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. 2021 Oct 26;8(10):e29397. doi: 10.2196/29397

Table 3.

Unadjusted association between baseline characteristics and Web Booster engagement.

Predictors Web Boosters

0 (n=95) 1 or 2 (n=43) 3 (n=108) Test statistic (df) P value Effect sizea
Follow-up completion, n (%)

4 months 31 (17.61) 37 (21.02) 108 (61.36) χ22=118.0 <.001 .69

8 months 35 (20.00) 34 (19.43) 106 (60.57) χ22=94.1 <.001 .62

12 months 37 (21.14) 36 (20.57) 102 (58.29) χ22=79.8 <.001 .57
Baseline characteristics

Sex (male), n (%) 86 (41.55) 34 (16.07) 87 (42.03) χ22=4.7 .09 .14

Age, mean (SD) 27.4 (7.5) 27.9 (7.4) 30.5 (7.7) F1,244=8.54 .004 .03

Race, n (%) χ22=1.1 .57 .07


White 77 (40.10) 34 (17.71) 81 (42.19)




Other 18 (33.33) 9 (16.67) 27 (50.00)



Hispanic (yes), n (%) 13 (48.15) 3 (11.11) 11 (40.74) χ22=1.4 .48 .08
Marital status, n (%) χ26=2.4 .87 .07

Married 25 (33.33) 13 (17.33) 37 (49.33)



Living together 16 (38.10) 7 (16.67) 19 (45.24)



Widowed, divorced, or separated 10 (35.71) 5 (17.86) 13 (46.43)



Never married 44 (43.56) 18 (17.82) 39 (38.61)


Highest grade completed, n (%) χ24=26.1 <.001 .23

High school or less 30 (58.82) 9 (17.65) 12 (23.53)



Some college 54 (40.60) 25 (18.80) 54 (40.60)



College or more 11 (17.74) 9 (14.52) 42 (67.74)


Rank, n (%) χ24=19.1 <.001 .20

E1-E4 60 (45.11) 29 (21.80) 44 (33.08)



E5-E9 31 (32.98) 14 (14.89) 49 (52.13)



WO1-WO5/O1-O9 4 (21.05) 0 (0) 15 (78.95)


Employed (yes), n (%) 81 (36.99) 40 (18.26) 98 (44.75) χ22=2.4 .22 .10
Household income (US $), n (%) χ26=19.1 .004 .20

25,000 or less 29 (46.48) 10 (15.38) 26 (40.00)



25,000-50,000 33 (24.49) 12 (16.90) 26 (36.62)



50,000 or more 24 (24.49) 19 (19.39) 55 (56.12)



Refused 9 (75.00) 2 (16.67) 1 (8.33)


Ever deployed (yes), n (%) 45 (37.19) 23 (19.01) 53 (43.80) χ22=0.4 .80 .04
Trauma exposure (yes), n (%) 21(26.25) 17 (21.25) 42 (52.50) χ22=7.6 .02 .18
Illicit drug use (yes), n (%) 7 (26.92) 8 (30.77) 11 (42.31) χ22=3.9 .14 .13
Cannabis use (yes), n (%) 14 (50.00) 5 (17.86) 9 (32.14) χ22=2.0 .36 .09
AUDITb, mean (SD) 9.4 (5.4) 9.3 (5.8) 9.6 (5.8) F1,244=0.08 .77 <.01
PHQc, mean (SD) 5.1(6.0) 6.0 (5.4) 5.1 (5.8) F1,244=0.00 .99 <.01
GADd, mean (SD) 5.7 (5.5) 6.7 (5.3) 5.1 (5.3) F1,244=0.71 .40 <.01
Drink and drive, mean (SD) 0.3 (0.7) 0.3 (0.8) 0.3 (0.7) F1,244=0.09 .77 <.01
Readiness to change, n (%) 4.1 (3.0) 3.9 (2.9) 3.9 (2.9) F1,244=0.23 .63 <.01
Confidence reduction, n (%) 5.1 (3.0) 4.5 (2.9) 4.4 (3.3) F1,244=2.19 .13 .01
SIPe-Impulse control, n (%) 1.0 (1.5) 1.2 (1.6) 1.1(1.6) F1,244=0.24 .63 <.01
Motives to drink, mean (SD)

Social 4.6 (2.3) 5.4 (2.3) 5.1 (2.4) F1,244=2.01 .16 .01

Coping with anxiety 3.7 (2.1) 4.0 (2.1) 3.9 (2.3) F1,244=0.36 .55 <.01

Coping with depression 4.8 (2.8) 5.3 (2.1) 5.3 (3.0) F1,244=1.32 .25 .01

Enhancement 4.1 (2.3) 4.5 (2.0) 4.1 (2.0) F1,244=0.00 .96 <.01

Conformity 2.6 (1.6) 2.6 (1.6) 2.7 (1.5) F1,244=0.21 .65 <.01

Physical 4.4 (2.3) 4.6 (1.9) 4.5 (2.1) F1,244=0.15 .70 <.01

aEffect size reported as Cramer V for chi-square tests and as R-square for F tests.

bAUDIT: Alcohol Use Disorders Identification Test.

cPHQ: Patient Health Questionnaire.

dGAD: General Anxiety Disorder Questionnaire.

eSIP: Short Index of Problems.