Automated interpretation of ANCA patterns - a new approach in the serology of ANCA-associated vasculitis

Table 2 Comparison of manual and automated positive/negative discrimination assessing fluorescence intensity of 342 samples on ethN and formN patterns.

	ethN	Automated interpretation by AKLIDES™
	n (%)	-	+/-	+	++	+++	++++
	-	133 (38.9)	1 (0.3)	0 (0)	0 (0)	0 (0)	0 (0)
	+/-	24 (7.0)	29 (8.5)	12 (3.5)	0 (0)	0 (0)	0 (0)
	+	0 (0)	4 (1.2)	44 (12.9)	11 (3.2)	0 (0)	0 (0)
	++	0 (0)	0 (0)	4 (1.2)	34 (9.9)	9 (2.6)	0 (0)
	+++	0 (0)	0 (0)	0 (0)	3 (0.9)	16 (4.6)	5 (1.5)
	++++	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)	13 (3.8)
Visual interpretation	formN
	n (%)	-	+/-	+	++	+++	++++
	-	225 (65.8)	8 (2.3)	2 (0.6)	2 (0.6)	0 (0)	0 (0)
	+/-	9 (2.6)	22 (6.4)	5 (1.5)	0 (0)	0 (0)	0 (0)
	+	0 (0)	5 (1.5)	25 (7.3)	6 (1.7)	0 (0)	0 (0)
	++	0 (0)	0 (0)	2 (0.6)	20 (5.8)	1 (0.3)	0 (0)
	+++	0 (0)	0 (0)	0 (0)	1 (0.3)	6 (1.7)	0 (0)
	++++	0 (0)	0 (0)	0 (0)	0 (0)	0 (0)	3 (0.9)

ANCA IIF patterns were first interpreted automatically with AKLIDES™ followed by manual reading with a routine fluorescence microscope. Both interpretation methods demonstrated very good agreement on ethN and formN (κ = 0.955, 95% confidence interval (CI): 0.944 to 0.965; κ = 0.929, 95% CI: 0.895 to 0.964; respectively). Quantitative fluorescence intensity threshold values for ethN: < 15 negative (-); ≥ 15 borderline (+/-) < 40; ≥ 40 weak positive (+) < 150; ≥ 150 positive (++) < 400; ≥ 400 strong positive (+++) < 700; ≥ 700 very strong positive (++++). Quantitative fluorescence intensity threshold values for formN: < 20 negative (-); ≥ 20 borderline (+/-) < 30; ≥ 30 weak positive (+) < 100; ≥ 100 positive (++) < 300; ≥ 300 strong positive (+++) < 600; ≥ 600 very strong positive (++++). ANCA, antineutrophil cytoplasmic antibody; ethN, ethanol-fixed neutrophils; formN, formalin-fixed neutrophils; IIF, indirect immunofluorescence.

ISSN: 1478-6362