Antiphospholipase A₂ Receptor Autoantibodies: A Comparison of Three Different Immunoassays for the Diagnosis of Idiopathic Membranous Nephropathy

Table 1

Qualitative agreements between the different methods.

All IMN and NC patients (𝑛=198)	IFA-CBA			Percent agreement (95% confidence)
	Positive	Negative	Total
ELISA
Positive	83	10	93	Pos. agreement = 82.2% (73.3–89.1%)
Negative	18	87	105	Neg. agreement = 89.7% (81.9–94.9%)
Total	101	97	198	Total agreement = 85.9% (80.2–90.4%)
kappa = 0.72 (95% CI 0.62–0.81)
All IMN and NC patients (𝑛=198)	IFA-CBA			Percent Agreement (95% confidence)
	Positive	Negative	Total
ALBIA
Positive	100	6	106	Pos agreement = 99.0% (94.6–100.0%)
Negative	1	91	92	Neg agreement = 93.8% (87.0–97.7%)
Total	101	97	198	Total agreement = 96.5% (92.9–98.6%)
kappa = 0.93 (95% CI 0.88–0.98)
All IMN and NC patients (𝑛=198)	ELISA			Percent agreement (95% confidence)
	Positive	Negative	Total
ALBIA
Positive	83	23	106	Pos agreement = 89.2% (81.1–94.7%)
Negative	10	82	92	Neg agreement = 78.1% (69.0–85.6%)
Total	93	105	198	Total agreement = 83.3% (77.4–88.2%)
kappa = 0.67 (95% CI 0.57–0.77)