Table 1:

Confusion matrix comparing the machine-learning algorithm to the reviewer confirmation of Anatomic Therapeutic Chemical–coded antibiotic medications in the Canadian Primary Care Sentinel Surveillance Network database

CPCSSN algorithm	Human review; no. of records
CPCSSN algorithm	Yes (antibiotic)	No (not an antibiotic)
Yes (antibiotic)	13 451	197	PPV 98.6%	True positive 13 648
No (not an antibiotic)	73	2398	NPV 97.0%	True negative 2471
	Sensitivity 99.5%	Specificity 92.4%

Note: CPCSSN = Canadian Primary Care Sentinel Surveillance Network, NPV = negative predictive value, PPV = positive predictive value.