Table 1.

Summary of study phases to classify emergency medical services trip reports for potential opioid misuse, Denver, Colorado, 2017.

Phase	Purpose	Description of methods	Time frame
1	Assess performance of keyword search approaches	Searched trip reports for keywords (ie, “naloxone,” “heroin,” and both combined) and reviewed charts of identified reports to assess positive predictive value	August 2017 to April 2018
2	Train and test supervised machine learning classification	Guided machine learning models using previous phase’s chart review classification results and selected the highest performing algorithm in binary classification of opioid misuse and heroin use	August 2017 to April 2018
3	Validate performance measures across approaches	Compared the highest performing machine learning algorithm with the performance of searches of keywords “naloxone,” “heroin,” and combination of both	September 2018