Table 2.
Description of study, sample, and intervention characteristics of 20 included studies.
| Characteristic | Variable | Summary Statistic | |||
| Study | |||||
|
|
Publication year, median (range) | 2013 (2005-2015) | |||
|
|
Data collection year, median (range) | 2009 (2004-2013) | |||
| Sample | |||||
|
|
Demographics | ||||
|
|
Sample size, initial/final | 15,593/12,477 | |||
|
|
Women, mean % (SDa) | 54 (20) | |||
|
|
Age, mean (SD) | 29 (8) | |||
|
|
Race, mean % White (SD), kb=9 | 69 (29) | |||
|
|
Region of sample, k (%) | ||||
|
|
Europe | 9 (45) | |||
|
|
North America | 6 (30) | |||
|
|
Oceania | 3 (15) | |||
|
|
Asia | 2 (10) | |||
| Methods | |||||
|
|
Recruitment method, k | ||||
|
|
Web-based | 6 (30%) | |||
|
|
Offline | 8 (40%) | |||
|
|
Web-based and offline | 6 (30%) | |||
|
|
Enrollment Procedures, k (%) | ||||
|
|
Electronic | 6 (30%) | |||
|
|
Phone | 1 (5%) | |||
|
|
In-person | 5 (25%) | |||
|
|
Multiple | 8 (40%) | |||
|
|
Study design, k (%) | ||||
|
|
Random assignment of groups | 2 (10) | |||
|
|
Matching then random assignment | 8 (40) | |||
|
|
True randomization | 10 (50) | |||
|
|
Treatment standardized | 20 (100) | |||
|
|
Pre- and post-test, k (%) | ||||
|
|
Pretest post-test design | 20 (100) | |||
|
|
Follow-up rate, k (%) | ||||
|
|
85%-100% completed | 9 (45) | |||
|
|
70%-84% completed | 6 (30) | |||
|
|
<70% completed | 5 (25) | |||
|
|
Follow-up length, k (%) | ||||
|
|
6 months or longer | 3 (15) | |||
|
|
3-5 months | 3 (15) | |||
|
|
Less than 3 months | 14 (70) | |||
|
|
Retention, k (%) | ||||
|
|
Withdrawal/drop-outs reported | 20 (100) | |||
|
|
Attrition, cases lost to follow-up considered | 20 (100) | |||
|
|
Data collection, k (%) | ||||
|
|
Anonymous | 1 (5) | |||
|
|
Collateral verification | 1 (5) | |||
|
|
Used objective measures (≥50% cases) | 7 (35) | |||
|
|
Independent/double-blinding | 11 (55) | |||
|
|
Data treatment, k (%) | ||||
|
|
Intent-to-treat, reported and used | 20 (100) | |||
|
|
Data analyses, k (%) | ||||
|
|
Appropriate for the study design | 2 (10) | |||
|
|
Controlled for baseline/other covariates | 18 (90) | |||
|
|
Single versus multiple site study design, k (%) | ||||
|
|
Multisite, replication at ≥2 sites | 0 (0) | |||
| Intervention | |||||
|
|
Theory used to guide research, k (%) | 19 (86) | |||
|
|
Intervention duration (days), median (range) | 87 (5-378) | |||
|
|
Intervention delivery, k (%) | ||||
|
|
Text messages | 11 (50) | |||
|
|
Text messages + other delivery format | 11 (50) | |||
|
|
Text messages sent, median (range) | 140 (14-280) | |||
|
|
Frequency of text messages, kc | ||||
|
|
Low (<1/week), fixed-dose | 1 | |||
|
|
High (>1/week), fixed-dose | 4 | |||
|
|
Decreasing | 6 | |||
|
|
Varied | 13 | |||
|
|
User selected | 3 | |||
|
|
Communication flow, k (%) |
|
|||
|
|
One-way texts | 2 (9) | |||
|
|
Two-way texts | 20 (91) | |||
|
|
Other Intervention Content (k=11) | ||||
|
|
N sessions, median (range) | 2 (1-232) | |||
|
|
Other Intervention Delivery, kc | ||||
|
|
In-person | 2 | |||
|
|
Facilitated by computer/technology | 1 | |||
|
|
Computer/technology | 6 | |||
|
|
Print materials | 2 | |||
|
|
Phone | 4 | |||
|
|
Tailored and Targeted Intervention | ||||
|
|
Intervention content tailored | 21 (95) | |||
|
|
Intervention content targeted | 16 (73) | |||
|
|
Other Intervention Content, k (%) | ||||
|
|
Decisional balance exercise | 12 (55) | |||
|
|
Personalized feedback | 16 (73) | |||
|
|
Self-efficacy | 20 (91) | |||
|
|
Self-management skills | 22 (100) | |||
|
|
Goal-setting/harm prevention plans | 19 (86) | |||
|
|
Counseling provided, k (%)c | ||||
|
|
In-person | 1 (5) | |||
|
|
Phone/voice | 3 (14) | |||
|
|
Computer | 3 (14) | |||
|
|
Social support, k (%) | ||||
|
|
Any | 12 (55) | |||
|
|
Individual | 11 | |||
|
|
Group | 1 | |||
|
|
Biomedical intervention, k (%) | ||||
|
|
Any | 9 (41) | |||
|
|
Recommended | 7 | |||
|
|
Provided | 2 | |||
|
|
Treatment fidelity, k (%) | ||||
|
|
15 (68) | ||||
| Controls | |||||
|
|
Type of control, k (%) | ||||
|
|
WL/NT/AOd | 2 (10) | |||
|
|
Irrelevant content, time-matched | 2 (10) | |||
|
|
Irrelevant content, not time-matched | 4 (20) | |||
|
|
Relevant content, time-matched | 2 (10) | |||
|
|
Relevant content, not time-matched | 10 (50) | |||
|
|
Control delivery, k (%) | ||||
|
|
Text messages | 6 (33) | |||
|
|
Text messages + other delivery format | 4 (22) | |||
|
|
Other delivery format | 8 (44) | |||
aStandard deviation.
bNumber of studies.
cMultiple categories were possible.
dWait-list/no treatment/assessment only control.