YouControl-AFib: a Digital Health Intervention to Promote Physical Activity in Persons with Atrial Fibrillation

Author

Lu Mao

Published

November 7, 2025

1 Statistical analysis

Baseline characteristics were summarized by counts and percentages for categorical variables, and by means (standard deviations; SD) or medians (interquartile ranges; IQR) for continuous variables, as appropriate. Changes in outcome measures from pre- to post-intervention were assessed using paired t-tests. Predictors of clinically meaningful improvement in 6MWD (defined as an increase of \(\geq\) 30 meters) were evaluated using multivariate logistic regression models. P-values < 0.05 were considered statistically significant. All analyses were performed using R (version 4.3.1).

2 Results

2.1 Baseline Characteristics

Baseline characteristics of the n = 51 participants are summarized by gender and overall in Table 1 below.

Table 1: Baseline characteristics by gender
Characteristic F, N = 261 M, N = 251 Overall, N = 511
Age (years) 64 (58, 67) 65 (59, 71) 64 (58, 69)
Body Mass Index (kg/m²) 40.1 (37.2, 43.9) 38.9 (33.6, 42.7) 39.1 (36.5, 43.8)
Number of Ablation Procedures 0.73 (0.78) 0.72 (0.74) 0.73 (0.75)
Number of Cardioversions 0.58 (0.81) 1.32 (1.82) 0.94 (1.43)
Rate Control Medication


    Atenolol 1 (3.8%) 0 (0%) 1 (2.0%)
    Carvedilol 1 (3.8%) 3 (12%) 4 (7.8%)
    Diltiazem 4 (15%) 2 (8.0%) 6 (12%)
    Metoprolol Succinate 11 (42%) 12 (48%) 23 (45%)
    Metoprolol Tartrate 2 (7.7%) 2 (8.0%) 4 (7.8%)
    None 7 (27%) 6 (24%) 13 (25%)
Rhythm Control Medication


    Amiodarone 1 (3.8%) 3 (12%) 4 (7.8%)
    Dofetilide 1 (3.8%) 0 (0%) 1 (2.0%)
    Flecainide 9 (35%) 5 (20%) 14 (27%)
    None 15 (58%) 17 (68%) 32 (63%)
PHQ-9 Score 5.0 (2.0, 7.0) 5.0 (2.0, 7.0) 5.0 (2.0, 7.0)
AFSS Score 6.5 (2.0, 9.8) 5.0 (4.0, 10.0) 6.0 (3.0, 10.0)
AFKAT Score 90.5 (90.5, 95.2) 90.5 (85.7, 95.2) 90.5 (90.5, 95.2)
    Unknown 2 0 2
AFEQT Score 79 (72, 88) 83 (66, 91) 82 (70, 90)
    Unknown 0 1 1
SF-12 Physical Component Score 37.8 (36.3, 41.7) 41.2 (39.9, 44.1) 40.7 (36.8, 43.1)
6-Minute Walk Distance (meters) 389 (361, 451) 464 (420, 522) 430 (369, 491)
LE8 Score 53 (47, 59) 53 (48, 58) 53 (48, 58)
    Unknown 0 1 1
Physical Activity Score 60 (20, 90) 40 (20, 65) 40 (20, 80)
    Unknown 0 1 1
1 Median (IQR); Mean (SD); n (%)

2.2 Outcome Changes

Table 2 summarizes the distribution of outcome measures at pre- and post-intervention timepoints, along with the mean changes, 95% confidence intervals, and p-values from paired t-tests.

Table 2: Changes in outcome measures from pre- to post-intervention
Measure N Pre-Mean (SD) Post-Mean (SD) Mean Change (95% CI) P-value
6-Minute Walk Distance (m) 48 423.7 (97.3) 452.9 (100.7) 29.2 (12.8, 45.5) <0.001
PHQ-9 Score 46 4.8 (3.3) 3.9 (3.5) -1.1 (-1.9, -0.3) 0.011
AFSS Score 46 6.9 (5.5) 6.1 (5.5) -0.9 (-2.2, 0.5) 0.208
AFKAT Score 46 91.3 (5.9) 92.0 (5.5) 0.7 (-0.9, 2.4) 0.374
AFEQT Score 35 78.6 (15.4) 82.9 (15.5) 5.2 (0.7, 9.6) 0.023
SF-12 Physical Component Score 43 40.4 (4.3) 41.6 (5.0) 1.2 (0.0, 2.4) 0.048
SF-12 Mental Component Score 43 48.0 (5.5) 47.7 (4.9) -0.3 (-2.3, 1.6) 0.725

Figure 1 and Figure 2 show the distributions of 6MWD and survey response measures, respectively, at pre- and post-intervention timepoints using boxplots, with individual participant changes connected by lines.

