From:  Diagnostic performance and cutoff optimisation of the CTD Screen assay for ANA detection compared with HEp-2 IFA

 Diagnostic performance of the CTD Screen for common SARDs.

CTD Screen performanceSLESjSSScMCTDOS
Sensitivity (95% CI)76.9%72.5%97.4%87.9%87.9%
Specificity (95% CI)86.5%86.5%86.5%86.5%86.5%
LR+ (95% CI)5.75.47.210.410.4
LR– (95% CI)0.30.30.030.10.1
PPV (95% CI)33.7%49.6%38.5%50.9%50.9%
NPV (95% CI)97.7%94.5%99.7%98.7%98.7%
Accuracy (95% CI)85.7%84.3%87.3%91.2%91.2%
κ (95% CI)0.4000.4960.4940.5980.534
AUC (p-value)0.855 (< 0.001)0.774 (< 0.001)0.957 (< 0.001)0.900 (< 0.001)0.873 (< 0.001)
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95% CI: 95% confidence intervals; AUC: area under the curve; CTD Screen: connective tissue disease Screen; LR: likelihood ratio; MCTD: mixed connective tissue disease; NPV: negative predictive value; OS: overlap syndrome; PPV: positive predictive value; SARD: systemic autoimmune rheumatic disease; SjS: Sjogren’s syndrome; SLE: systemic lupus erythematosus; SSc: systemic sclerosis; κ: Cohen’s kappa.