Background: Fecal calprotectin is a reliable noninvasive marker for intestinal inflammation usable for monitoring patients with inflammatory bowel disease. Tests are usually performed by enzyme-linked immunosorbent assay (ELISA), which is time consuming and delays results, thus limiting its use in clinical practice. Our aim was to evaluate CalproSmart, a new rapid test for fecal calprotectin performed by patients themselves at home, and compare it to gold standard ELISA.
Methods: A total of 221 patients with inflammatory bowel disease (115 ulcerative colitis and 106 Crohn's disease) were included. The CalproSmart test involves extraction of feces, application to the lateral flow device, and taking a picture with a smartphone after 10 minutes of incubation. Results appear on the screen within seconds. Patients were instructed at inclusion and had a video guide of the procedure as support. When using CalproSmart at home, patients also sent in 2 fecal samples to be analyzed by ELISA.
Results: Totally, 894 fecal calprotectin results were obtained by ELISA, and 632 of them from CalproSmart. The correlation coefficient was 0.685, higher for academics than nonacademics (0.768 versus 0.637; P = 0.0037). The intra-assay and interassay coefficients of variation of the CalproSmart test were 4.42% and 12.49%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value were 82%, 85%, 47%, and 97%, respectively, with an optimal cutoff at 150 μg/g.
Conclusions: The CalproSmart test performed by patients with inflammatory bowel disease for fast assessment of gut inflammation seems a reliable alternative to ELISA and presents a new way of monitoring patients by eHealth.