Plasma calprotectin in the emergency department: a potential clinical biomarker for patients with infectious diseases

Figures & data

Table 1. Baseline characteristics for patients.

Variable	Patients (Median (IQR) unless otherwise specified)
Number of participants	1287
Female	54%
Age at survey (years)	74 (63–84)
Body mass index (kg/m^2)	26 (23–30)
Admitted to hospital care	60%
Vital parameters
Systolic blood pressure (mmHg)	141 (126–164)
Diastolic blood pressure (mmHg)	80 (70–91)
Heart rate (frequency)	89 (77–104)
Respiratory rate (frequency)	24 (20–28)
Blood oxygen saturation (%)	95 (90–97)
Body temperature (degree Celsius)	36.9 (36.5–37.3)
METTS-A (%)
Red	14%
Orange	33%
Yellow	48%
Green	5%
Laboratory parameters
Calprotectin (mg/L)	0.5 (0.25–1.0)
C-reactive protein (mg/L)	11 (3.4–36)
White blood cell count (10^9/L)	9 (7.1–11.6)
Lactate (mmol/L)	1.5 (1.2–2.1)
Creatinine (µmol/L)	81 (65–107)
Comorbidities (%)
Diabetes	19%
Cancer	20%
Hypertension	42%
Chronic heart failure	35%
Coronary artery disease	31%
COPD	31%
Asthma	10%
Current smoker	18%
Previous smoker	51%

Median values (with IQR). Calprotectin, CRP, lactate and creatinine were analyzed in plasma.

Table 2. Association between calprotectin and baseline characteristics.

Variable	Calprotectin (B (95% CI))
Sex	0.038 (−0.72;0.15)
Age at survey (years)	0.002 (−0.001;0.005)
Body mass index (kg/m^2)	−0.008 (−0.02;0.001)
Systolic blood pressure (mmHg)	−0.001 (−0.003;0.000)
Diastolic blood pressure (mmHg)	−0.003 (−0.006;0.001)
Respiratory rate (frequency)	0.015 (0.008;0.022)***
C-reactive protein (CRP, mg/L)	0.26 (0.23;0.29)***
Body temperature (centigrade)	0.19 (0.11;0.28)***
White blood cell count (10^9/L)	0.18 (0.01;0.02)***
Lactate (mmol/L)	0.06 (0.005;0.11)*
Creatinine (µmol/L)	0.001 (0.00;0.002)*

* p < .05, ***p < .001.

Logarithmic calprotectin and CRP were used only for regression analyses. Associations were analyzed with linear regression models.

Table 3. Levels of calprotectin, CRP and leucocytes in different state of diseases.

Variable	Infectious diseases including pneumonia	COPD	Heart failure
Number of participants	120	183	162
Female (%)	56	62	43
Age at survey (years)	75 (65–86)	72 (64–80)	81 (74–89)
Body mass index (kg/m^2)	25 (22–29)	25 (21–29)	27 (24–30)
Admitted to hospital care (%)	72	56	80
METTS-A (%)
Red	4	5	1
Orange	47	38	54
Yellow	37	32	31
Green	12	25	14
Calprotectin (mg/L)	1.31 (1.72)^a	0.55 (0.77)	0.37 (0.47)
CRP (mg/L)	101 (135.5)^a	8.6 (28.0))	8.3 (17.1)
Leucocytes (10^9/L)	11.9 (6.7)^b	9.9 (4.5)	8.1 (3.2)

^ap < .001 when levels of calprotectin and CRP in patients with infectious diseases including pneumonia were compared to other patient groups; ^bwhen levels of white blood cells in patients with infectious diseases were compared to patients with heart failure.

Data are expressed as median (IQR). Significance was tested using one-way ANOVA.

Table 4. The effect of calprotectin on risk prediction for a severe infection including pneumonia as final diagnose (n = 119).

Logistic regression model variables	AUROC	Asymptotic 95% confidence interval
		Lower bound	Upper bound
Calprotectin	0.78	0.73	0.82
CRP	0.83	0.79	0.87
Body temperature + white blood cells	0.76	0.71	0.80
Body temperature + white blood cells + CRP	0.83	0.79	0.88
Body temperature + white blood cells + CRP + calprotectin	0.83	0.79	0.88