TABLE 2

Estimated disease prevalence and sensitivity and specificity of using serotype-specific qPCR to diagnose VTPPa

Serotype-specific pneumococcal DNA load cutoff value (no. of copies/ml)UAD assayUAD assay + sputum cultureb
Disease prevalence (%)cSensitivity (%)Specificity (%)Youden indexDisease prevalence (%)Sensitivity (%)Specificity (%)Youden index
≥10311.1 (7.4–15.7)81.5 (61.9–93.7)93.5 (89.4–96.4)0.7512.3 (8.4–17.1)83.3 (65.3–94.4)94.9 (91.0–97.4)0.782
≥10481.5 (61.9–93.7)94.5 (90.5–97.1)0.7683.3 (65.3–94.4)95.9 (92.2–98.1)0.792
≥10574.1 (53.7–88.9)95.4 (91.7–97.8)0.69576.7 (57.7–90.1)96.7 (93.4–98.7)0.734
≥10670.4 (49.8–86.2)97.7 (94.7–99.2)0.68170.0 (50.6–85.3)98.6 (96.0–99.7)0.686
≥10763.0 (42.4–80.6)98.2 (95.3–99.5)0.61263.3 (43.9–80.1)99.1 (96.6–99.9)0.624
≥10851.9 (31.9–71.3)99.1 (96.7–99.9)0.5146.7 (28.3–65.7)99.1 (96.6–99.9)0.458
≥10922.2 (8.6–42.3)99.1 (96.7–99.9)0.21320.0 (7.7–38.6)99.1 (96.7–99.9)0.191
  • a qPCR, quantitative PCR; UAD, serotype-specific urinary antigen detection assay. Values in parentheses are 95% confidence intervals.

  • b Determined by conventional sputum culture and by use of the Quellung reaction's bacterial load cutoff value of 1.0 × 105 CFU/ml.

  • c Estimated from the reference standard or the composite reference standard result assuming 100% specificity.