Outcomes of acute kidney injury in critically ill adults with tropical acute febrile illness: Prospective observational study

Table 1 Baseline characteristics of the study population

Variable	Value
Age (years)	52 (37.5-60.8)
Hospital stay (days)	9 (5-12.8)
ICU stay (days)	7 (4-9.8)
Fever duration (days)	7 (5-10.5)
Temperature (°F)	100.5 (99.4-101.6)
Heart rate (minute)	105.3 ± 18.0
SBP (mmHg)	113.9 ± 18.8
DBP (mmHg)	74 (66-82)
Respiratory rate (minute)	22 (20-26)
Oxygen saturation (%)	96 (94-98)
Hemoglobin (g/dL)	10.8 ± 2.2
Platelet count (mm3)	80000 (51000-124750)
Serum creatinine (mg/dL)	1.35 (0.90-2.90)
Serum urea (mg/dL)	68.2 (43.5-127.0)
Bilirubin (mg/dL)	1.4 (0.8-3.6)
AST (U/L)	126 (67-212)
ALT (U/L)	76 (47-114)
APACHE II (admission)	15.6 ± 7.8
SOFA score (admission)	8.6 ± 3.9
Gender
Female	37 (54.4)
Male	31 (45.6)
Common symptoms
Fever	68 (100)
Nausea/vomiting	52 (76.5)
Headache/myalgia	40 (58.8)
Shortness of breath	36 (52.9)
Altered sensorium	33 (48.5)
Comorbidities
Diabetes mellitus	15 (22.1)
Hypertension	17 (25.0)
Chronic liver disease	6 (8.8)
Oxygen/ventilation
Invasive ventilation (any time during ICU stay)	27 (39.7)
NIV (any time during ICU stay)	9 (13.2)
Vasopressor use	28 (41.2)
AKI stage on admission
Stage 1	37 (54.4)
Stage 2	27 (39.71)
Stage 3	2 (2.9)
Renal replacement therapy
Dialysis required	19 (27.9)
Tropical fever etiology
Scrub typhus	43 (63.2)
Dengue (± coinfection)	18 (26.5)
Typhoid (± coinfection)	7 (10.3)
Outcomes
In-hospital mortality	8 (11.8)
Net negative outcome	23 (33.8)

Presented as mean ± SD, n (%) or median (IQR). AKI: Acute kidney injury; ALT: Alanine aminotransferase; APACHE-II: Acute Physiology and Chronic Health Evaluation II; AST: Aspartate aminotransferase; DBP: Diastolic blood pressure; ICU: Intensive care unit; IQR: Interquartile range; NIV: Non-invasive ventilation; SBP: Systolic blood pressure; SOFA: Sequential organ failure assessment.

Table 2 Univariate analysis for in-hospital mortality

Variable	Survivors (n = 60)	Non-survivors (n = 8)	P value
Age (years)	54 (39-61)	45 (26-60)	0.319
Hospital stay (days)	9 (6-13)	6 (4-9)	0.192
FiO2 on admission (%)	32 (21-53)	55 (25-67)	0.099
Hemoglobin on admission (g/dL)	10.9 ± 1.8	9.6 ± 4.1	0.115
Serum creatinine on admission (mg/dL)	1.35 (0.9-2.9)	1.28 (0.6-5.7)	0.165
APACHE-II on admission	15.1 ± 7.4	19.1 ± 10.6	0.176
SOFA score on admission	8.7 ± 3.8	8.5 ± 4.3	0.919
Bleeding	5 (7.4)	3 (37.5)	0.016
NIV use during ICU stay	6 (10.0)	3 (37.5)	0.031
Blood product transfusion	6 (10.0)	4 (50.0)	0.003
Dengue infection	13 (21.7)	5 (62.5)	0.014
AKI stage ≥ 2 on admission	25 (41.7)	4 (50.0)	0.848
Dialysis requirement	16 (26.7)	3 (37.5)	0.521
Renal non-recovery at discharge	2 (3.3)	8 (100)	< 0.001
Invasive ventilation	24 (40.0)	3 (37.5)	0.892
Vasopressor use	26 (43.3)	2 (25.0)	0.322

Presented as mean ± SD, n (%) or median (IQR). Variables with P < 0.10 were considered for multivariable analysis. AKI: Acute kidney injury; APACHE-II: Acute Physiology and Chronic Health Evaluation II; ICU: Intensive care unit; IQR: Interquartile range; NIV: Non-invasive ventilation; SOFA: Sequential organ failure assessment.

