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. 2025 Apr 22;27:e69425. doi: 10.2196/69425

Table 1.

Participant characteristics at baseline.

Participant characteristics Total (n=756) Intervention (n=377) Control (n=379)
Age (years), median (IQR) 17 (16-18) 17 (16-18) 17 (16-18)
Sex, n (%)

Female 520 (69) 265 (70) 255 (67)

Male 236 (31) 112 (30) 124 (33)
Economy, n (%)

Very good 246 (33) 112 (30) 134 (35)

Average 447 (59) 232 (62) 215 (57)

Not so good 56 (7) 30 (8) 26 (7)

Not good at all 7 (1) 3 (1) 4 (1)
Parents educationa, n (%)

Primary 52 (7) 25 (7) 27 (7)

Secondary 261 (35) 131 (35) 130 (34)

Tertiary 443 (59) 221 (59) 222 (59)
Region of birthb, n (%)

Sweden 648 (86) 324 (86) 324 (85)

Other 108 (14) 53 (14) 55 (15)
Parents’ region of birthb, n (%)

Sweden 546 (72) 268 (71) 278 (73)

Other 210 (28) 109 (29) 101 (27)
Satisfaction with lifec, median (IQR) 7 (6-8) 7 (6-8) 7 (6-8)
Psychosocial variablesd, median (IQR)

Importance 7 (5-9) 7 (5-9) 7 (5-9)

Confidence 6 (5-8) 6 (5-8) 6 (5-8)

Know-how 6 (5-8) 6 (5-8) 6 (4-8)
Primary outcomes

Number of weekly standard drinks (12 g pure alcohol) consumede, median (IQR) 12.5 (10-15.8) 12.5 (10.3-15) 13 (10-17.8)

Monthly frequency of heavy episodic drinking (ie, ≥ 4 standard drinks)e, median (IQR) 2 (1-3) 2 (1-3) 2 (1-3)

Number of daily portions (100 g) of fruit and vegetables consumede, median (IQR) 1 (0.7-1.8) 1 (0.7-2) 1 (0.7-2)

Number of weekly sugary drinks (33 cl) consumede, median (IQR) 5 (2-7) 2 (2-5) 5 (2-7)

Weekly time spent in MVPAf (minutes)e, median (IQR) 135 (60-240) 165 (60-240) 135 (45-240)

Smoking any cigarette in the past weeke, n (%) 140 (19) 68 (18) 72 (19)
Secondary outcomes, median (IQR)

Number of weekly portions of candy or snacks 2 (2-5) 2 (2-5) 2 (2-5)

BMI (kg/m2)g 21.9 (19.7-24.6) 21.9 (19.7-24.4) 21.9 (19.8-24.8)

Number of cigarettes smoked weekly among smokers 7 (2-34.3) 5.5 (1.8-30.5) 9.5 (2-35.3)

aAssessed as “Please select the highest education for your mother and father.”

bAssessed as “Where were you/your parents born?”

cCantril’s ladder [64] “Thinking about your own life and personal circumstances, how satisfied are you with your life as a whole?” responded on a 11-point Likert scale where 0 represent not at all satisfied.

dDefined as follows: Importance: “How important do you think it is to improve your lifestyle or sustain your healthy behaviors?”; Confidence: “How confident are you that you will be able to change your lifestyle or sustain your healthy behaviors?”; Know-how: “How well do you know how to change your lifestyle?”; all items responded on a 10-point Likert scale.

eAmong participants at-risk for the behavior at baseline (weekly alcohol consumption, n=46, heavy episodic drinking, n=338, fruit and vegetables, n=738, sugary drinks, n=469, moderate to vigorous physical activity n=527, and cigarette smoking, n=140).

fMVPA: moderate to vigorous physical activity.

gCalculated by asking participants at baseline about their height (in cm, numerical measure) and weight (in kg, numerical measure) to determine their BMI.