Specificity and sensitivity of aquaporin 4 antibody detection tests in patients with neuromyelitis optica: A meta-analysis

Objective Antibodies against water channel protein aquaporin 4 (AQP4) in astrocytes play a role in the etiology and physiopathology of neuromyelitis optica (NMO); detection of this immunoglobulin in serum is highly suggestive of this diagnosis. There are several immunoassays to detect the antibody with different sensitivities and specificities. We conducted a meta-analysis to determine the overall diagnostic accuracy from these tests. Methods We conducted a systematic review in five different electronic databases: Pubmed, Embase, The Cochrane Library, Scopus, Database of Abstracts of Reviews of Effect (DARE) and Lilacs. We included both case control and consecutive enrollment studies that evaluated the performance of the immunoassays in patients with suspected NMO in comparison with the 2006 Wingerchuk diagnostic criteria. Articles were assessed by two different reviewers, who also extracted data. Results 30 studies for three different immunoassays were included in the meta-analysis. To obtain a summary estimate for the sensitivity and specificity with 95% confidence interval a bivariate random effect model was used. The approximated sensitivity for the cell based assay (CBA), the tissue-based assay (TBA) and the ELISA test were 0.76(95% CI 0.67-0.82), 0.59(95% CI 0.50-0.67), and 0.65(95% CI 0.53-0.75) respectively. The mean specificity of the CBA was 0.99 (95% CI 0.97-0.99), TBA 0.98 (95% CI 0.97-0.99) and ELISA 0.97(95% CI 0.96-0.99). Conclusions AQP4 detection in serum with immunoassay is a great tool for the diagnosis of patients with NMO, due to the high specificity, allowing the clinician to differentiate this disease from other neurological conditions that resemble NMO.