Table 4.

Diagnostic performance of conventional methods and the multiplex PCR-based assay and using conventional methods, final clinical diagnosis of empyema, empyema and pleura fluid ≤7.2 as reference-standard

1. All cases – Conventional methods as reference-standard	Sensitivity (%)	Specificity (%)	Positive predictive value (%)
Multiplex PCR-based assay vs. all pathogens	12	93.5	20
Multiplex PCR-based assay vs. only panel pathogens	67	93.7	13
2. Using cases with final clinical diagnosis of empyema - conventional methods as reference-standard	Sensitivity	Specificity
Multiplex PCR-based assay vs. all pathogens	15.8	80	27
Multiplex PCR-based assay vs. only panel pathogens	100	84.2	18
3. Using cases with or without empyema diagnosis as reference-standard	Sensitivity	Specificity
Conventional methods (all pathogens)	32.8	96.1	77
Conventional methods only panel pathogens	3.3	99.3	67
Multiplex PCR-based assay	18.6	97.3	73
4. Using cases with or without pleural fluid pH ≤ 7.2 as reference standard	Sensitivity	Specificity
Conventional methods (all pathogens)	37.8	95.8	70
Conventional methods only panel pathogens	2.7	99.3	100
Multiplex PCR-based assay	13.5	97.1	56