TABLE 1.

Area under the receiver-operating characteristic curve, sensitivity, specificity, and predictive values of five serological assays for the diagnosis of R. equi pneumonia in foals^a

Assay	Area under ROC curve (95% CI)	Selected cut-off	Sensitivity (%)	Specificity (%)	Predictive value (%)
					Prevalence 10%		Prevalence 40%
					Positive	Negative	Positive	Negative
ELISA-VapA	0.55a (0.44-0.65)	1:40	81	4	9	66	36	24
		1:80	71	13	8	79	36	40
		1:160	61	30	9	87	37	53
		1:320	56	50	12	41	43	64
		1:640	37	63	10	89	39	60
		1:1,280	24	84	14	90	50	62
		1:2,560	14	96	28	91	69	62
		1:5,120	10	86	7	89	31	59
ELISA-California	0.68b (0.56-0.79)	20%	90	8	10	88	40	56
		30%	83	46	15	97	50	46
		40%	59	88	34	95	76	76
		50%	34	92	31	93	73	68
		60%	7	92	10	90	37	60
ELISA-33701	0.67a,b (0.54-0.78)	0.2	66	4	7	53	31	16
		0.4	44	48	9	88	36	57
		0.7	15	65	4	87	31	53
		1.0	10	83	6	89	27	57
		1.2	5	83	3	89	16	56
ELISA-6939	0.67a,b (0.54-0.78)	0.2	78	61	18	96	58	80
		0.4	39	83	20	92	60	68
		0.7	17	91	18	91	57	62
		1.0	5	96	11	91	43	60
		1.2	5	100	100	90	100	61
Agar gel immunodiffusion	NA	Weak positive	61	58	13	93	49	69
		Positive	44	71	14	91	50	65
		Strong positive	10	92	12	90	45	60

^aWithin a column, assay results with different superscripts were significantly different (P < 0.05). NA, not applicable. CI, confidence interval.