Impact of interleukin 6 levels on acute lung injury risk and disease severity in critically ill sepsis patients

Table 1 Baseline characteristics of the study participants

Characteristic	All Patients	ALI	No ALI	MODS	No MODS
Age in yr	62.4 ± 16.8	65.2 ± 15.1	60.1 ± 17.9	67.3 ± 14.2	59.8 ± 17.5
Male sex	49 (59.0)	23 (60.5)	26 (57.8)	18 (62.1)	31 (57.4)
BMI (kg/m2)	26.8 ± 4.9	27.2 ± 5.3	26.5 ± 4.6	27.6 ± 5.1	26.4 ± 4.8
Comorbidities
Diabetes mellitus	22 (26.5)	12 (31.6)	10 (22.2)	10 (34.5)	12 (22.2)
Hypertension	35 (42.2)	19 (50.0)	16 (35.6)	16 (55.2)	19 (35.2)
Cardiovascular disease	16 (19.3)	9 (23.7)	7 (15.6%)	7 (24.1%)	9 (16.7%)
Source of infection
Pneumonia	32 (38.6)	21 (55.3)	11 (24.4)	14 (48.3)	18 (33.3)
Intra-abdominal	20 (24.1)	7 (18.4)	13 (28.9)	6 (20.7)	14 (25.9)
Urinary tract	15 (18.1)	5 (13.2)	10 (22.2)	4 (13.8)	11 (20.4)
Skin/soft tissue	8 (9.6)	2 (5.3)	6 (13.3)	2 (6.9%)	6 (11.1)
APACHE II score, median (IQR)	22 (17-27)	26 (21-31)	18 (14-23)	28 (24-33)	19 (15-24)
SOFA score, median (IQR)	8 (5-11)	11 (8-14)	6 (4-8)	13 (10-16)	6 (4-8)

Data are n (%) or mean ± standard deviation. ALI: Acute lung injury; APACHE II: Acute Physiology and Chronic Health Evaluation II; BMI: Body mass index; IQR: Interquartile range; MODS: Multiple organ dysfunction syndrome; SOFA: Sequential Organ Failure Assessment.

Table 2 Distribution of plasma interleukin 6 levels in patients with and without acute lung injury and multiple organ dysfunction syndrome

Groups	Median IL-6 in pg/mL	Interquartile range
ALI	125.6	88.4-172.9
No ALI	48.3	32.1-72.6
MODS	142.9	102.4-196.7
No MODS	58.7	37.8-85.2

Data are mean ± standard deviation. ALI: Acute lung injury; IL: Interleukin; MODS: Multiple organ dysfunction syndrome.

Table 3 Correlation between plasma interleukin 6 levels and Acute Physiology and Chronic Health Evaluation II scores

APACHE II score	Median IL-6 in pg/mL	Interquartile range
10-14	32.8	25.6-41.2
15-19	62.1	48.7-79.3
20-24	98.5	75.4-122.7
25-29	146.2	115.8-176.4
≥ 30	198.6	162.7-235.8

Data are mean ± standard deviation. Spearman's r = 0.72 (P < 0.001). APACHE II: Acute Physiology and Chronic Health Evaluation II; IL: Interleukin.

Table 4 Correlation between plasma interleukin 6 levels and Sequential Organ Failure Assessment scores

SOFA score	Median IL-6 in pg/mL	Interquartile range
2-4	39.7	28.9-51.6
5-7	72.5	53.2-94.7
8-10	121.8	95.6-149.5
11-13	167.3	137.8-203.2
≥ 14	221.6	185.9-264.7

Data are mean ± standard deviation. Spearman's r = 0.68 (P < 0.001). IL-6: Interleukin 6; SOFA: Sequential Organ Failure Assessment.

Table 5 Receiver operating characteristic curve analysis for the prediction of acute lung injury and multiple organ dysfunction syndrome using plasma interleukin 6 levels

Outcome	Cut-off in pg/mL	Sensitivity	Specificity	PPV	NPV	AUC (95%CI)
ALI	92.5	76.3	80.0	72.7	82.9	0.84 (0.75-0.93)
MODS	118.7	72.4	85.2	75.0	83.8	0.82 (0.72-0.91)

ALI: Acute lung injury; AUC: Area under the curve; CI: Confidence interval; MODS: Multiple organ dysfunction syndrome; NPV: Negative predictive value; PPV: Positive predictive value.