3.1 Subject Characteristics According to the admission criteria, three hundred and twenty-one adult patients met the criteria of this study. The screening flow chart is shown in Figure 1.
Baseline data of the patients are shown in Table 1. Based on the values of serum phosphate on admission, all enrolled patients were divided into four groups equally: <2.6mg/dl, 78 patients(24.2%); 2.6-3.4mg/dl, 81 patients(25.2%); 3.5-4.5mg/dl, 79 patients(24.5%) and >4.5mg/dl, 83 patients(25.8%), respectively. Of the 321 patients, the mean age was 53.8±16.9 years. 217(67.6%) patients were male and 104 (32.4%) were female. 221(68.8%) patients were white people and black people 42 (13.1%) were black people. Hispanic and asian people maked up only a small percentage. Further comparison were made among the four different groups. The result showed that patients with higher phosphate levels had older age, higher values of mean SPO2, CK, CR, BUN, AST, potassium, lactate and had lower mean temperature and lower calcium, the p-value was less than 0.05. Moreover, patients with higher phosphate levels tended to have higher SOFA score and APSⅢ score, as well as higher probability of receiving RRT treatment than other patients.
3.2 Incidence of AKI AKI occurred in 204 patients(63.6%) with rhabdomyolysis. The incidence of AKI was 52.6%, 56.8%, 68.4% and 75.9% with phosphate groups <2.6, 2.6-3.4, 3.5-4.5 and>4.5mg/dl, respectively. Patients with phosphate>4.5mg/dl were found to have the highest AKI incidence, with the association preserved for all stages of AKI (Table 1). The characteristics and their comparison with or without AKI are displayed in Table 2. The AKI group had higher phosphate, potassium, CR values, SOFA score and APSⅢ score. They also tended to have AF, to use RRT than non-AKI group and to stay longer in hospital. No differences were observed in most variables between the AKI group and non-AKI gourp(age, gender, ethnicity, MAP, HR, RR, temperature, SPO2, CK, BUN, ALT, AST, platelet, bicarbonate, HCT, HGB, calcium, sodium, potassium, lactate, WBC, RDW, hypertension, diabetes, AHF, ALF, ARDS, stroke, p-value>0.05).
3.3 Characteristics between AKI stage groups We further compared the characteristics of the patients among three stages of AKI (Table 3). Of the 204 patients who developed AKI, 46 patients were in stage 1, 76 patients were in stage 2 and 82 patients were in stage 3. The trend of each stage with the elevated phosphate levels was shown in a line chart in Figure 2. Incidence of AKI showed no single upward or downward trend in stage 1 and stage 2. In stage 1, it presented a gradual decline. Stage 2 showed a trend of rising and then falling, the highest incidence occurred in the second group with phosphate 2.6-3.4mg/dl. Stage 3 showed an obvious upward trend with the increase of phosphate levels. Patients of phosphate more than 4.5mg/dl in stage 3 had the highest incidence of AKI(12.1%). Patients from stage 3 also had higher CK, CR, BUN, bicarbonate, potassium values, SOFA score and APSⅢ score and lower calcium values than the other two stages. ALF, AF and use of RRT were more easily to discover in the stage 3 group.
