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Table. 2 Associations of text message dose and engagement with changes in weight, physical activity and diet

From: Dose and engagement during an extended contact physical activity and dietary behavior change intervention delivered via tailored text messaging: exploring relationships with behavioral outcomes

Text message Characteristic   Body weight(kg) MVPA(min/week) Fruit and vegetables (servings/day)
n Beta(95 % CI) p-value Beta(95 % CI) p-value Beta(95 % CI) p-value
Dose
    Number of texts (all)
High (top 33 %), ≥ 67 38 ref   ref   ref  
Medium, 36–66 38 1.2 (-0.3, 2.7) 0.113 -9 (-62, 44) 0.750 -0.1 (-0.9, 0.6) 0.704
Low (bottom 33 %),<36 38 1.9 (0.3, 3.4) 0.022 -29 (-91, 34) 0.367 0.1 (-0.7, 0.9) 0.801
p-value for trend    0.022   0.368   0.786
  Number of texts (physical activity)
High (top 50 %), ≥ 24 45 ref   ref   ref  
Low (bottom 50 %), 1–23 57 1.6 (0.2, 2.9) 0.022 -11 (-59, 37) 0.642 -0.3 (-1.0, 0.3) 0.339
None 12 0.2 (-2.3, 2.8) 0.848 -25 (-119, 70) 0.604 -0.4 (-1.6, 0.9) 0.551
p-value for trend    0.208   0.534   0.368
  Number of texts (diet)
High (top 50 %), ≥ 24 34 ref   ref   ref  
Low (bottom 50 %), 1–23 55 2.1 (0.6, 3.5) 0.006 -7 (-60, 46) 0.795 -0.6 (-1.3, 0.05) 0.067
None 25 0.5 (-1.3, 2.4) 0.584 67 (1.1, 133) 0.046 0.5 (-0.4, 1.4) 0.262
p-value for trend    0.430   0.055   0.422
  Behavioral prompt texts
Received versus notreceived 59 vs. 55 -1.0 (-2.2, 0.3) 0.131 -2.3 (-53, 48) 0.929 0.1 (-0.5, 0.8) 0.688
Engagement
  Standardised reply rate
High (top 33 %), ≥ 14.6 % 36 ref   ref   ref  
Medium, -1.6–14.6 % 38 0.4 (-1.2, 2.0) 0.591 40 (-13, 93) 0.139 -0.0 (-0.8, 0.7) 0.958
Low (bottom 33 %), <-1.6 % 40 -0.1 (-1.7, 1.5) 0.877 45 (-9, 98) 0.101 0.1 (-0.7, 0.8) 0.842
p-value for trend    0.868   0.104   0.839
  1. Footnote: Table reports regression coefficient and 95 % confidence interval, as assessed via linear regression models, adjusting for baseline values, randomisation strata and confounders. P-value for trend shows p for trend across categories of high medium and low. Abbreviations: n number of participants, MVPA moderate-vigorous physical activity.