To estimate the diagnostic accuracy of anti-alpha-fodrin antibodies for primary Sjögren's syndrome (pSS).
Sixty-four pSS subjects and 108 non-pSS patients were prospectively enrolled in this study. Serum anti-alpha-fodrin IgA and IgG were detected by ELISA in a blind fashion. The diagnostic accuracy of anti-alpha-fodrin antibodies was assessed by receiver operating characteristic (ROC) curve analysis. Logistic regression was used to investigate whether anti-alpha-fodrin antibodies could improve the accuracy of pSS diagnosis if used in addition to anti-SSA and anti-SSB.
The areas under the ROC curves for anti-alpha-fodrin IgG and IgA were 0.69 (95% confidence interval (CI): 0.60-0.77) and 0.63 (95% CI: 0.54-0.72), respectively (P < 0.01 for both). The optimal diagnostic thresholds for anti-fodrin IgG and IgA were 11.75 U/ml and 9.75 U/ml, respectively, with a sensitivity of 0.59 and 0.55, and a specificity of 0.75 and 0.73, respectively. Anti-alpha-fodrin IgG and IgA antibodies were associated with pSS after adjustment for anti-SSA and anti-SSB.
Anti-alpha-fodrin IgG and IgA antibodies are useful diagnostic markers which may improve the accuracy of pSS diagnosis.