Introduction
Materials and methods
Cohort 1
Cohort 2
Study criteria (both cohorts 1 and 2)
Study procedures (cohort 1)
Study procedures (cohort 2)
Outcomes
Statistics
Results and discussion
Variable | Combined | Non-progressors | AKIN III |
P
|
---|---|---|---|---|
n = 77 | n = 52 | n = 25 | ||
Age, years
| 65.3 (1.6) | 63.8 (2.2) | 68.2 (1.9) | 0.13 |
Gender, % male
| 42.8% | 36.5% | 56.0% | 0.14 |
Race, n (%)
| ||||
African American | 44 (57.1%) | 29 (55.6%) | 15 (60.0%) | 0.63 |
Caucasian | 23 (29.9%) | 15 (28.8%) | 8 (32.0%) | 0.92 |
Hispanic | 10 (13.0%) | 8 (15.4%) | 2 (8.0%) | 0.48 |
Comorbidities, n (%)
| ||||
CKD | 24 (31.0%) | 17 (32.7%) | 7 (28.0%) | 0.80 |
Hypertension | 60 (78.0%) | 41 (78.8%) | 19 (76.0%) | 0.78 |
CHF | 25 (33.0%) | 15 (29.0%) | 10 (40.0%) | 0.44 |
DM | 35 (44.0%) | 22 (41.5%) | 13 (52.0%) | 0.47 |
Nephrotoxic exposure, n (%)
| ||||
NSAIDS | 8 (10.0)% | 6 (2.0%) | 2 (1.0%) | 1.00 |
Aminoglycosides | 1 (1.0%) | 0 (0.0%) | 1 (0.4%) | 0.63 |
Amphotericin | 2 (3.0%) | 2 (4.0%) | 0 (0.0%) | 1.00 |
Contrast | 21 (27.0%) | 15 (28.8%) | 6 (23.1%) | 0.79 |
Post-cardiac surgery | 9 (11.7%) | 6 (11.5%) | 3 (12.0%) | 1.00 |
Sepsis | 15 (19.5%) | 12 (23.1%) | 3 (12.0%) | 0.36 |
Clinical Data
| ||||
Baseline eGFR, ml/minute/1.73m2 | 68.6 (4.1) | 60.0 (8.8) | 73.3 (4.2) | 0.15 |
Baseline UFR (ml/hr) | 74.6 (11.6) | 95.7 (16.3) | 29.7 (4.2) | 0.001 |
Furosemide-naïve, n (%) | 29 (37.7%) | 23 (44.2%) | 6 (24.0%) | 0.13 |
Urine cast score) | 2.3 (0.13) | 2.1 (0.16) | 2.7 (0.23) | 0.05 |
FeNa above 1%, n (%)a | 14 (18.0%) | 10 (19.2%) | 4 (16.0%) | 1.00 |
CV SOFA score | 1.16 (0.3) | 1.05 (0.2) | 1.5 (0.4) | 0.37 |
APACHE II score | 17.8 (1.11) | 16.5 (1.2) | 21.6 (2.5) | 0.08 |
AKIN stage at enrollment, n (%)
| ||||
AKIN I | 41 (53.2%) | 34 (65.4%) | 7 (28.0%) | 0.003 |
AKIN II | 36 (46.7%) | 18 (34.6%) | 18 (72.0%) | 0.003 |
Outcomes, n (%)
| ||||
Death | 16 (20.7%) | 7 (13.4%) | 9 (36.0%) | 0.04 |
AKIN stage III
| 25 (32.4%) | N/A | 25 (100%) | N/A |
RRT
| 11 (14.2%) | N/A | 11 (44.0%) | N/A |
Death/AKIN III
| 32 (41.5%) | 7 (13.4%) | 25 (100.0%) | 0.001 |
Furosemide stress test characteristics
Measurement time point | Combined | Non-progressors | Progressed to AKIN III |
p
|
---|---|---|---|---|
n = 77 | n = 52 | n = 25 | ||
Hour 1
| 251 (35.2) | 329 (46.0) | 89 (33.0) | 0.001 |
Hour 2
| 296 (35.8) | 392 (42.2) | 96 (46.6) | 0.001 |
Hour 3
| 246 (26.6) | 311 (31.7) | 109 (35.4) | 0.001 |
Hour 4
| 207 (24.1) | 265 (31.1) | 88 (23.4) | 0.001 |