Figure 1: Boxplot of 6-Minute Walk Distance (6MWD) at pre- and post-interventions
Figure 2: Boxplots of survey scores at pre- and post-interventions

2.3 \(\Delta\) 6MWD \(\geq 30\) m

Table 3 summarizes the counts of participants by \(\Delta\) 6MWD (decreased: \(\leq 0\), mild improvement: \((0, 30)\), clinically meaningful improvement).

Table 3: 6MWD improvement categories and counts
Characteristic N = 511
Δ6MWD
    Decreased (≤0m) 14 (29%)
    Mild Improvement (0-30m) 10 (21%)
    Meaningful Improvement (≥30m) 24 (50%)
    Unknown 3
1 n (%)

Table 4 summarizes baseline characteristics potentially associated with clinically meaningful 6MWD improvement (\(\Delta\) 6MWD \(\geq\) 30m).

Table 4: Baseline characteristics potentially associated with clinically meaningful 6MWD improvement (>=30m)
Characteristic Δ6MWD<30m, N = 241 Δ6MWD≥30m, N = 241 p-value2
Age (years) 64 (56, 68) 64 (59, 70) 0.9
Gender

>0.9
    F 12 (50%) 12 (50%)
    M 12 (50%) 12 (50%)
Urban Residence 14 (58%) 7 (29%) 0.042
Number of Ablation Procedures 1.00 (0.00, 1.00) 0.50 (0.00, 1.00) 0.4
Number of Cardioversions 1.00 (0.00, 1.00) 0.00 (0.00, 1.00) 0.3
Rate Control Medication

0.8
    Atenolol 0 (0%) 1 (4.2%)
    Carvedilol 2 (8.3%) 2 (8.3%)
    Diltiazem 3 (13%) 3 (13%)
    Metoprolol Succinate 13 (54%) 10 (42%)
    Metoprolol Tartrate 2 (8.3%) 1 (4.2%)
    None 4 (17%) 7 (29%)
Rhythm Control Medication

0.15
    Amiodarone 4 (17%) 0 (0%)
    Dofetilide 1 (4.2%) 0 (0%)
    Flecainide 6 (25%) 7 (29%)
    None 13 (54%) 17 (71%)
Body Mass Index (kg/m²) 40.1 (36.9, 45.6) 38.9 (36.1, 42.8) 0.3
LE8 Score 50 (43, 54) 55 (50, 61) 0.035
    Unknown 0 1
Physical Activity Score 40 (20, 60) 80 (30, 90) 0.067
    Unknown 0 1
1 Median (IQR); n (%)
2 Wilcoxon rank sum test; Pearson’s Chi-squared test; Fisher’s exact test; Wilcoxon rank sum exact test
  • Non-urban residence and higher LE8 score at baseline were significantly associated with \(\Delta\) 6MWD \(\geq\) 30m.

A multivariate logistic regression model for \(\Delta\) 6MWD \(\geq\) 30m is used to assess the independent effects of urban residence and LE8 score at baseline. The results As shown in Table 5 below, both are border-line significant.

Table 5: Multivariate logistic regression model for clinically meaningful 6MWD improvement (>=30m)
Characteristic OR1 95% CI1 p-value
Urban Residence


    No — —
    Yes 0.31 0.08, 1.07 0.071
LE8 Score (per unit increase) 1.08 1.01, 1.19 0.054
1 OR = Odds Ratio, CI = Confidence Interval
  • Urban residence reduces the odds of achieving \(\Delta\) 6MWD \(\geq\) 30m by 1-0.31=69%;
  • Each unit increase in LE8 score at baseline increases the odds of achieving \(\Delta\) 6MWD \(\geq\) 30m by 1.08-1=8%.

2.4 Living Well with AFib Clinic

Similar analyses of 6MWD changes are performed for the Living Well with AFib Clinic cohort and shown in Table 6, Figure 3, and Table 7 below.

Table 6: Changes in 6-Minute Walk Distance (6MWD) from pre- to post-intervention for Living Well with AFib Clinic
Measure N Pre-Mean (SD) Post-Mean (SD) Mean Change (95% CI) P-value
6-Minute Walk Distance (m) 28 382.9 (102.1) 402.0 (119.2) 19.1 (0.2, 38.0) 0.048
Figure 3: Boxplot of 6-Minute Walk Distance (6MWD) at pre- and post-interventions for Living Well with AFib Clinic
Table 7: 6MWD improvement categories and counts for Living Well with AFib Clinic
Characteristic N = 281
Δ6MWD
    Decreased (≤0m) 9 (32%)
    Mild Improvement (0-30m) 7 (25%)
    Meaningful Improvement (≥30m) 12 (43%)
1 n (%)