Table 2.

Comparison of the ability of laboratory methods to detect positive Streptococcus equi field samples compared to the direct‐PCR (gold standard)

Laboratory Method	Number Positive	False Positives	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	CC (%)	OR	95% CI	P Value
Direct PCR (gold standard)	35	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref	Ref
Flocked swab PCR	24	0	69	100	100	100	94	1	NA	.001b
Flocked swab culture	13	3a	37	98	81	88	87	30.5	8.6–108.8	<.001
Traditional culture	14	2a	40	99	88	88	88	52	10.8–250.2	<.001

OR, odds ratio; CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value; CC, correctly classified; Ref, referent; NA, not available.

^aTwo of these three values represent the same samples.

^bFisher's exact test, P value for logistic regression model not calculable.