Table 2.

Accuracy of various diagnostic tests for FIP

Category	Test Type	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	Prevalence (%)	Ref.
Protein analysis	Total protein ≥8 g/dl	57	64	76	43	67	138, 143a
	Gamma-globulin ≥2.5 g/dl	70	86	90	61	65	143
	A:G ratio
	≤0.8	80	82	92	61	72	143
	<0.45	25	98	64	90	13	139
	Protein electrophoresis	38	50	60	29	67	144
	α1-Acid glycoprotein levels >1.5	85	100	100	75	70	192
Effusion analysis	Total protein >3.5 g/dl	87	60	77	71	72	142
	Gamma-globulin ≥1.0 g/dl	82	83	84	80	53	143
	A:G ratio
	≤0.9	86	74	79	82	53	143
	≤0.5	62	89	86	68	53	143
	Rivalta test	98	80	84	97	51	143
	Presence of antibodies	86	85	86	85	51	143
	Cytology suggestive of FIP	90	71	89	73	72	142
	Antigen staining in macrophages	72	100	100	68	62	142, 143, 193a
Serology	IFA (any titer)	85	57	44	90	28	143
	IFA (titer >1,600)	67	98	94	88	28	143
	ELISA	100	93	94	100	53	155, 187,a
	Antigen–antibody complex	48	91	67	84	26	143
Viral nucleic acid detection	Nested RT-PCR
	Serum	55	88	90	48	67	143, 163,a
	Effusion	96	92	96	92	63	143, 162, 163,a
	mRNA RT-PCR
	Blood	94	92	67	92	15	168, 169, 170,a

Abbreviations: A:G ratio, albumin to globulin ratio; ELISA, enzyme-linked immunosorbent assay; IFA, immunofluorescent antibody assay; mRNA, messenger RNA; NPV, negative predictive value; PPV, positive predictive value; RT-PCR, reverse transcriptase polymerase chain reaction.

^aCalculated based on concatenated data from original studies.