TABLE 3.

Agreement values and kappa coefficient between qPCR and RT-qPCR according to clinical classification and sample type^a,b

	All classifications (possible, probable, proven)	Probable	Probable and proven
All samples
Overall agreement %	85.5 [79.8–89.8]	87.5 [81.1–91.9]	87.8 [81.5–92.1]
Positive agreement %	100.0 [93.8–100.0]	100.0 [92.4–100.0]	100.0 [95.4–100.0]
Negative agreement %	79.3 [71.7–85.2]	81.4 [72.6–87.9]	73.1 [61.5–82.3]
Kappa coefficient	0.69 [0.59–0.79]	0.75 [0.64–0.85]	0.75 [0.64–0.85]
Kappa interpretation	Substantial agreement	Substantial agreement	Substantial agreement
Plasma samples
Overall agreement %	73.2 [60.4–83.0]	76.5 [60.0–87.6]	77.1 [61.0–87.9]
Positive agreement %	NA	NA	NA
Negative agreement %	73.2 [60.4–83.0]	76.5 [60.0–87.6]	77.1 [61.0–87.9]
Kappa coefficient	NA	NA	NA
Kappa interpretation	NA	NA	NA
Respiratory samples
Overall agreement %	92.7 [86.2–96.2]	94.0 [86.7–97.4]	94.0 [86.8–97.4]
Positive agreement %	100.0 [93.2–100.0]	100.0 [91.8–100.0]	100.0 [92.0–100.0]
Negative agreement %	85.7 [74.3–92.6]	87.5 [73.9–94.5]	87.5 [73.9–94.5]
Kappa coefficient	0.85 [0.76–0.95]	0.88 [0.78–0.98]	0.88 [0.78–0.98]
Kappa interpretation	Almost perfect agreement	Almost perfect agreement	Almost perfect agreement

^a For agreement calculation, qPCR method was considered the comparative method and RT-qPCR as the candidate method. Agreements and Kappa coefficient are provided with their 95% confidence intervals [95% CI].

^b NA, not applicable.