J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 10, Number 5, May 2018, pages 396-404

Fecal Calprotectin: A Comparison of Two Commercial Enzymoimmunoassays and Study of Fecal Extract Stability at Room Temperature

Figure 1. Comparative studies between both assays. (a) Passing-Bablok adjusted scatter plot of the fCal results obtained by Calpro AS vs. Thermo Fisher. Regression equation: y = -9.88 (95% CI (-12.55 to -6.18)) + 1.19 × (95% CI (1.00 to 1.34)). Significance level: P < 0.0001. (b) Plot of differences (Bland-Altman) between Calpro AS and Thermo Fisher vs. the mean of the two measurements. (c) Histogram of differences between the two methods.

Figure 2. Comparative study between recent fecal extracts and extracts after 4 days at room temperature. (a) The Passing-Bablok scatter plot of fCal results in recent fecal extracts and after 4 days at room temperature, determined by Calpro AS. Regression equation: y = 0.24 (95% CI (-0.44 to 0.89)) + 1.15 × (95% CI (1.08 to 1.21)). Significance level: P < 0.0001. (b) Bland-Altman diagram between the values of recent fCal extracts and after 4 days at room temperature. (c) Histogram of differences between the two measurements.

**Table 1.** Evaluation of the Stability of the Fecal Extracts in Different Fecal Calprotectin Tests
Test	Method	Extraction device	-20 °C	2 - 8 °C	Room temperature
NE: not evaluated by the manufacturer. Number of days not specified. *May lead to decreases in fecal calprotectin concentration.
Quick Check Gernon (RAL, Barcelona, Spain)	Qualitative immunochromatography	RAL	NE	NE	NE
CalDetect test 50/200 (Preventis GmbH Bensheim, Germany)	Semi-quantitative immunochromatography	Preventis	NE	7 days	NE
Calfast (Eurospital, Trieste, Italy)	Quantitative immunochromatography	Eurospital	3 months	2 days	NE
Calprotectin turbo (Buhlmann, Schonenbuch, Switzerland)	Turbidimetric immunoassay	Smart-Prep Buhlmann	> 24 months	7 days	NE
Calprotectin ELISA (Buhlmann, Schonenbuch, Switzerland)	Enzymoimmunoassay	Calex Cap Buhlmann	NE	NE	3 days
Quantitative Fecal Calprotectin (DIASource, Ottignies-Louvain-la-Neuve, Belgium)	Enzymoimmunoassay	DIASource	Long period*	3 days	During transport*
Calpro EasyExtract™ (Calpro AS, Lysaker, Norway)	Enzymoimmunoassay	Calpro AS	6 months	> 5 days	5 days
Calprolab™HRP (Calpro AS, Lysaker, Norway)	Enzymoimmunoassay	Roche	> 24 months	> 5 days	NE
Elia Calprotectin (Thermo Fisher, Uppsala, Sweden)	Fluoroenzymoimmunoassay	Roche	3 months	Not recommended**	NE
LIAISON^® Calprotectin (DIASorin, Saluggia, Italy)	Chemiluminescent immunoassay	LIAISON DIASorin	Not recommended	7 days	4 h

Table 1. Evaluation of the Stability of the Fecal Extracts in Different Fecal Calprotectin Tests

Test

Method

Extraction device

-20 °C

2 - 8 °C

Room temperature

NE: not evaluated by the manufacturer. *Number of days not specified. **May lead to decreases in fecal calprotectin concentration.

Quick Check Gernon (RAL, Barcelona, Spain)

Qualitative immunochromatography

RAL

CalDetect test 50/200 (Preventis GmbH Bensheim, Germany)

Semi-quantitative immunochromatography

Preventis

7 days

Calfast (Eurospital, Trieste, Italy)

Quantitative immunochromatography

Eurospital

3 months

2 days

Calprotectin turbo (Buhlmann, Schonenbuch, Switzerland)

Turbidimetric immunoassay

Smart-Prep
Buhlmann

> 24 months

7 days

Calprotectin ELISA (Buhlmann, Schonenbuch, Switzerland)

Enzymoimmunoassay

Calex Cap Buhlmann

3 days

Quantitative Fecal Calprotectin (DIASource, Ottignies-Louvain-la-Neuve, Belgium)

Enzymoimmunoassay

DIASource

Long period*

3 days

During transport*

Calpro EasyExtract™ (Calpro AS, Lysaker, Norway)

