Table 2.

Performance of natural language processing approaches to identify potential opioid misuse and heroin use in unseen September 2018 paramedic trip reports, Denver, Colorado.

Approach	Number of identified trip reports by approach (N)	Positive predictive value, n (%)	Correlationa between weekly opioid misuse counts and chart review assessment
Naloxone search among administered medications	63	43 (68.3)	0.86
Heroin search in narratives	129	128 (99.2)	0.99
Combined search approach (naloxone or heroin)	171	151 (88.3)	1
Machine learningb on combined search approach	146	144 (98.6)	0.99

^aPearson correlation coefficient.

^bL1-regularized logistic regression.