle
High
|
|
P=0.159
|
7(21.9)
|
32(22.1)
|
-
|
23(71.9)
|
84(57.9)
|
-
|
2(6.3)
|
29(20)
|
-
|
Notes:P-values were calculated by Chi-square test, Fisher exact test, Mann-Whitney U or t test
Abbreviations:BMI Body mass index,Smoking index cigarettes/day×year,ASA American Society of Anesthesiologists
Laboratory tests data
Preoperative laboratory tests of patients with and without pneumonia were shown in Table 2. Creatinine, albumin, white blood cells, platelets, central granulophils, monocytes, fibrinogen, AFR, PLR were statistically different between the two groups (P < 0.05), and the P values of fibrinogen and AFR were < 0.001.
Table 2 Laboratory tests
Laboratory test
|
Postoperative pneumonia
|
P value
|
YES
|
NO
|
Creatinine(μmol/L)
|
76.3±16.2
|
71.28±16.3
|
P=0.037
|
Albumin(g/L)
|
39.1±5.1
|
41.8±3.3
|
P=0.005
|
Globulin(g/L)
|
26.8±4.8
|
25.5±4.3
|
P=0.151
|
WBC(×109/L)
|
7.2±3.1
|
5.8±1.8
|
P=0.018
|
Hemoglobin(g/L)
|
126.1±18.7
|
129.3±15.1
|
P=0.3
|
Platelet(×109)
|
230.3±58.4
|
200.4±6.6
|
P=0.016
|
Neutrophils(×109/L)
|
4.6±2.9
|
4.2±6.6
|
P=0.004
|
Lymphocyte(×109/L)
|
1.8±0.7
|
1.7±0.5
|
P=0.690
|
Monocytes(×109/L)
|
0.6±0.2
|
0.5±0.1
|
P=0.015
|
Fibrinogen(mg/dL)
|
3.9±0.8
|
3.2±0.7
|
P<0.001
|
AFR
|
10.6±3.2
|
13.6±3.0
|
P<0.001
|
NLR
|
3.1±2.8
|
2.7±3.7
|
P=0.1
|
PLR
|
144.6±56.4
|
126.8±58.8
|
P=0.048
|
MLR
|
0.72±2.1
|
0.3±0.2
|
P=0.103
|
Notes:P-values were calculated by Mann-Whitney U or t test
Abbreviations:WBC White blood cell,AFR Albumin-to-fibrinogen ratio,NLR Neutrophils-to-Lymphocyte ratio,PLR Platelet-to-Lymphocyte ratio,MLR Monocytes-Lymphocyte ratio
The predictive value of AFR for postoperative pneumonia
ROC curve analysis was used to assess the predictive value of AFR for postoperative pneumonia and the cut-off value of statistically significant laboratory test results.As shown in Figure 1, preoperative AFR level predicted postoperative pneumonia with an AUC area of 0.767, a sensitivity of 65.6%, and a specificity of 83.4%.The cut-off values of AFR, creatinine and albumin were obtained based on the Youden’s Index.Then, according to the cut-off value, all patients were divided into two groups: high level group and low level group.
Risk factors for postoperative pneumonia
All possible risk factors (P < 0.05) were included in univariate and multivariate logistic regression analysis.Variables with P < 0.1 in univariate analysis were included in multivariate analysis. Multivariate logistic regression analysis showed that low creatinine, albumin and high AFR levels were independent risk factors for postoperative pneumonia in patients after radical esophagectomy.
Table 3 Risk factors by univariate and multivariate logistic regression analyses
Variables
|
Univariate
|
Multivariate
|
OR(95%CI)
|
P value
|
OR(95%CI)
|
P value
|
Respiratory diseases (yes vs no)
|
1.646-25.889
|
0.008
|
|
|
Creatinine (high vs low)
|
1.219-6.499
|
0.015
|
0.081-0.712
|
0.01
|
Albumin (high vs low)
|
0.07-0.366
|
<0.001
|
1.268-11.656
|
0.017
|
WBC (high vs low)
|
1.678-8.190
|
0.001
|
|
|
Platelet(high vs low)
|
1.426-6.928
|
0.005
|
|
|
Neutrophils (high vs low)
|
1.906-12.633
|
0.001
|
|
|
Monocytes (high vs low)
|
1.738-9.392
|
0.001
|
|
|
Fibrinogen (high vs low)
|
2.201-11.140
|
<0.001
|
|
|
AFR (high vs low)
|
0.044-0.243
|
<0.001
|
1.350-14.469
|
0.014
|
PLR (high vs low)
|
1.180-7.135
|
0.02
|
|
|
Notes:The high vs low levels were categorized using the cut-off value based on the Youden’s Index
Abbreviations:WBC White blood cell,AFR Albumin-to-fibrinogen ratio,PLR Platelet-to-Lymphocyte ratio,OR Odds ratio,CI Confidence interval