Table 3 Exploratory multivariable logistic regression analyses for in-hospital mortality

Variable	β (SE)	Odds ratio, exp (β)	95%CI for OR	P value
Age (years)	-0.117 (0.054)	0.889	0.800-0.989	0.030
Fever duration (days)	-0.269 (0.144)	0.764	0.576-1.014	0.062
FiO2 on admission	0.091 (0.042)	1.095	1.008-1.190	0.032
Serum creatinine on admission (mg/dL)	0.982 (0.750)	2.671	0.614-11.619	0.190
Worst serum creatinine (mg/dL)	-0.307 (0.839)	0.736	0.142-3.808	0.714
APACHE-II on admission	0.422 (0.217)	1.525	0.997-2.333	0.052
APACHE-II at 48 hours	-0.395 (0.261)	0.673	0.403-1.124	0.130
SOFA score on admission	-0.877 (0.470)	0.416	0.165-1.046	0.062
SOFA score at 48 hours	0.684 (0.543)	1.981	0.684-5.743	0.208
Dialysis requirement	-0.867 (1.407)	0.42	0.027-6.618	0.538

Model statistics: Omnibus χ² = 21.83, df = 10, P = 0.016; -2 Log likelihood = 27.43; Cox & Snell R² = 0.275; Nagelkerke R² = 0.533; Hosmer-Lemeshow χ² = 1.59, df = 8, P = 0.991. Disclaimer: Binary logistic regression models were used. Odds ratios (OR) < 1 indicate reduced odds of adverse outcome with increasing predictor values. Variables with P < 0.05 were considered statistically significant. Results should be interpreted cautiously given the limited number of outcome events. APACHE-II: Acute Physiology and Chronic Health Evaluation II; SOFA: Sequential organ failure assessment; OR: Odds ratio; CI: Confidence interval.

Table 4 Exploratory multivariable logistic regression analyses for net negative outcome at hospital discharge

Variable	β (SE)	Odds ratio, exp (β)	95%CI for OR	P value
Age (years)	-0.086 (0.039)	0.917	0.849-0.990	0.027
Fever duration (days)	-0.177 (0.072)	0.838	0.728-0.965	0.014
FiO2 on admission	0.076 (0.026)	1.079	1.025-1.137	0.004
Serum creatinine on admission (mg/dL)	-0.051 (0.441)	0.951	0.401-2.256	0.909
Worst serum creatinine (mg/dL)	0.182 (0.533)	1.2	0.422-3.414	0.733
APACHE-II on admission	0.343 (0.140)	1.41	1.071-1.856	0.014
APACHE-II at 48 hours	-0.222 (0.142)	0.801	0.606-1.059	0.119
SOFA score on admission	-0.540 (0.244)	0.582	0.361-0.940	0.027
SOFA score at 48 hours	0.404 (0.252)	1.497	0.914-2.454	0.109
Dialysis requirement	-3.176 (0.996)	0.042	0.006-0.294	0.001

Model statistics: Omnibus χ² = 38.57, df = 10, P < 0.001; -2 Log likelihood = 48.45; Cox & Snell R² = 0.433; Nagelkerke R² = 0.600; Hosmer-Lemeshow χ² = 5.62, df = 8, P = 0.690. Disclaimer: Binary logistic regression models were used. Odds ratios (OR) < 1 indicate reduced odds of adverse outcome with increasing predictor values. Variables with P < 0.05 were considered statistically significant. Results should be interpreted cautiously given the limited number of outcome events. APACHE-II: Acute Physiology and Chronic Health Evaluation II; SOFA: Sequential organ failure assessment; OR: Odds ratio; CI: Confidence interval.