Table 1
Characteristics of the study population based on four phosphate groups
Characteristics
|
All
|
phosphate levels (mg/dL)
|
P
|
<2.6
|
2.6-3.4
|
3.5-4.5
|
>4.5
|
N
|
321
|
78
|
81
|
79
|
83
|
|
Age(year)
|
53.8 ± 16.9
|
49.1 ± 16.6
|
55.2 ± 18.3
|
53.8 ± 17.2
|
56.8 ± 14.6
|
0.026
|
Gender(n,%)
|
|
|
|
|
|
0.97
|
male
|
217 (67.6%)
|
51 (65.4%)
|
55 (67.9%)
|
54 (68.4%)
|
57 (68.7%)
|
|
female
|
104 (32.4%)
|
27 (34.6%)
|
26 (32.1%)
|
25 (31.6%)
|
26 (31.3%)
|
|
Ethnicity(n,%)
|
|
|
|
|
|
0.623
|
asian
|
4 (1.2%)
|
1 (1.3%)
|
3 (3.7%)
|
0 (0.0%)
|
0 (0.0%)
|
|
hispanic
|
11 (3.4%)
|
1 (1.3%)
|
4 (4.9%)
|
4 (5.1%)
|
2 (2.4%)
|
|
black
|
42 (13.1%)
|
10 (12.8%)
|
9 (11.1%)
|
13 (16.5%)
|
10 (12.0%)
|
|
white
|
221 (68.8%)
|
55 (70.5%)
|
54 (66.7%)
|
53 (67.1%)
|
59 (71.1%)
|
|
other
|
43 (13.4%)
|
11 (14.1%)
|
11 (13.6%)
|
9 (11.4%)
|
12 (14.5%)
|
|
AKI(n,%)
|
204 (63.6%)
|
41 (52.6%)
|
46 (56.8%)
|
54 (68.4%)
|
63 (75.9%)
|
0.008
|
MAP(mmHg)
|
82.0 ± 12.1
|
84.3 ± 13.1
|
81.9 ± 13.0
|
81.4 ± 9.5
|
80.4 ± 12.5
|
0.223
|
HR(/min)
|
92.7 ± 15.4
|
94.6 ± 16.0
|
92.5 ± 16.4
|
91.8 ± 13.6
|
92.2 ± 15.5
|
0.674
|
RR(/min)
|
19.7 ± 3.8
|
19.7 ± 3.8
|
19.4 ± 3.7
|
19.8 ± 3.4
|
20.0 ± 4.4
|
0.756
|
Temperature(℃)
|
37.0 ± 0.7
|
37.3 ± 0.8
|
37.1 ± 0.6
|
37.0 ± 0.7
|
36.8 ± 0.6
|
0.002
|
SP02(%)
|
96.9 ± 3.4
|
97.3 ± 1.6
|
96.9 ± 4.0
|
96.0 ± 4.8
|
97.4 ± 1.8
|
0.034
|
RRT(n,%)
|
57 (17.8%)
|
7 (9.0%)
|
8 (9.9%)
|
14 (17.7%)
|
28 (33.7%)
|
<0.001
|
LOS in hospital(day)
|
10.0 (5.9-18.2)
|
8.8 (5.6-14.9)
|
8.7 (4.8-16.4)
|
10.7 (6.3-21.0)
|
13.6 (7.9-23.1)
|
0.122
|
AKI(n,%)
|
204 (63.6%)
|
41 (52.6%)
|
46 (56.8%)
|
54 (68.4%)
|
63 (75.9%)
|
0.008
|
AKI Stage(n,%)
|
|
|
|
|
|
<0.001
|
1
|
46 (22.5%)
|
18 (43.9%)
|
8 (17.4%)
|
12 (22.2%)
|
8 (12.7%)
|
|
2
|
76 (37.3%)
|
13 (31.7%)
|
26 (56.5%)
|
21 (38.9%)
|
16 (25.4%)
|
|
3
|
82 (40.2%)
|
10 (24.4%)
|
12 (26.1%)
|
21 (38.9%)
|
39 (61.9%)
|
|
Lab parameters
|
|
|
|
|
|
|
CK(U/L)
|
5143.0 (1744.0-15621.5)
|
4543.5 (1882.2-12113.2)
|
3725.0 (1597.0-10204.0)
|
5832.0 (1743.0-15621.5)
|
9140.0 (2040.5-32745.0)
|
<0.001
|
BUN(mg/dL)
|
24.0 (15.0-42.0)
|
21.0 (12.0-30.8)
|
18.0 (13.0-28.0)
|
23.0 (17.0-33.0)
|
56.0 (29.5-77.0)
|
<0.001
|
ALT(U/L)
|
179.0 (52.0-321.7)
|
94.5 (46.2-321.7)
|
176.0 (43.0-321.7)
|
321.7 (62.0-321.7)
|
196.0 (67.0-321.7)
|
0.055
|
AST(U/L)
|
476.0 (115.0-626.0)
|
221.0 (98.8-626.0)
|
339.0 (91.0-626.0)
|
626.0 (148.0-626.0)
|
626.0 (149.0-779.5)
