A new rapid home test for Faecal Calprotect in measurement by a mobile phone is reliable

Abstract

Enzyme-linked immunosorbent assay (ELISA) is a quantitative but time consuming method for faecal calprotectin (FC). Two new quantitative rapid tests, Rapid Test (RT) scanning for laboratory use and a Home Test (HT photo) for IBD patients, have recently been developed. To compare the new rapid tests with ELISA, the current ‘Gold Standard’. Quantitative analysis of faecal extracts involved application of a sample onto the ‘Lateral Flow Device’ (LFD). The colour intensity of a test line was read after 10 minutes' incubation using a laptop computer linked to a table-top scanner (RT scanning). A picture taken with a mobile phone (HT photo) of the same LFD was taken and sent to a server via Mobile Internet. The result (FC in mg/kg) appeared on the phone screen after 15 seconds. Specialised software was used for the laptop and mobile phone. Four hundred and four faecal samples were analysed from patients with ulcerative colitis. Mean differences of 1.7 mg/kg (ELISA versus RT scanning), 6.8 mg/kg (ELISA versus HT photo) and 2.9 mg/kg (Rt scanning versus HT photo) were found with good agreement as calculated by kappa statistic (86%, 87% and 95%, respectively). The Coefficients of Variation (CV) for ELISA and HT photo were below 10 %. The HT photo test had a sensitivity of 96.2% and a specificity of 90.1% specificity. The new rapid tests are accurate, and are of utility in clinical settings. Feasibility of the home test as part of disease control and self-management are currently being investigated.