Multicenter Evaluation of NeuMoDx Group B Streptococcus Assay on the NeuMoDx 288 Molecular System

DOI: 10.1128/JCM.01324-18

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FIG 1
NeuMoDx 288 system.
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FIG 2
Diagram of workflow for NeuMoDx method comparison study.

TABLE 1

Results of prospective sample testing at each laboratory site

Site	No. of samples that were:				Total	% (95% CI)
Site	True positive	False positive	True negative	False negative	Total	Sensitivity	Specificity	Total agreement
A	73	9	263	6	351	92.4 (84.4–96.5)	96.7 (93.8–98.3)	95.7 (91.1–99.4)
B	62	19	318	1	400	98.4 (91.5–99.7)	94.4 (91.4–96.4)	95.0 (91.1–98.0)
C	118	9	314	1	442	99.2 (95.4–99.9)	97.2 (94.8–98.5)	97.7 (93.3–101.4)
Total	253	37	895	8	1,193	96.9 (94.1–98.4)	96.0 (94.6–97.1)	96.2 (93.8–98.3)

TABLE 3

Combined results of interlaboratory reproducibility study^a

GBS sample panel concentration	Agreement type	Performance requirement (%)	NeuMoDx
GBS sample panel concentration	Agreement type	Performance requirement (%)	% agreement	95% CI
Moderate-positive samples (4× LOD, 95% CI upper limit)	Positive (PPA)	>99	100 (75/75)	95.1–100
Low-positive samples (1.5× LOD, 95% CI upper limit)	Positive (PPA)	>95	97.3 (73/75)	90.8–99.3
Low-negative samples (1:100 dilution of 1× LOD, 95% CI upper limit)	Negative (NPA)	>95	98.7 (74/75)	92.8–99.8)
Negative samples (no target present)	Negative (NPA)	∼100	100 (75/75)	95.1–100

↵a The lower and upper limits of the 95% CI were calculated using 95% CI method according to CLSI-approved guideline EP12-A2. LLOD, lower limit of detection; PPA, positive percent agreement; NPA, negative percent agreement.