|
0.011
|
Platelet(1000/mm3)
|
201.4 (126.0-256.0)
|
160.5 (104.0-224.0)
|
228.0 (139.0-266.0)
|
204.0 (152.0-246.0)
|
195.0 (123.0-280.0)
|
0.012
|
CR(mg/dL)
|
2.0 ± 1.9
|
1.3 ± 0.9
|
1.3 ± 1.0
|
1.6 ± 1.1
|
3.8 ± 2.7
|
<0.001
|
Bicarbonate(mmol/L)
|
21.8 ± 5.2
|
22.5 ± 5.7
|
23.2 ± 4.8
|
22.1 ± 4.5
|
19.3 ± 4.8
|
<0.001
|
HCT(%)
|
34.7 ± 5.6
|
34.7 ± 5.3
|
35.1 ± 5.1
|
35.7 ± 5.8
|
33.5 ± 6.1
|
0.09
|
HGB(g/dL)
|
11.9 ± 1.9
|
11.9 ± 1.9
|
12.2 ± 1.7
|
12.2 ± 2.0
|
11.4 ± 2.1
|
0.043
|
Calcium(mg/dL)
|
7.7 ± 1.0
|
7.4 ± 1.0
|
7.9 ± 0.9
|
7.8 ± 0.8
|
7.6 ± 1.4
|
0.005
|
Sodium(mmol/L)
|
139.5 ± 6.7
|
140.2 ± 8.3
|
140.0 ± 6.4
|
139.7 ± 4.6
|
138.1 ± 7.0
|
0.173
|
Potassium(mmol/L)
|
4.2 ± 0.9
|
3.6 ± 0.7
|
3.9 ± 0.7
|
4.4 ± 0.7
|
4.9 ± 1.0
|
<0.001
|
Lactate (mmol/L)
|
2.5 ± 1.7
|
2.4 ± 1.4
|
2.5 ± 1.3
|
2.3 ± 1.1
|
3.0 ± 2.5
|
0.039
|
WBC(109/L)
|
11.7 ± 5.8
|
10.6 ± 5.7
|
11.2 ± 5.1
|
12.4 ± 5.6
|
12.7 ± 6.5
|
0.085
|
RDW(%)
|
14.4 ± 1.4
|
14.1 ± 1.4
|
14.3 ± 1.5
|
14.5 ± 1.3
|
14.6 ± 1.5
|
0.103
|
Comorbidities,n(%)
|
|
|
|
|
|
|
Hypertension
|
118 (36.8%)
|
21 (26.9%)
|
36 (44.4%)
|
28 (35.4%)
|
33 (39.8%)
|
0.128
|
Diabetes
|
57 (17.8%)
|
12 (15.4%)
|
14 (17.3%)
|
11 (13.9%)
|
20 (24.1%)
|
0.335
|
AHF
|
24 (7.5%)
|
2 (2.6%)
|
10 (12.3%)
|
4 (5.1%)
|
8 (9.6%)
|
0.081
|
ALF
|
38 (11.8%)
|
9 (11.5%)
|
7 (8.6%)
|
9 (11.4%)
|
13 (15.7%)
|
0.577
|
AF
|
42 (13.1%)
|
4 (5.1%)
|
17 (21.0%)
|
9 (11.4%)
|
12 (14.5%)
|
0.028
|
ARDS
|
4 (1.2%)
|
0 (0.0%)
|
1 (1.2%)
|
1 (1.3%)
|
2 (2.4%)
|
0.594
|
Stroke
|
29 (9.0%)
|
5 (6.4%)
|
13 (16.0%)
|
5 (6.3%)
|
6 (7.2%)
|
0.088
|
Scoring systems
|
|
|
|
|
|
|
SOFA
|
5.7 ± 3.8
|
5.1 ± 3.8
|
4.7 ± 3.4
|
5.4 ± 3.8
|
7.5 ± 3.6
|
<0.001
|
APSⅢ
|
52.7 ± 23.2
|
48.8 ± 23.4
|
47.5 ± 21.7
|
52.3 ± 24.4
|
61.9 ± 20.8
|
<0.001
|
AKI:acute kidney injury;CK:creatine kinase; CR:creatine; BUN:blood urea nitrogen; ALT:alanine transaminase; AST:aspartate aminotransferase; HCT:hematocrit; HGB:hemoglobin; WBC:white blood cell; RDW:red cell distribution width; AHF:acute heart failure; ALF:acute liver failure; AF:atrial fibrillation; ARDS:acute respiratory distress syndrome; MBP:mean blood pressure (MBP); HR:heart rate; RR:respiratory rate; RRT:renal replacement therapy; LOS:length of stay; SOFA:Sequential organ failure assessment; APSⅢ:acute physiology scoreⅢ. |
Table2: Comparison between non-AKI and AKI groups
|
Non-AKI
|
AKI
|
P
|
N
|
117
|
204
|
Age(year)
|
51.8 ± 17.4
|
54.9 ± 16.5
|
0.109
