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

Figures

Figure 1.
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.
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.

Tables

Table 1. Evaluation of the Stability of the Fecal Extracts in Different Fecal Calprotectin Tests
 
TestMethodExtraction device-20 °C2 - 8 °CRoom 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 immunochromatographyRALNENENE
CalDetect test 50/200 (Preventis GmbH Bensheim, Germany)Semi-quantitative immunochromatographyPreventisNE7 daysNE
Calfast (Eurospital, Trieste, Italy)Quantitative immunochromatographyEurospital3 months2 daysNE
Calprotectin turbo (Buhlmann, Schonenbuch, Switzerland)Turbidimetric immunoassaySmart-Prep
Buhlmann
> 24 months7 daysNE
Calprotectin ELISA (Buhlmann, Schonenbuch, Switzerland)EnzymoimmunoassayCalex Cap BuhlmannNENE3 days
Quantitative Fecal Calprotectin (DIASource, Ottignies-Louvain-la-Neuve, Belgium)EnzymoimmunoassayDIASourceLong period*3 daysDuring transport*
Calpro EasyExtract™ (Calpro AS, Lysaker, Norway)EnzymoimmunoassayCalpro AS6 months> 5 days5 days
Calprolab™HRP (Calpro AS, Lysaker, Norway)EnzymoimmunoassayRoche> 24 months> 5 daysNE
Elia Calprotectin (Thermo Fisher, Uppsala, Sweden)FluoroenzymoimmunoassayRoche3 monthsNot recommended**NE
LIAISON® Calprotectin (DIASorin, Saluggia, Italy)Chemiluminescent immunoassayLIAISON DIASorinNot recommended7 days4 h

 

Table 2. Fecal Calprotectin Results (in µg/g Stools) in Different Diagnostic Groups
 
DiseaseC/T-F, nC, rangeT-F, rangeC, medianT-F, medianCT-F
mean95% CImean95% CI
n: sample numbers; C/T-F: both methods; C: Calpro AS; T-F: Thermo Fisher. IBD: inflammatory bowel disease.
IBD555 - 2,17915 - 4,247233221587393 - 781419236 - 603
Crohn’s disease245 - 1,71315 - 1,796156179428183 - 674309138 - 481
Ulcerative colitis317.5 - 2,17915 - 4,247338259709421 - 998514209 - 801
Non-IBD organic diseases365 - 1,30415 - 1,1576560390154 - 614264142 - 431
Functional disorders1075 - 19515 - 25710162519 - 324231 - 53

 

Table 3. Stratification of the Fecal Calprotectin Results (in µg/g Stools)
 
Calpro ASThermo Fisher
123Total
1: 0 - 49; 2: 50 - 100; 3: > 100. *Matching results by both methods.
1104*38115
272*918
31559*65
Total1121076198

 

Table 4. Test Performance of the Fecal Calprotectin Assays With Two Cut-Off Values
 
Calpro ASThermo FisherCalpro ASThermo Fisher
Fecal calprotectin cut-off (µg/g)5050100100
Sensitivity (%)78.281.867.374.5
Specificity (%)74.868.883.275.5
Accuracy (%)77.269.779.375.3
Positive predictive value (%)53.851.161.353.9
Negative predictive value (%)90.290.587.588.5
Positive likelihood ratio (%)2.92.64.13.1
Negative likelihood ratio (%)0.290.430.370.34