Performance of seven commercial automated assays for the detection of low levels of anti-Toxoplasma IgG in French immunocompromised patients

Open Access

Table 3

Relative sensitivity, specificity, PPV, and NPV by testing 82 positive and 272 negative samples for anti-toxoplasma IgG.^a

Immunoassay and classification of equivocal result	Sensitivity^b (%) [95% CI]	Specificity^b (%) [95% CI]	PPV^c (%)	NPV^c (%)
Elecsys/Cobas 8000
Positive	100 [100–100]	85.7 [82.0–89.3]	76.1	100
Negative	73.2 [68.7–77.8]	99.3 [98.4–100]	97.8	89.0
Architect/i2000
Positive	43.9 [38.7–49.1]	100 [100–100]	100	79.6
Platelia/Evolis
Positive	36.6 [31.6–41.6]	100 [100–100]	100	77.6
Negative	32.9 [28.0–37.8]	100 [100–100]	100	76.6
Access II/Access
Positive	32.9 [28.0–37.8]	99.3 [28.4–100]	95.3	76.5
Negative	13.4 [9.7–17.0]	99.6 [99–100]	94.3	71.6
TGS TA/IDS-iSYS
Positive/Negative	46.3 [41.1–51.5]	96.7 [94.8–98.6]	86.4	79.8
Vidas II/Mini Vidas
Positive	37.8 [32.7–42.9]	100 [100–100]	100	77.9
Negative	12.2 [8.8–15.6]	100 [100–100]	100	71.4
Liaison II/Liaison XL
Positive	13.4 [9.7–17.0]	100 [100–100]	100	71.7
Negative	11.0 [7.7–14.2]	100 [100–100]	100	71.1

PPV, positive predictive value; NPV, negative predictive value.

The criteria were determined with the high and low cut-off values specified by the manufacturers. The confirmatory test was the Toxo II IgG Western blot (LDBio).

Performance values were calculated using the Toxo II IgG test Western blot as the reference test.

PPVs and NPVs were calculated using an estimated seroprevalence in France (31.3%).

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