Background Anti-Sa antibody was identified in 1994 and belongs to a class of antibodies that target citrullinated antigens. Anti-Sa antibody is highly specific for diagnosing rheumatoid arthritis (RA, but it is associated with low prevalence and sensitivity. Anti-RA33 antibody was identified in 1989 and targets RA33 complex or heterogeneous nuclear ribonucleic protein. In contrast to anti-Sa antibody, anti-RA33 antibody does not target citrullinated antigens. Both anti-Sa and anti-RA33 antibodies are considered as specific serological markers for RA. However, studies assessing the diagnostic value of these antibodies in RA have provided inconsistent results.
Objectives The aim of this study is to evaluate the diagnostic performance of anti-Sa and anti-RA33 antibodies in RA.
Methods PubMed, Embase, and Cochrane library databases were searched for relevant studies and 2 meta-analyses were performed to determine the diagnostic accuracy of anti-Sa and anti-RA33 antibodies in patients with RA.
Results The meta-analysis included 17 studies. Of these, 9 studies, which included 1,095 patients and 1,667 controls, were on anti-Sa antibody and 8 studies, which included 905 patients and 835 controls, were on anti-RA33 antibody. Pooled sensitivity and specificity of anti-Sa antibody were 39.5% (95% confidence interval [CI], 36.5–42.4) and 96.8% (95% CI, 95.9–97.4), respectively, and those of anti-RA33 antibody were 31.8% (95% CI, 28.7–35.0) and 90.1% (95% CI, 87.8–92.1), respectively. PLR, NLR, and DOR of anti-Sa antibody were 14.11 (95% CI, 7.076–28.13), 0.607 (95% CI, 0.558–0.703, and 22.76 (95% CI, 11.10–46.69), respectively, and those of anti-RA33 antibody were 3.429 (95% CI, 2.039–5.765), 0.761 (95% CI, 0.681–0.851), and 4.597 (95% CI, 2.602–8.121), respectively. AUC and Q* index for anti-Sa antibody were 0.558 and 0.543, respectively, while those for anti-RA33 antibody were 0.501 and 0.500, respectively.
Conclusions Our meta-analysis indicated that both anti-Sa and anti-RA33 antibodies were highly specific and the PLR of anti-Sa antibody was very useful for diagnosing RA, although they were not sensitive for diagnosing RA.
Disclosure of Interest None declared