Table 2.

Performance of the tag-based real-time locating system and TraceTogether app validated against electronic medical records.^a

Digital contact tracing tool	Sensitivityb	Specificityc	Positive predictive value	Negative predictive value	LR+d	LR−e
Tag-based real-time locating system	96.9% (31/32)	83.1% (103/124)	59.6% (31/52)	99.0% (103/104)	5.73	0.04
TraceTogether app	0.0% (0/32)	98.4% (122/124)	0.0% (0/2)	79.2% (122/154)	0.00	1.02
Either digital contact tracing tool	96.9% (31/32)	81.5% (101/124)	57.4% (31/54)	99.0% (101/102)	5.24	0.04

^aPhysicians 1, 4, 5, 8, 9, 11, 12, and 18 from Table 1 were included in the Table 2 analyses.

^bDenominator for sensitivity = number of patients attended by eight physicians who uploaded their TraceTogether data and had a work shift between 8:30 AM on May 12, 2020 and 8:30 AM on May 13, 2020.

^cDenominator for specificity = number of patients attended by other physicians in the same work shift between 8:30 on May 12, 2020 and 8:30 AM on May 13, 2020.

^dLR+: Positive Likelihood Ratio; LR+ = sensitivity/(1 − specificity).

^eLR−: Negative Likelihood Ratio; LR− = (1 − sensitivity)/specificity.