. 2014 Aug 4;59(10):1353–1360. doi: 10.1093/cid/ciu620

Table 4.

Hypothetical Impact of Xpert Assay on Time to Testing Completion and Duration of Respiratory Isolation Among Patients With Negative Tuberculosis Cultures (n = 133)

Impact	Smear Microscopy Strategy^a	Concentrated Xpert Strategy^b	Direct Xpert Strategy^c
Time to result, h, median (IQR)	66 (58–85)	34 (28–53)	4.5 (2.9–10)
Time savings vs microscopy, h, median (IQR)^d	…	35 (24–36)	45 (35–46)
Total time in isolation, days/y (95% CI)	840 (116–1564)	684 (0–1410)	35 (31–39)
Total time savings vs control, days/y (95% CI)	…	159 (75–242)	258 (227–288)

Abbreviations: AFB, acid-fast bacilli; CI, confidence interval; IQR, interquartile range; smear, AFB smear microscopy; Xpert, GeneXpert MTB/RIF assay.

^a Collection of 2 sputum samples on separate days for N-acetyl-l-cysteine–sodium hydroxide (NALC-NaOH) concentrated acid-fast bacilli smear microscopy.

^b Collection of 1 sputum sample for processing using NALC-NaOH concentration and testing by Xpert.

^c Collection of 1 sputum sample for direct testing by Xpert.

^d Savings reflect within-patient differences and are not equal to differences between medians for each strategy.