Table 2 Descriptive statistics for the GUH and UMCG dataset

Demographics

Sex (male)

183 (64.9%)

13 (87.0%)

0.718

Age, median (IQR) (year)

64 (53–74)

60 (54–66)

0.133

Height, median (IQR) (cm)

170 (165–178)

175 (172–178)

0.101

Weight, median (IQR) (kg)

75.0 (64.2–85.0)

77.0 (70.0–90.0)

0.138

APACHE II score upon admission median (IQR)

23.0 (3.0–29.0)

NA

NA

APACHE IV score upon admission median (IQR)

NA

74.0 (65–87)

NA

SOFA score on the day of sampling median (IQR)

5 (3–8)

12 (9–14)

< 0.001

ICU mortality (%)

33 (11.7%)

4 (26.7%)

0.329

Admission category (%)

Medical

118 (41.8%)

4 (26.7%)

0.599

Surgical

135 (47.9%)

8 (53.3%)

0.883

Trauma

29 (10.3%)

2 (13.3%)

0.662

TZP treatment

Duration of TZP therapy, median (IQR) (days)

3 (1–5)

3 (2–6)

0.373

Piperacillin concentration, median (IQR) (mg/L)

81.0 (54.4–121.4)

50.3 (36.5–80.9)

0.260

No. of blood samples per patient, median (IQR)

2 (1–3)

4 (1–5)

0.350

Timing of blood sample relative to the start of treatment, median (IQR) (hours)

63 (35–115)

30 (12–48)

<0.001

Time to the previous concentration median (IQR) (hours)

24 (24–48)

24 (24–24)

0.023

Lab results

Serum creatinine, median (IQR) (mg/dL)

0.69 (0.51–1.04)

0.76 (0.52–1.33)

0.255

Measured creatinine clearance, median (IQR) (mL/min)

107.5 (65.5–143.7)

96.9 (40.5–127.9)

0.125

Albumin, median (IQR) (g/L)

23.0 (20.0–26.0)

22.5 (19.0–26.0)

0.257

Platelets, median (IQR) (\(10^9\)/L)

281.0 (174.0–414.0)

160.0 (123.5–199.2)

0.729

Lactate, median (IQR) (mg/dL)

10.9 (8.5–14.3)

12.0 (9.0–18.0)

0.561

White blood cells, median (IQR) (\(10^9\)/L)

12.6 (9.9–16.9)

11.7 (8.5–19.5)

0.689

Bilirubin, median (IQR) (mg/dL)

0.60 (0.40–1.10)

0.99 (0.36–2.70)

0.468

Fluid balance in the previous 24 h median (IQR) (ml/24 h)

421.9 (− 359.7 to 1399.3)

816.5 (− 210.0 to 2328.2)

< 0.001