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Table 3 Screening performance of parallel testing of serum RPR and serum TPPA for S-NS

From: Novel predictors of neurosyphilis among HIV-negative syphilis patients with neurological symptoms: an observational study

Parallel testing format Identification of S-NS Identification of confirmed neurosyphilis Identification of probable neurosyphilis
Sensitivity (%) Specificity (%) NPV (%) Sensitivity (%) Specificity (%) NPV (%) Sensitivity (%) Specificity (%) NPV (%)
RPR≥1:4, TPPA≥1:2560a 87.8 72.5 84.9 97.5 60.8 98.0 70.1 72.5 86.6
RPR≥1:2, TPPA≥1:2560 92.6 55.6 87.6 99.2 45.7 99.1 80.6 55.6 88.4
RPR≥1:4, TPPA≥1:1280 93.1 58.7 89.0 99.2 47.6 99.2 82.1 58.7 89.7
RPR≥1:2, TPPA≥1:1280 95.8 46.4 91.2 100.0 37.0 100.0 88.1 46.4 91.2
  1. S-NS symptomatic neurosyphilis, N-NS syphilis/non-neurosyphilis, RPR rapid plasma reagin, TPPA T. pallidum particle agglutination, PPV positive predictive value, NPV negative predictive value
  2. aA positive screening result was defined as either serum RPR titer ≥1:4 or serum TPPA titer ≥1:2560, or both. And by this analogy