|
Gender(n,%)
|
|
|
0.087
|
male
|
86 (73.5%)
|
131 (64.2%)
|
|
female
|
31 (26.5%)
|
73 (35.8%)
|
|
Ethnicity(n,%)
|
|
|
0.118
|
asian
|
2 (1.7%)
|
2 (1.0%)
|
|
hispanci
|
7 (6.0%)
|
4 (2.0%)
|
|
black
|
17 (14.5%)
|
25 (12.3%)
|
|
white
|
81 (69.2%)
|
140 (68.6%)
|
|
other
|
10 (8.5%)
|
33 (16.2%)
|
|
Phosphate(mg/dL)
|
3.4 ± 1.6
|
4.1 ± 2.0
|
<0.001
|
MAP(mmHg)
|
83.6 ± 12.7
|
81.1 ± 11.8
|
0.078
|
HR(/min)
|
90.8 ± 15.5
|
93.9 ± 15.2
|
0.080
|
RR(/min)
|
19.4 ± 3.2
|
19.9 ± 4.1
|
0.216
|
Temperature(℃)
|
37.1 ± 0.6
|
37.0 ± 0.8
|
0.096
|
SP02(%)
|
97.4 ± 1.7
|
96.6 ± 4.0
|
0.061
|
RRT(n,%)
|
5 (4.3%)
|
52 (25.5%)
|
<0.001
|
LOS in hospital(day)
|
11.6 ± 15.0
|
16.5 ± 13.9
|
0.003
|
CK(U/L)
|
4925.0 (2023.0-13643.0)
|
5705.5 (1713.8-15621.5)
|
0.075
|
BUN(mg/dL)
|
22.0 (11.0-42.0)
|
25.0 (17.0-42.2)
|
0.464
|
ALT(U/L)
|
106.0 (44.0-321.7)
|
239.5 (62.5-321.7)
|
0.083
|
AST(U/L)
|
269.0 (115.0-626.0)
|
624.5 (120.0-626.0)
|
0.055
|
Platelet(1000/mm3)
|
205.0 (145.0-253.0)
|
198.0 (122.0-257.2)
|
0.374
|
CR(mg/dL)
|
1.1 (0.8-2.1)
|
1.3 (0.9-2.9)
|
0.014
|
Bicarbonate(mmol/L)
|
22.1 ± 5.1
|
21.6 ± 5.2
|
0.361
|
HCT(%)
|
34.2 ± 5.5
|
35.0 ± 5.7
|
0.242
|
HGB(g/dL)
|
11.9 ± 1.8
|
12.0 ± 2.0
|
0.703
|
Calcium(mg/dL)
|
7.8 ± 0.8
|
7.6 ± 1.2
|
0.135
|
Sodium(mmol/L)
|
140.1 ± 7.2
|
139.2 ± 6.4
|
0.261
|
Potassium(mmol/L)
|
4.0 ± 0.8
|
4.3 ± 1.0
|
0.005
|
Lactate(mmol/L)
|
2.4 ± 1.7
|
2.6 ± 1.7
|
0.261
|
WBC(109/L)
|
11.0 ± 5.7
|
12.1 ± 5.9
|
0.108
|
RDW(%)
|
14.3 ± 1.4
|
14.4 ± 1.5
|
0.711
|
Hypertension(n,%)
|
41 (35.0%)
|
77 (37.7%)
|
0.629
|
Diabetes(n,%)
|
22 (18.8%)
|
35 (17.2%)
|
0.710
|
AHF(n,%)
|
7 (6.0%)
|
17 (8.3%)
|
0.441
|
ALF(n,%)
|
10 (8.5%)
|
28 (13.7%)
|
0.167
|
AF(n,%)
|
9 (7.7%)
|
33 (16.2%)
|
0.030
|
ARDS(n,%)
|
0 (0.0%)
|
4 (2.0%)
|
0.127
|
Stroke(n,%)
|
6 (5.1%)
|
23 (11.3%)
|
0.064
|
SOFA
|
4.2 ± 2.8
|
6.5 ± 4.1
|
<0.001
|
APSⅢ
|
43.9 ± 16.7
|
57.8 ± 24.8
|
<0.001
|
AKI:acute kidney injury;CK:creatine kinase; CR:creatine; BUN:blood urea nitrogen; ALT:alanine transaminase; AST:aspartate aminotransferase; HCT:hematocrit; HGB:hemoglobin; WBC:white blood cell; RDW:red cell distribution width; AHF:acute heart failure; ALF:acute liver failure; AF:atrial fibrillation; ARDS:acute respiratory distress syndrome; MBP:mean blood pressure (MBP); HR:heart rate; RR:respiratory rate; RRT:renal replacement therapy; LOS:length of stay; SOFA:Sequential organ failure assessment; APSⅢ:acute physiology scoreⅢ.
