Table 2.

Comparison of Methods for Detection of CDI in Patients with Symptoms

Diagnostic method	No. true positive	No. false positive	No. false negative	No. true negative	Invalid results⁎, %	Sensitivity†		Specificity		Predictive value, %		Youden index, %
						%	95% CI	%	95% CI	Positive	Negative
GeneOhm Cdiff assay	25	0	1	55	4.0	96.2	88.0–96.2	100	96.1 to 100	100	98.2	96.2
Xpert C. difficile test	25	2	1	53	1.1	96.2	86.0–99.2	96.4	91.6 to 97.8	92.6	98.1	92.5
ProGastro Cd assay	23	0	3	55	0	88.5	79.3–88.5	100	95.6 to 100	100	94.8	88.5
Quik Chek Complete‡	16	0	10	55	NA	61.5	51.4–61.5	100	95.2 to 100	100	84.6	61.5
GDH/EIA§	11	0	15	55	NA	42.3	32.4–42.3	100	95.3 to 100	100	78.6	57.7

Eighty-one specimens were analyzed using all methods.

CDI, Clostridium difficile infection; CI, confidence interval; NA, not applicable.

^⁎Xpert demonstrated an additional 5.5% “error rate.” At repeat testing, 100% of invalid specimens and errors for both GeneOhm and Xpert were resolved and provided definitive results, which are included in the total.

^†P < 0.03 for all molecular methods versus nonmolecular methods; Quik Chek Complete versus GDH/EIA was not significant.

^‡GDH component was 96.2% sensitive and 81.8% specific.

^§GDH component was 96.2% sensitive and 76.4% specific.