Enzymoimmunoassay

Calpro AS

6 months

> 5 days

5 days

Calprolab™HRP (Calpro AS, Lysaker, Norway)

Enzymoimmunoassay

Roche

> 24 months

> 5 days

Elia Calprotectin (Thermo Fisher, Uppsala, Sweden)

Fluoroenzymoimmunoassay

Roche

3 months

Not recommended**

LIAISON^® Calprotectin (DIASorin, Saluggia, Italy)

Chemiluminescent immunoassay

LIAISON DIASorin

Not recommended

7 days

4 h

**Table 2.** Fecal Calprotectin Results (in µg/g Stools) in Different Diagnostic Groups
Disease	C/T-F, n	C, range	T-F, range	C, median	T-F, median	C	T-F
n: sample numbers; C/T-F: both methods; C: Calpro AS; T-F: Thermo Fisher. IBD: inflammatory bowel disease.
IBD	55	5 - 2,179	15 - 4,247	233	221	587	393 - 781	419	236 - 603
Crohn’s disease	24	5 - 1,713	15 - 1,796	156	179	428	183 - 674	309	138 - 481
Ulcerative colitis	31	7.5 - 2,179	15 - 4,247	338	259	709	421 - 998	514	209 - 801
Non-IBD organic diseases	36	5 - 1,304	15 - 1,157	65	60	390	154 - 614	264	142 - 431
Functional disorders	107	5 - 195	15 - 257	10	16	25	19 - 32	42	31 - 53

Table 2. Fecal Calprotectin Results (in µg/g Stools) in Different Diagnostic Groups

Disease

C/T-F, n

C, range

T-F, range

C, median

T-F, median

T-F

mean

95% CI

mean

95% CI

n: sample numbers; C/T-F: both methods; C: Calpro AS; T-F: Thermo Fisher. IBD: inflammatory bowel disease.

IBD

5 - 2,179

15 - 4,247

233

221

587

393 - 781

419

236 - 603

Crohn’s disease

5 - 1,713

15 - 1,796

156

179

428

183 - 674

309

138 - 481

Ulcerative colitis

7.5 - 2,179

15 - 4,247

338

259

709

421 - 998

514

209 - 801

Non-IBD organic diseases

5 - 1,304

15 - 1,157

390

154 - 614

264

142 - 431

Functional disorders

107

5 - 195

15 - 257

19 - 32

31 - 53

**Table 3.** Stratification of the Fecal Calprotectin Results (in µg/g Stools)
Calpro AS	Thermo Fisher
1: 0 - 49; 2: 50 - 100; 3: > 100. *Matching results by both methods.
1	104*	3	8	115
2	7	2*	9	18
3	1	5	59*	65
Total	112	10	76	198

Table 3. Stratification of the Fecal Calprotectin Results (in µg/g Stools)

Calpro AS

Thermo Fisher

Total

1: 0 - 49; 2: 50 - 100; 3: > 100. *Matching results by both methods.

104*

115

59*

Total

112

198

**Table 4.** Test Performance of the Fecal Calprotectin Assays With Two Cut-Off Values
	Calpro AS	Thermo Fisher	Calpro AS	Thermo Fisher
Fecal calprotectin cut-off (µg/g)	50	50	100	100
Sensitivity (%)	78.2	81.8	67.3	74.5
Specificity (%)	74.8	68.8	83.2	75.5
Accuracy (%)	77.2	69.7	79.3	75.3
Positive predictive value (%)	53.8	51.1	61.3	53.9
Negative predictive value (%)	90.2	90.5	87.5	88.5
Positive likelihood ratio (%)	2.9	2.6	4.1	3.1
Negative likelihood ratio (%)	0.29	0.43	0.37	0.34

Table 4. Test Performance of the Fecal Calprotectin Assays With Two Cut-Off Values

Calpro AS

Thermo Fisher

Calpro AS

Thermo Fisher

Fecal calprotectin cut-off (µg/g)

100

Sensitivity (%)

78.2

81.8

67.3

74.5

Specificity (%)

74.8

68.8

83.2

75.5

Accuracy (%)

77.2

69.7

79.3

75.3

Positive predictive value (%)

53.8

51.1

61.3

53.9

Negative predictive value (%)

90.2

90.5

87.5

88.5

Positive likelihood ratio (%)

2.9

2.6

4.1

3.1

Negative likelihood ratio (%)

0.29

0.43

0.37

0.34