Table 3
Comparison among patients according to AKI stage
Characteristics
|
AKI
|
P
|
Stage 1
|
Stage 2
|
Stage 3
|
N
|
46
|
76
|
82
|
|
Age(year)
|
52.6 ± 16.0
|
58.3 ± 16.1
|
53.1 ± 16.9
|
0.077
|
Gender(n,%)
|
|
|
|
0.923
|
male
|
29 (63.0%)
|
48 (63.2%)
|
54 (65.9%)
|
|
female
|
17 (37.0%)
|
28 (36.8%)
|
28 (34.1%)
|
|
Ethnicity(n,%)
|
|
|
|
0.851
|
asian
|
1 (2.2%)
|
0 (0.0%)
|
1 (1.2%)
|
|
hispanci
|
5 (10.9%)
|
12 (15.8%)
|
8 (9.8%)
|
|
black
|
1 (2.2%)
|
1 (1.3%)
|
2 (2.4%)
|
|
white
|
6 (13.0%)
|
11 (14.5%)
|
16 (19.5%)
|
|
other
|
33 (71.7%)
|
52 (68.4%)
|
55 (67.1%)
|
|
MAP(mmHg)
|
82.4 ± 11.3
|
80.1 ± 11.6
|
81.3 ± 12.2
|
0.554
|
HR(/min)
|
90.9 ± 16.0
|
93.7 ± 13.5
|
95.7 ± 16.1
|
0.23
|
RR(/min)
|
97.4 ± 1.8
|
97.0 ± 1.8
|
95.9 ± 5.8
|
0.067
|
Temperature(℃)
|
37.0 ± 0.7
|
37.1 ± 0.7
|
36.9 ± 0.8
|
0.154
|
SP02(%)
|
97.4 ± 1.8
|
97.0 ± 1.8
|
95.9 ± 5.8
|
0.067
|
RRT(n,%)
|
4 (8.7%)
|
7 (9.2%)
|
41 (50.0%)
|
<0.001
|
LOS in hospital(day)
|
11.9 ± 10.5
|
13.5 ± 9.1
|
21.8 ± 17.3
|
<0.001
|
CK(U/L)
|
4254.5 (2233.8-15621.5)
|
3499.0 (1497.8-10327.5)
|
9285.5 (1799.0-33722.2)
|
<0.001
|
BUN(mg/dL)
|
22.5 (16.0-32.2)
|
21.0 (14.0-32.0)
|
38.0 (23.0-57.8)
|
<0.001
|
ALT(U/L)
|
321.7 (56.5-321.7)
|
120.5 (41.5-321.7)
|
321.7 (84.8-321.7)
|
0.446
|
AST(U/L)
|
577.5 (102.2-626.0)
|
310.0 (98.5-626.0)
|
626.0 (187.0-895.8)
|
0.155
|
Platelet(1000/mm3)
|
202.7 (118.0-250.0)
|
207.0 (143.8-265.2)
|
184.5 (113.0-240.8)
|
0.079
|
CR(mg/dL)
|
1.1 (0.8-1.7)
|
1.0 (0.8-1.7)
|
2.9 (1.3-4.5)
|
<0.001
|
Bicarbonate(mmol/L)
|
20.8 ± 6.2
|
22.8 ± 3.7
|
20.9 ± 5.7
|
0.04
|
HCT(%)
|
35.3 ± 5.3
|
35.6 ± 5.8
|
34.4 ± 5.8
|
0.388
|
HGB(g/dL)
|
12.1 ± 1.8
|
12.1 ± 2.0
|
11.8 ± 2.1
|
0.514
|
Calcium(mg/dL)
|
7.6 ± 1.3
|
7.9 ± 1.0
|
7.4 ± 1.2
|
0.034
|
Sodium(mmol/L)
|
139.9 ± 7.4
|
139.1 ± 6.6
|
138.9 ± 5.7
|
0.669
|
Potassium(mmol/L)
|
4.0 ± 1.0
|
4.2 ± 0.8
|
4.6 ± 1.0
|
0.004
|
Lactate (mmol/L)
|
2.3 ± 1.7
|
2.6 ± 1.5
|
2.7 ± 1.7
|
0.419
|
WBC(109/L)
|
12.3 ± 6.6
|
12.4 ± 6.1
|
11.8 ± 5.2
|
0.834
|
RDW(%)
|
14.2 ± 1.6
|
14.3 ± 1.4
|
14.6 ± 1.4
|
0.218
|
Hypertension(n,%)
|
13 (28.3%)
|
36 (47.4%)
|
28 (34.1%)
|
0.074
|
Diabetes(n,%)
|
8 (17.4%)
|
16 (21.1%)
|
11 (13.4%)
|
0.445
|
AHF(n,%)
|
4 (8.7%)
|
6 (7.9%)
|
7 (8.5%)
|
0.984
|
ALF(n,%)
|
4 (8.7%)
|
6 (7.9%)
|
18 (22.0%)
|
0.02
|
AF(n,%)
|
2 (4.3%)
|
14 (18.4%)
|
17 (20.7%)
|
0.043
|
ARDS(n,%)
|
0 (0.0%)
|
2 (2.6%)
|
2 (2.4%)
|
0.55
|
Stroke(n,%)
|
5 (10.9%)
|
11 (14.5%)
|
7 (8.5%)
|
0.497
|
SOFA
|
4.9 ± 2.9
|
4.7 ± 3.3
|
9.1 ± 4.0
|
<0.001
|
APSⅢ
|
48.7 ± 25.4
|
47.3 ± 16.2
|
72.5 ± 24.0
|
<0.001
|
AKI:acute kidney injury;CK:creatine kinase; CR:creatine; BUN:blood urea nitrogen; ALT:alanine transaminase; AST:aspartate aminotransferase; HCT:hematocrit; HGB:hemoglobin; WBC:white blood cell; RDW:red cell distribution width; AHF:acute heart failure; ALF:acute liver failure; AF:atrial fibrillation; ARDS:acute respiratory distress syndrome; MBP:mean blood pressure (MBP); HR:heart rate; RR:respiratory rate; RRT:renal replacement therapy; LOS:length of stay; SOFA:Sequential organ failure assessment; APSⅢ:acute physiology scoreⅢ. |
