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Table 3 Sensitivity, specificity, predictive values (PPV, NPV) and likelihood ratios +LR, -LR) for the RiboSEQ GBS test and the BD GeneOhm™ StrepB Assay

From: Evaluation of a novel real-time PCR test based on the ssrAgene for the identification of group B streptococci in vaginal swabs

   RiboSEQGBS test BD GeneOhm™ StrepB Assay
   Positive Negative Positive Negative
Culture a Positive 107 4 105 6
  Negative 2 46 5 43
  Sensitivity 96.4% 94.6%
  95% CI (90.5 - 98.8%) (88.1 - 97.8%)
  Specificity 95.8% 89.6%
  95% CI (84.6 - 99.3%) (76.6 - 96.1%)
  PPV b 98.2% 95.5%
  95% CI (92.9 - 99.7%) (89.2 - 98.3%)
  NPV b 92% 87.8%
  95% CI (79.9 - 97.4%) (74.5 - 94.9%)
  +LR b 23.1 9.1
  95% CI (5.9 - 89.9) (3.9 - 20.8)
  -LR b 0.04 0.06
  95% CI (0.01 - 0.1) (0.03 - 0.13)
  1. Calculated using programme available at http://faculty.vassar.edu/lowry/clin1.html
  2. a using culture as the gold standard (n = 159)
  3. b sample population comprised of random (n = 39) and non-random (n = 120) specimens