Hour 5
| 175 (18.6) | 219 (22.8) | 83 (23.7) | 0.001 |
Hour 6
| 155 (17.4) | 194 (22.3) | 75 (17.4) | 0.001 |
A | |||
---|---|---|---|
Urine output measurement time point | ROC AUCs | ||
Cohort 1 | Cohort 2 | Combined | |
n = 23 | n = 54 | n = 77 | |
One hour
| 0.83 (0.11) | 0.82 (0.07) | 0.82 (0.05) |
Two hours
| 0.87 (0.09) | 0.87 (0.07) | 0.87 (0.05) |
Three hours
| 0.84 (0.09) | 0.87 (0.07) | 0.86 (0.05) |
Four hours
| 0.85 (0.09) | 0.87 (0.07) | 0.86 (0.05) |
Five hours
| 0.85 (0.09) | 0.87 (0.07) | 0.85 (0.05) |
Six hours
| 0.85 (0.09) | 0.86 (0.07) | 0.85 (0.05) |
B
Furosemide stress test receiver operation characteristics for progression to AKIN stage III or death
| |||
Urine output measurement time point
|
ROC AUCs
| ||
Cohort 1
|
Cohort 2
|
Combined
| |
n
= 23
|
n
= 54
|
n
= 77
| |
One hour
| 0.86 (0.11) | 0.74 (0.08) | 0.79 (0.06) |
Two hours
| 0.89 (0.09) | 0.76 (0.08) | 0.81 (0.06) |
Three hours
| 0.87 (0.09) | 0.76 (0.08) | 0.80 (0.06) |
Four hours
| 0.87 (0.09) | 0.76 (0.08) | 0.80 (0.06) |
Five hours
| 0.88 (0.09) | 0.77 (0.08) | 0.81 (0.06) |
Six hours
| 0.87 (0.09) | 0.76 (0.08) | 0.80 (0.06) |
A | ||
---|---|---|
Combined cohort | ||
Total urine output over 2 hours | Sensitivity | Specificity |
≤100 ml
| 90.2% | 60.0% |
<200 ml
| 87.1% | 84.1% |
<300 ml
| 85.3% | 88.0% |
<400 ml
| 66.7% | 88.0% |
<500 ml
| 50.5% | 88.0% |
B
Sensitivity and specificity of two hour urine thresholds for progression to AKIN III or death
| ||
Combined cohort
| ||
Total urine output over two hours
|
Sensitivity
|
Specificity
|
<100 ml
| 93.3% | 53.2% |
<200 ml
| 90% | 74.2% |
<300 ml
| 87.8% | 77.4% |
<400 ml
| 66.7% | 77.4% |
<500 ml
| 53.3% | 77.4% |
Conclusions
Key Messages
-
The furosemide stress test (FST) is feasible and well-tolerated in critically ill patients with early AKI.
-
The performance of the FST to predict the primary outcome was robust and consistent in both cohorts, with a range in ROC AUC of 0.82 to 0.87.
-
Patients should be euvolemic before undertaking any type of furosemide challenge, and volume replacement is mandatory in patients who are not obviously volume overloaded.
-
FST should be conducted in an appropriate clinical setting where UO, heart rate, and blood pressure can be monitored frequently.
-
FST is a novel dynamic functional assessment of tubular function that appears to have good predictive capacity to identify those patients who will progress to advanced-stage AKI. Further validation studies of the FST are warranted.