3.4 Risk of AKI and phosphate levels. We built a GAM model and multivariate logistic regression models to ascertain whether admission phosphate values contributed to AKI development. Group of phosphate<2.6mg/dl(lowest incidence of AKI, 52.6%) was used as reference. The relationship between AKI and phosphate was linear after adjusting confounders and the smoothing spline plot showed a positive curve (Figure 3). The results of P trend test were statistically significant according to phosphate levels, so there was no threshold saturation effect on the curve. To test this trend, both unadjusted and adjusted models were created. It was demonstrated that an increasing risk of AKI was associated with phosphate levels (Table 4). In modelⅠ, the adjusted OR(95% CI) according to phosphate groups were 1.2 (0.6, 2.2), 1.9 (1.0, 3.7), and 2.8 (1.4, 5.5) respectively after adjusting for age and gender with P trend value 0.001 in comparison with reference group. In modelⅡ, after adjusting for age, gender, ethnicity, CK, CR, BUN, calcium, potassium, HCT, bicarbonate, RDW, hypertension, AF, stroke, SOFA score and APSⅢ score, a similar trend was observed: the adjusted OR(95% CI) were 1.1 (0.5, 2.4), 2.1 (0.9, 4.5), 2.7 (1.0, 7.4) respectively with P trend value 0.034.
Table 4
Association between risk of AKI and phosphate levels in different Logistic regression models
|
Non-adjusted
|
Adjusted I
|
Adjusted II
|
AKI
|
OR(95% CI)
|
P
|
OR(95% CI)
|
P
|
OR(95% CI)
|
P
|
Phosphate(mg/dL)
|
1.3 (1.1, 1.4)
|
0.001
|
1.3 (1.1, 1.4)
|
0.001
|
1.3 (1.1, 1.6)
|
0.012
|
Phosphate tertiles
|
|
|
|
|
|
|
<2.6
|
1.0
|
|
1.0
|
|
1.0
|
|
2.6-3.4
|
1.2 (0.6, 2.2)
|
0.593
|
1.2 (0.6, 2.2)
|
0.654
|
1.1 (0.5, 2.4)
|
0.733
|
3.5-4.5
|
1.9 (1.0, 3.7)
|
0.044
|
1.9 (1.0, 3.7)
|
0.049
|
2.1 (0.9, 4.5)
|
0.074
|
>4.5
|
2.8 (1.5, 5.6)
|
0.002
|
2.8 (1.4, 5.5)
|
0.003
|
2.7 (1.0, 7.4)
|
0.050
|
P trend
|
0.003
|
0.001
|
0.034
|
ModelⅠadjusted for age and gender. |
ModelⅡ adjusted for age, gender, ethnicity, CK, CR, BUN, ALT, AST, bicarbonate, HCT, calcium, potassium, RDW, hypertension, AF, stroke, SOFA, APSⅢ. |
OR:odds ratio; CI:confidence interval; AKI:acute kidney injury. |
3.5 Subgroup Analyses. To further determine consistency of the relationship, subgroup analyses were performed according to dichotomous variables in patients with rhabdomyolysis. 30 variables were chosen as stratas and were divided into two equal groups (Table 5). CK was the only indicator where a statistically significant interaction was observed(P=0.0196). Patients with CK of more than 4952U/L had a significantly higher risk of AKI(OR 1.5, 95% CI 1.2-1.8), whereas the other strata showed a relatively lower risk of AKI.
