Table 2.

Study objectives

Objectives	Outcome	Population	Instrument(s)
Primary Objective
1. Examine the association between FTS use at baseline and ORRBs during the 28-day observation period	Composite score measuring the number and frequency of eight distinct ORRBs on each day drugs are used during the 28-day observation period (range 0–15)	Full sample1	Weekly surveys 1–4
Secondary Objectives
1. Among FTS users, examine the association between FTS results and ORRBs during the 28-day observation period	Number of ORRBs following each FTS use on each day during the 28-day observation period	FTS sample2	Weekly surveys 1–4
2. Examine the concordance between self-reported substance use and oral fluid results	Oral fluid test positive for fentanyl (yes/no)	Oral fluid sample3	Past 48-hour survey Oral fluid collection
3. Examine the association between FTS use at baseline and the occurrence of a non-fatal overdose during the 28-day observation period	Self-reported non-fatal overdose on each day drugs are used during the 28-day observation period (yes/no)	Full sample1	Weekly surveys 1–4
4. Examine the perspectives and experiences of FTS use among PWUD.	Qualitative: no outcome identified	Qualitative sample4	PWUD interview
5. Examine the perspectives and experiences of organizations distributing FTS, facilitators and barriers to FTS distribution, and cost of FTS strategies	Qualitative: no outcome identified	Organzational partiicipants5	Organizational survey Organizational interview
Exploratory Objectives
1. Characterize patterns of FTS use among PWUD during the 28-day observation period	Using FTS at least once on each day drugs are used during the 28-day observation period (yes/no)	FTS sample2	Weekly surveys 1–4
2. Examine associations between social determinants of health and FTS use during the 28-day observation period	Using FTS at least once on each day drugs are used during the 28-day observation period (yes/no)	FTS sample2	Weekly surveys 1–4
3. Examine associations between social determinants of health and ORRBs during the 28-day observation period	Composite score measuring the number and frequency of eight distinct ORRBs on each day drugs are used during the 28-day observation period (range 0–15)	Full sample1	Weekly surveys 1–4

¹ Full sample is defined by all participants enrolled in the study who completed the baseline survey and at least two of the weekly surveys and reported drug use at least once during the 28-day observation period

² FTS sample is defined by all participants in the Full sample who used FTS at least once during the 28-day observation period

³ Oral fluid sample is defined as all participants who completed the baseline survey, the oral fluid survey and the oral fluid swab, had self-reported use of either non-opioids only (e.g., illicit stimulants or benzodiazepines but not illicit opioids) or any opioid (e.g., illicit opioids only or co-use of illicit opioids with illicit stimulants or benzodiazepines) in the 48 h prior to completing the oral fluid collection, and had valid results for the oral fluid test

⁴ Qualitative sample is defined by all participants in the full sample who completed the qualitative interview

⁵ Organizational participants are defined by all organizations that completed the organizational survey