Accuracy of Urinary AD7c-NTP for Diagnosing Alzheimer's Disease: A Systematic Review and Meta-Analysis

Background: Alzheimer-associated neuronal thread protein (AD7c-NTP) has been reported to have high diagnostic accuracy in patients with Alzheimer's disease (AD). Objective: To determine the diagnostic accuracy of urinary AD7c-NTP for the diagnosis of AD in patients with suspected AD. Methods: We searched MEDLINE (January 1950 to date) and other electronic databases (from inception to date) for diagnostic accuracy studies that compared urinary AD7c-NTP to the standard clinical diagnosis of AD. We conducted citation searches and screened the reference lists of included studies. Studies were assessed for methodological quality using QUADAS. Summary receiver operating characteristic curves were used to summarize overall test performance. Result: Nine studies met our inclusion criteria. The summary estimates of the urinary AD7c-NTP assay for probable or possible AD were as follows: SEN, 0.87 (95% CI: 0.80-0.91); SPE, 0.89 (95% CI: 0.87-0.91); PLR, 8.13 (95% CI: 6.60-10.02); and NLR, 0.15 (95% CI: 0.10-0.22). The four summary estimates of urinary AD7c-NTP assay for probable AD were 0.89 (95% CI: 0.86-0.92), 0.90 (95% CI: 0.88-0.92), 8.88 (95% CI: 7.09-11.12), and 0.12 (95% CI: 0.09-0.16), with no obvious heterogeneity. Conclusion: Urinary AD7c-NTP is a sensitive and specific test for the diagnosis of probable AD. However, whether urinary AD7c-NTP can be used as an early marker is still unknown.