Patient-performed extraction of faecal calprotectin.
Background: Faecal (f-) calprotectin is a widely used marker for intestinal inflammation. However, extraction procedure is time consuming and cumbersome. The main aim of this study was to evaluate patient-performed extraction of f-calprotectin compared to extraction performed in the laboratory.
Methods: A total of 81 adult patients with an established diagnosis of inflammatory bowel disease provided two samples from the same bowel movement, one conventional faeces sample and one sample with a patient administered extraction device. A laboratory technician extracted the conventional faeces sample with the same extraction device.
Results: F-calprotectin results from the laboratory-performed extraction and the patient-performed extraction correlated significantly, with a Spearman rank correlation coefficient of 0.92. Method comparison showed a slope of 1.20 (95% confidence interval 1.08-1.36) with intercept of -0.30 (95% confidence interval -9.00 to 4.62). This demonstrates a small proportional difference between the results from the home extracted samples and the results from the laboratory extracted samples, where the home extracted samples are slightly higher. However, six of the 81 patients had made obvious mistakes in the extraction process and their samples were excluded from the study.
Conclusions: Patient administered extraction of f-calprotectin can be a realistic alternative for selected patients. However, instructions must be very precise to avoid mistakes.