During the study, 150 consecutive patients were admitted to the ICU with the diagnosis of septic shock. However, 27 patients were excluded due to presence of AKI at ICU admission; 12 because of a delay in septic shock diagnosis; 4 because of the presence of advanced chronic kidney disease; 3 because PAD4 concentration below assay sensitivity; and 5 had technical problems with polymorphism analysis. Thus, we evaluated 99 patients.
The mean age was 63.6 ± 14.4 years, 56% were male, and the median length of ICU stay was 9 (4 to 17) days. The mortality rate during the ICU stay was 69.9%. Median PAD4 serum concentration was 4.4 (2.5 to 6.2) ng/mL. Among these patients with septic shock, SAKI developed in 51.5% during the ICU stay; of these, 21.5% required RRT and 80% died.
The genotype frequencies for the rs11203367 polymorphism were 49.59% for CT, 35.4% for CC and 15.1% for TT; for the rs874881 polymorphism, they were 51.5% for CG, 16.2% for GG and 32.3% for CC. These frequencies are consistent with those expected under the Hardy-Weinberg equilibrium.
The demographic and laboratory data are presented in Tables 1 and 2, respectively.
Table 1. Demographic and PADI4 polymorphisms data of 99 patients with septic shock
Variables
|
SAKI development
|
P
|
|
Yes (n = 51)
|
No (n = 48)
|
|
Age (years)
|
67 (59 -75)
|
64 (51-71)
|
0.093
|
Male, n (%)
|
27 (53)
|
28 (58)
|
0.736
|
APACHE II score
|
18.8 + 6.0
|
16.5 + 6.8
|
0.070
|
SOFA score
|
10.4 + 2.7
|
8.8 + 2.3
|
0.002
|
Sepsis focus, n (%)
|
|
|
0.203
|
Respiratory
|
35 (69)
|
23 (48)
|
|
Abdominal
|
11 (22)
|
12 (25)
|
|
Urinary
|
1 (2)
|
3 (6)
|
|
Outros
|
4 (7)
|
10 (21)
|
|
Mortality ICU, n (%)
|
41 (80)
|
28 (58)
|
0.003
|
PADI4 (rs11203367), n (%)
|
|
|
0.910
|
CT
|
26 (51)
|
23 (48)
|
|
CC
|
17 (33)
|
18 (37.5)
|
|
TT
|
8 (16)
|
7 (14.5)
|
|
PADI4 (rs874881), n (%)
|
|
|
0.769
|
CG
|
28 (55)
|
23 (48)
|
|
GG
|
8 (16)
|
8 (17)
|
|
CC
|
15 (29)
|
17 (35)
|
|
APACHE II = Acute Physiology and Chronic Health Evaluation, ICU = intensive care unit, PADI4 = polymorphisms peptidylarginine deiminase 4, SOFA = Sequential Organ Failure Assessment. Data are expressed as the mean ± SD. median (including the lower and upper quartiles) or percentage.
Table 2. Laboratory data of 99 patients with septic shock
Variable
|
SAKI development
|
P
|
|
Yes (n = 51)
|
No (n = 48)
|
|
PAD4 (ng/mL)
|
4.6 (3.1- 6.7)
|
3.8 (1.9 - 6.2)
|
0.116
|
Lactate (mmol/L)
|
2.3 (1.4 – 3.5)
|
2.3 (1.2 – 3.8)
|
0.890
|
Hemoglobin (g/dL)
|
10.7 + 2.0
|
11.4 + 2.1
|
0.072
|
Hematocrit (%)
|
32.2 + 6.1
|
34.0 + 6.1
|
0.155
|
Leucocytes (103/mm3)
|
17.0 (13.2 – 22.4)
|
16.5 (11.0 – 24.6)
|
0.872
|
CRP (mg/dL)
|
36.5 (28.0 – 44.1)
|
30.5 (8.2 – 35.5)
|
0.030
|
Albumin, (g/dL)
|
2.3 (2.0 – 2.5)
|
2.1 (1.8 – 2.6)
|
0.427
|
Urea, (mg/dL)
|
101 (68 – 160)
|
53 (33 – 85)
|
<0.001
|
Creatinine, (mg/dL)
|
2.0 (1.6 – 2.6)
|
0.8 (0.5 – 1.1)
|
<0.001
|
CRP = C-reactive protein, PAD4 = peptidylarginine deiminase 4; SAKI = sepsis-induced acute kidney injury. Data are expressed as mean ± standard deviation or median (including the lower and upper quartiles).
