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Table 3 RDT performances compared to various parameters on 196 and 133 undiluted and 1:100-diluted specimens, respectively

From: Strategy using a new antigenic test for rapid diagnosis of Streptococcus pneumoniae infection in respiratory samples from children consulting at hospital

RDT resultsS. pneumoniae positive culture
PositiveNegativeSensitivity
% (IC 95%)
Specificity
% (IC 95%)
PPV
% (IC 95%)
NPV
% (IC 95%)
RDT undiluted  100 (94.8–100)50.4 (41.4–58.6)52.6 (48.3–56.9)100 (94.3–100)
 Positive7063    
 Negative063    
RDT diluted  91.4 (82.5–96)80.9 (69.6–88.7)84.2 (76.1–89.9)89.5 (79.8–94.9)
 Positive6412    
 Negative651    
 S. pneumoniae culture ≥107 CFU/ml
PositiveNegativeSensitivity
% (IC 95%)
Specificity
% (IC 95%)
PPV
% (IC 95%)
NPV
% (IC 95%)
RDT undiluted  100 (92.9–100)43.1 (35.4–51.2)37.6 (34.3–41)100 (94.3–100)
 Positive5083    
 Negative063    
RDT diluted  94.6 (92.9–100)68.7 (58.1–77.4)65.8 (58.3–72.6)100 (93.7–100)
 Positive5026    
 Negative057    
 Quantitative PCR for ply gene Ct < 22
PositiveNegativeSensitivity
% (IC 95%)
Specificity
% (IC 95%)
PPV
% (IC 95%)
NPV
% (IC 95%)
RDT undiluted  98.4 (91.5–99.7)46.6 (38.3–55.1)46.6 (42.7–50.7)98.4 (89.8–99.8)
 Positive6271    
 Negative162    
RDT diluted  91.9 (82.5–96.5)73.2 (61.9–82.1)75 (67–81.6)91.2 (82–96)
 Positive5719    
 Negative552    
 Quantitative PCR for lytA gene Ct < 23
PositiveNegativeSensitivity
% (IC 95%)
Specificity
% (IC 95%)
PPV
% (IC 95%)
NPV
% (IC 95%)
RDT undiluted  100 (87.5–100)37.3 (30.3–44.8)20.3 (18.5–22.3)100 (94.3–100)
 Positive27106    
 Negative063    
RDT diluted  96.3 (81.7–99.3)52.8 (43.4–62.1)34.2 (29.6–39.2)98.3 (89–99.7)
 Positive2650    
 Negative156    
 S. pneumoniae pneumonia
PositiveNegativeSensitivity
% (IC 95%)
Specificity
% (IC 95%)
PPV
% (IC 95%)
NPV
% (IC 95%)
RDT undiluted  100 (85.7–100)36.4 (29.6–43.8)17.3 (15.7–19)100 (94.3–100)
 Positive23110    
 Negative063    
RDT diluted  100 (85.7–100)51.8 (42.6–60.9)30.3 (26.3–34.5)100 (93.7–100)
 Positive2353    
 Negative057    
  1. PPV positive predictive value, NPV negative predictive value