Table 5
Subgroup analysis of the association between phosphate and risk of AKI
Characteristic
|
N
|
OR (95% CI)
|
P
|
P for interaction
|
Age(year)
|
|
|
|
0.1491
|
<54.4
|
160
|
1.4 (1.1, 1.7)
|
0.002
|
|
≥54.4
|
161
|
1.1 (0.9, 1.4)
|
0.218
|
|
Gender(n,%)
|
|
|
|
0.5891
|
male
|
217
|
1.2 (1.1, 1.5)
|
0.01
|
|
female
|
104
|
1.4 (1.0, 1.8)
|
0.03
|
|
MAP(mmHg)
|
|
|
|
0.7190
|
<81.7
|
150
|
1.2 (1.0, 1.5)
|
0.037
|
|
≥81.7
|
171
|
1.3 (1.1, 1.6)
|
0.011
|
|
HR(/min)
|
|
|
|
0.7002
|
<92.4
|
154
|
1.2 (1.0, 1.5)
|
0.032
|
|
≥92.4
|
167
|
1.4 (1.1, 1.7)
|
0.007
|
|
RR(/min)
|
|
|
|
0.6204
|
<19.7
|
152
|
1.2 (1.0, 1.5)
|
0.055
|
|
≥19.7
|
169
|
1.3 (1.1, 1.6)
|
0.009
|
|
Temperature(℃)
|
|
|
|
0.064
|
<37.0
|
152
|
1.1 (0.9, 1.4)
|
0.177
|
|
≥37.0
|
169
|
1.5 (1.2, 1.9)
|
<0.001
|
|
SPO2(%)
|
|
|
|
0.3585
|
<97.1
|
160
|
1.3 (1.1, 1.7)
|
0.012
|
|
≥97.1
|
161
|
1.2 (1.0, 1.4)
|
0.025
|
|
CK(U/L)
|
|
|
|
0.0196
|
<4952
|
160
|
1.1 (0.9, 1.3)
|
0.613
|
|
≥4952
|
161
|
1.5 (1.2, 1.8)
|
<0.001
|
|
CR(mg/dL)
|
|
|
|
0.1440
|
<1.3
|
157
|
1.6 (1.1, 2.2)
|
0.007
|
|
≥1.3
|
164
|
1.2 (1.0, 1.4)
|
0.026
|
|
BUN(mg/dL)
|
|
|
|
0.3675
|
<24
|
155
|
1.4 (1.1, 1.9)
|
0.021
|
|
≥24
|
166
|
1.2 (1.0, 1.4)
|
0.016
|
|
ALT(U/L)
|
|
|
|
0.5729
|
<179
|
160
|
1.3 (1.1, 1.6)
|
0.009
|
|
≥179
|
161
|
1.2 (1.0, 1.5)
|
0.063
|
|
AST(U/L)
|
|
|
|
0.5714
|
<476
|
160
|
1.3 (1.1, 1.6)
|
0.013
|
|
≥476
|
161
|
1.2 (1.0, 1.4)
|
0.065
|
|
Bicarbonate(mmol/L)
|
|
|
|
0.2816
|
<22
|
151
|
1.2 (1.0, 1.4)
|
0.03
|
|
≥22
|
170
|
1.4 (1.1, 1.8)
|
0.007
|
|
HCT(%)
|
|
|
|
0.8492
|
<34.6
|
160
|
1.3 (1.1, 1.5)
|
0.012
|
|
≥34.6
|
161
|
1.3 (1.0, 1.6)
|
0.026
|
|
HGB(g/dL)
|
|
|
|
0.1872
|
<11.9
|
152
|
1.2 (1.0, 1.4)
|
0.033
|
|
≥11.9
|
169
|
1.5 (1.1, 1.9)
|
0.003
|
|
Calcium(mg/dL)
|
|
|
|
0.0899
|
<7.7
|
154
|
1.2 (1.0, 1.4)
|
0.059
|
|
≥7.7
|
167
|
1.5 (1.2, 2.0)
|
0.002
|
|
Sodium(mmol/L)
|
|
|
|
0.2152
|
<140
|
152
|
1.3 (1.1, 1.6)
|
