Published online Jan 14, 2020. doi: 10.3748/wjg.v26.i2.246
Peer-review started: November 1, 2019
First decision: November 22, 2019
Revised: December 19, 2019
Accepted: January 2, 2020
Article in press: January 2, 2020
Published online: January 14, 2020
Processing time: 72 Days and 17.9 Hours
Non-invasive criteria are needed for Crohn’s disease (CD) diagnosis, with several biomarkers being tested, including the pancreatic autoantibodies-to-glycoprotein-2 (anti-GP2).
Results of individual diagnostic test accuracy (DTA) studies assessing the diagnostic value of the anti-GP2 for the diagnosis of CD appear promising, however, a systematic review and meta-analysis of the studies is still lacking.
The aim of the present systematic review and meta-analysis was synthesize all evidence on the diagnostic accuracy of anti-GP2 tests in patients with suspected/confirmed CD.
An electronic search was conducted on Medline, Cochrane-CENTRAL and grey literature. Quality was assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool and hierarchical models were employed to synthesize the data. The hierarchical summary receiver operating characteristic (HSROC) model was employed to synthesize data. SROC curves were constructed and since a summary point of sensitivity or specificity with studies using mixed thresholds would be clinically uninterpretable, the summary sensitivity was estimated at its median specificity, based on the SROC curves. Heterogeneity was assessed statistically by including covariates in the HSROC model (meta-regression) and was summarized with the Relative Diagnostic Odds Ratios.
Out of 722 studies retrieved, 15 were meta-analyzed. Thirteen studies had industry-related conflicts-of-interest, and most included healthy donors as controls. For the combination of IgA and/or IgG anti-GP2 test, the summary sensitivity was 20% at a median specificity of 97%.
The anti-GP2 demonstrated low sensitivity and high specificity. These results indicate caution before relying on its diagnostic value. However, the anti-GP2 appear to attain all characteristics of a screening tool rather than a diagnostic one. Therefore, based on the available evidence, the use of the anti-GP2 for CD diagnosis is not warranted. Furthermore, overall quality of DTA studies appears low, with many carrying industry-related, spectrum, test-review and partial verification bias. Thus, the need for improving the methodology of DTA studies is evident.
The majority of DTA studies are lacking a quality design and should be synthetized with caution. Future research should assess differences between industry-funded and non-industry funded DTA studies.