The Exposure Assessment in Current Time Study: Implementation, Feasibility, and Acceptability of Real-Time Data Collection in a Community Cohort of Illicit Drug Users

Table 2

Feasibility measures by trial*.

Measure	All trials; (𝑁=109)	Trial 1; (𝑁=31)	Trial 2; (𝑁=28)	Trial 3; (𝑁=28)	Trial 4; (𝑁=22)
Total days followup	3047	919	817	757	554
Median days of followup (IQR)	28 (26–29)	29 (28–32)	29 (27–33)	28 (25–28)	27 (26–28)
Daily EMA responses
Random-prompts delivered (N)	11181	3462	2317	2654	2748
Random-prompts delivered (%)	78%	80%	60%	73%	98%
Random-prompts answered (N)	8655	2816	1940	1985	1914
Random-prompts answered (%)	77%	81%	84%	75%	70%
≥80% response	46%	58%	61%	32%	27%
≥60% response	86%	94%	93%	79%	78%
Random-prompts answered (daily mean)	2.84	3.06	2.37	2.62	3.45
Drug using and craving events
Participant-initiated events (N)	2798	656	836	425	881
Median events initiated (IQR)	11 (3–24)	20 (6–26)	12.5 (1–36)	9 (4–20)	6.5 (1–15)
Craving events initiated (IQR)	8 (5–14)	9 (3–17)	5.5 (0–23)	4 (1–10)	4 (1–11)
Using events initiated (IQR)	3 (0–9)	4 (0–12)	1 (0–11)	4 (1–8)	0 (0–3)
Device retention
Device loss (1 per × days)	190.4	306.3	204.3	108.1	277.0
PDAs/smartphones issued	140	38	33	43	26
PDAs/smartphones lost	15	3	4	6	2
GPS issued	61	0	30	31	0
GPS lost	1	0	0	1	0
Participant incentives
Total $ paid	$46,579.00	$12,186.00	$11,986.00	$12,737.00	$9,670.00
Cost/participant	$427.33	$393.10	$428.07	$454.89	$439.55
Cost/person-day	$15.29	$13.26	$14.67	$16.83	$17.45

∗During one-month followup.