0.013
|
|
≥140
|
169
|
1.2 (1.0, 1.4)
|
0.094
|
|
Potassium(mmol/L)
|
|
|
|
0.9634
|
<4
|
144
|
1.2 (1.0, 1.6)
|
0.112
|
|
≥4
|
177
|
1.2 (1.0, 1.5)
|
0.034
|
|
Lactate(mmol/L)
|
|
|
|
0.1242
|
<2.5
|
138
|
1.1 (0.9, 1.4)
|
0.235
|
|
≥2.5
|
183
|
1.4 (1.1, 1.7)
|
0.001
|
|
WBC(109/L)
|
|
|
|
0.7838
|
<11
|
159
|
1.3 (1.1, 1.5)
|
0.009
|
|
≥11
|
162
|
1.2 (1.0, 1.5)
|
0.056
|
|
Platelet(1000/mm3)
|
|
|
|
0.7075
|
<201
|
160
|
1.3 (1.1, 1.6)
|
0.008
|
|
≥201
|
161
|
1.2 (1.0, 1.5)
|
0.048
|
|
RDW(%)
|
|
|
|
0.0032
|
<14.1
|
158
|
1.2 (1.0, 1.5)
|
0.067
|
|
≥14.1
|
163
|
1.3 (1.1, 1.6)
|
0.005
|
|
Hypertension(n,%)
|
|
|
|
0.7464
|
No
|
203
|
1.3 (1.1, 1.5)
|
0.005
|
|
Yes
|
118
|
1.2 (1.0, 1.5)
|
0.089
|
|
Diabetes(n,%)
|
|
|
|
0.0496
|
No
|
264
|
1.3 (1.1, 1.5)
|
0.001
|
|
Yes
|
57
|
1.1 (0.8, 1.5)
|
0.388
|
|
AHF(n,%)
|
|
|
|
0.3117
|
No
|
297
|
1.3 (1.1, 1.5)
|
<0.001
|
|
Yes
|
24
|
1.0 (0.6, 1.6)
|
0.938
|
|
ALF(n,%)
|
|
|
|
0.5426
|
No
|
283
|
1.3 (1.1, 1.5)
|
0.001
|
|
Yes
|
38
|
1.1 (0.8, 1.5)
|
0.646
|
|
AF(n,%)
|
|
|
|
0.9371
|
No
|
279
|
1.3 (1.1, 1.4)
|
0.002
|
|
Yes
|
42
|
1.3 (0.7, 2.3)
|
0.392
|
|
Stroke(n,%)
|
|
|
|
0.3265
|
No
|
292
|
1.2 (1.1, 1.4)
|
0.002
|
|
Yes
|
29
|
1.9 (0.7, 4.8)
|
0.179
|
|
SOFA
|
|
|
|
0.4470
|
<5
|
140
|
1.3 (1.0, 1.7)
|
0.052
|
|
≥5
|
181
|
1.2 (1.0, 1.4)
|
0.084
|
|
APS
|
|
|
|
0.3169
|
<51
|
158
|
1.1 (0.9, 1.4)
|
0.472
|
|
≥51
|
163
|
1.3 (1.0, 1.5)
|
0.022
|
|
AKI:acute kidney injury;CK:creatine kinase; CR:creatine; BUN:blood urea nitrogen; ALT:alanine transaminase; AST:aspartate aminotransferase; HCT:hematocrit; HGB:hemoglobin; WBC:white blood cell; RDW:red cell distribution width; AHF:acute heart failure; ALF:acute liver failure; AF:atrial fibrillation; ARDS:acute respiratory distress syndrome; MBP:mean blood pressure (MBP); HR:heart rate; RR:respiratory rate; RRT:renal replacement therapy; SOFA:Sequential organ failure assessment; APSⅢ:acute physiology scoreⅢ. |