Patients with SAKI had higher Sequential Organ Failure Assessment (SOFA) score, higher serum concentration of C-reactive protein (CRP), urea, and creatinine, and higher mortality rate. There were no differences between PAD4 concentrations and its polymorphisms rs11203367 and rs87481 in patients in whom SAKI developed or not. Nevertheless, it is relevant to note that the serum concentration of PAD4 had a positive correlation with plasma urea (r = 0.269; p = 0.007) and creatinine concentration (r = 0.284; p = 0.004).
Patients with SAKI who died in the ICU had higher Acute Physiology and Chronic Health Evaluation (APACHE II) and SOFA scores. However, there were no differences between PAD4 concentrations and its polymorphisms rs11203367 and rs874881 in patients who died during the ICU stay (Table 3).
Table 3. Demographic, PAD 4 serum concentration and PADI4 polymorphisms data of 51 patients with SAKI
Variables
|
Mortality ICU
|
P
|
|
Yes (n = 41)
|
No (n = 10)
|
|
Age (years)
|
66.5 + 12.8
|
64.5 + 11.4
|
0.624
|
Male, n (%)
|
21 (51)
|
6 (60)
|
0.731
|
APACHE II score
|
19.7 + 6.1
|
15.4 + 4.3
|
0.043
|
SOFA score
|
10.8 + 2.7
|
8.6 + 1.7
|
0.020
|
Sepsis focus, n (%)
|
|
|
0.507
|
Respiratory
|
29 (71)
|
6 (60)
|
|
Abdominal
|
7 (17)
|
4 (40)
|
|
Urinary
|
1 (2)
|
0 (0)
|
|
Others
|
4 (10)
|
(0)
|
|
PAD 4, (ng/mL)
|
4.7 (3.1-6.8)
|
3.9 (2.4-7.2)
|
0.678
|
PADI4 (rs11203367), n (%)
|
|
|
0.780
|
CT
|
20 (49)
|
6 (60)
|
|
CC
|
14 (34)
|
3 (30)
|
|
TT
|
7 (17)
|
1 (10)
|
|
PADI4 (rs874881), n (%)
|
|
|
0.563
|
CG
|
21 (51)
|
7 (70)
|
|
GG
|
7 (17)
|
1 (10)
|
|
CC
|
13 (32)
|
2 (20)
|
|
APACHE II = Acute Physiology and Chronic Health Evaluation, PAD4 = peptidylarginine deiminase 4, PADI4 = polymorphisms peptidylarginine deiminase 4, SOFA = Sequential Organ Failure Assessment. Data are expressed as the mean ± standard deviation. median (including the lower and upper quartiles) or percentage.
Patients with SAKI who needed RRT had a higher SOFA score, but the same association was not observed with PAD4 concentration and PADI4 polymorphisms (Table 4).
Table 4. Demographic, PAD4 serum concentration and PADI4 polymorphisms data of 51 patients with SAKI
Variables
|
RRT ICU
|
P
|
|
Yes (n = 11)
|
No (n = 40)
|
|
Age (years)
|
63.2 + 14.1
|
67.1 + 12.1
|
0.365
|
Male, n (%)
|
4 (36)
|
23 (58)
|
0.367
|
APACHE II score
|
21.8 + 6.4
|
18.0 + 5.7
|
0.061
|
SOFA score
|
12.0 (12.0 - 15.0)
|
9.5 (8.0 - 11.0)
|
0.003
|
PAD4 (ng/mL)
|
4.6 (3.1 - 9.3)
|
4.5 (2.8 - 6.1)
|
0.384
|
PADI4 (rs11203367), n (%)
|
|
|
0.102
|
CT
|
4 (36.5)
|
22 (55)
|
|
CC
|
4 (36.5)
|
14 (35)
|
|
TT
|
3 (27)
|
4 (10)
|
|
PADI4 (rs874881), n (%)
|
|
|
0.094
|
CG
|
4 (36.5)
|
24 (60)
|
|
GG
|
4 (36.5)
|
4 (10)
|
|
CC
|
3 (27)
|
12 (30)
|
|
APACHE II = Acute Physiology and Chronic Health Evaluation; ICU = intensive care unit, SOFA = Sequential Organ Failure Assessment, PAD 4 = peptidylarginine deiminase 4; PADI4: polymorphisms peptidylarginine deiminase 4, RRT, renal replacement therapy. Data are expressed as the mean ± standard deviation, median (including the lower and upper quartiles) or percentage.