Calprotectin — A Marker of Mortality in COPD? Results from a Prospective Cohort Study

Figures & data

Table 1.  Distribution of variables at baseline stratified by calprotectin

	Calprotectin <100 ng/ml(n = 107)	Calprotectin 100 –200 ng/ml (n = 230)	Calprotectin > 200 ng /ml(n = 123)	P-Value
Age at index date (Years) Median(IQR)	69 (65 –75)	71 (64 –76)	71 (68 –76)	0.27
Charlson Score Index Median (IQR)	2 (1 –2)	2 (1 –2)	2 (1 –3)	0.84
CRP	6.5 (4 –9)	9 (5 –14)	16 (9 –28)	<0.01
Smoking (Years) Median (IQR)	41 (28 –50)	38 (28 –50)	43 (25 –55)	0.60
Neutrophil Granulocyte (x 10^9/L) Median(IQR)*	4.90 (3.90 –6.83)	6.18 (4.88 –7.75)	7.55 (5.66 –9.97)	<0.01
FVC(L) Median (IQR)	1.95 (1.57 –2.48)	2.00 (1.57 –2.47)	1.95 (1.47 –2.36)	0.60
FEV1 (L) Median (IQR)	0.9 (0.71 –1.15)	0.9 (0.69 –1.16)	0.89 (0.67 –1.09)	0.69
FEV1 predicted (%) Median (IQR)	41.44 (32.71 –50.39)	38.35 (29.73 –47.85)	35.81 (28.29 –45.89)	0.06
Long-Term Oxygen Therapy n (%)	5 (4.67)	29 (12.61)	14 (11.38)	0.07
BMI Median(IQR)*	21.74 (19.34 –25.08)	25.03 (21.02 –28.48)	24.64 (21.94 –28.78)	<0.01
Present smokers n (%) **	55 (51.40)	82 (35.65)	77 (62.60)	0.02
Male gender n (%) **	32 (29.91)	124 (53.91)	77 (62.60)	<0.01
Randomization Azithromycin n(%)	47 (43.93)	114 (49.57)	66 (53.66)	0.34

Data is presented as median ± IQR unless otherwise stated. BMI: Body Mass Index;FEV1: forced expiratory volume in 1 second;% pred:% predicted; FVC: forced vital capacity *Significant difference using Kruskal–Wallis equality-of-populations rank test (p < 0.05) ** Significant using Chi-squared test with p < 0.05.

Figure 1.  Survival according to the level of calprotectin. Result of the log rank test is displayed in the lower left corner.

Figure 2.  Survival according to the level of calprotectin stratified on tertiles. Result of the log Rank test for trend is displayed bottom left corner.

Table 2.  Multivariate regression analysis of potential confounders –A multivariate Cox regression was performed to the time period before 1700 days

	Hazard Ratio (95%)	p-Value
Calprotectin < 100 ng/ml	Ref. Value	Ref. Value
Calprotectin 100 –200 ng/ml	1.56 (1.03 –2.38)	0.04
Calprotectin > 200 ng/ml	2.02 (1.27 –3.19)	< 0.01
Age pr. Year above age 50*	1.04 (1.03 –1.06)	< 0.01
Charlson Score Index > 2	1.15 (0.88 –1.50)	0.32
Neutrophil Granulocytes  > = 7.5 × 10^9 Cells/L	1.30 (1.02 –1.65)	0.04
Moderate COPD	Ref. Value	Ref. Value
Severe COPD	1.42 (1.08 –1.89)	0.01
Very Severe COPD	2.04 (1.48 –2.83)	<0.01
Azithromycin vs. Placebo	0.96 (0.77 –1.19)	0.69
Female vs. Male	1.08 (0.85 –1.37)	0.53

COPD: Chronic Obstructive Pulmonary Disease.

*Estimated hazard ratio associated with an increment of one year above 50.

**Moderate COPD (50-79 FEV₁% predicted), Severe COPD (30-50 FEV₁% predicted) and Very Severe COPD (< 30 FEV₁% predicted).

Figure 3.  Scatterplot showing _p-calprotectin against FEV 1% predicted. Spearman correlation coefficient and the calculated p-value are displayed upper left corner.