Cross-sectional evaluation of online direct-to-public calprotectin testing

Abstract

Objective Why about a quarter of patients with inflammatory bowel disease (IBD) suffer symptoms for more than a year before their diagnosis made is unclear. Low public awareness, embarrassment and the apprehension of invasive tests are cited. The anonymity of direct-to-public calprotectin testing may overcome these barriers. We sought to characterise what calprotectin testing is available directly to the public in the UK. Design/method We conducted a cross-sectional evaluation of the calprotectin assays available online in the UK. Collection kits were procured from eligible providers, and surplus stool tested to receive follow-up advice for known positive (>50–100 μg/g) and negative (<50 μg/g) stool samples. Results Half (54.5% (6/11)) of the available tests were home lateral flow tests and the remainder were laboratory-based ELISAs. The lateral flow tests were considerably cheaper than the laboratory-based tests (median (range) cost £14.20 (£7.85–21.00) vs £75.85 (£59–151), p<0.0001). The median turnaround time for the laboratory tests was 14 (range: 1–23) days. All but one provider used a positivity threshold of 50 μg/g. All tests included written and pictorial instructions with the testing kit. Contact with a physician was recommended for similar proportions of positive and negative calprotectin results (54.5% (6/11) vs 54.5% (6/11), p=1). Conclusion In the UK, the public can choose between inexpensive home-based lateral flow tests or send stool samples for gold-standard laboratory testing of calprotectin. The low cost and rapid turnaround times suggest that direct-to-public calprotectin testing could be promoted to try to reduce the time to IBD diagnosis. Data are available upon reasonable request. The data will be made available to investigators whose proposed use of the data has been approved by an independent review committee. Analyses will be restricted to the aims in the approved proposal. Proposals should be directed to Tariq Ahmad (tariq.ahmad1@nhs.net). To gain full access data, requestors will need to sign a data access agreement.