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* = Presenting author

DOP067 Faecal calprotectin measurements by IBD patients themselves at home are feasible and provide reliable Results compared to the standard lab method.

K. Kofod Vinding*1, H. Elsberg1, T. Thorkilgaard1, D. Marker1, N. Pedersen1, K. Carlsen1, J. Burisch1, P. Munkholm2

1Herlev Hospital, Gastrounit, medical section (54R1M), Herlev, Denmark, 2University of Copenhagen, Clinical Medicine, Copenhagen, Denmark

Background

Faecal calprotectin (FC) is a reliable biomarker for assessing disease activity in IBD patients. Current detection Methods, however, are time-consuming and patients wait up until 14 days for the result, limiting the use in clinical decision making. CalproSmart ™ is a test for FC performed by the patients themselves in their own home with a result in minutes. The aim of this study was to compare CalproSmart in the hands of patients with the gold standard; enzyme-linked immunosorbent assay (ELISA) in the lab.

Methods

As part of an eHealth trial, consecutive patients in remission or with mild-moderate active disease measured their FC levels monthly using CalproSmart. From the same stool, patients also send in a sample to the lab where ELISA is used for detection of FC CalproSmart consists of an extraction container with prefilled extraction buffer and a dosing tip and a lateral flow cassette containing antibodies against calprotectin at a control line and a test line. Using a designated smartphone app, the patient takes a picture and the ratio between the staining intensity of the two lines is calculated. The procedure takes about 25 minutes.

Correlation between ELISA and CalproSmart was calculated as well as sensitivity, specificity, negative and positive predictive values (NPV, PPV) with a pre-defined cut-off of 200 mg/kg FC as per protocol of the eHealth trial. We assessed the sample-to-sample and the sample-within-sample reproducibility of the CalproSmart test.

Results

In total 221 patients were included into the study (115 UC, 106 CD, median age 49, range 20-85 years, 60 % females). 894 faecal samples were analysed by ELISA, while 638 tests were performed at home by patients using CalproSmart. In total 1078 FC Results were eligible for Spearman's rank correlation analysis, resulting in rho = 0.685, p < 0.0001).

The coefficient of variability for the within-sample reproducibility of CalproSmart was 4.42% (mean±SD:276 ± 13, range 110-600 µg/g). The coefficient of variability for the sample-to-sample reproducibility was 10.90% (mean±SD: 292 ± 34 µg/g, range 0-600 µg/g). With a cut-off of FC at 200 µg/g to predict relapse, the sensitivity, specificity, NPP and PPV were 0.88, 0.76, 0.53 and 0.96 respectively.

Conclusion

For the first time, patients themselves are able to measure their FC levels with immediate response. CalproSmart shows strong positive relationship with the gold standard. The coefficients of variability are acceptably low and with a cut-off at 200 µg/g, the sensitivity and PPV are high. The tool allows for fast and reliable assessment of gut inflammation by the patient themselves, thereby constituting a valuable addition to clinical decision making by physicians and patients.