Table 1.
Univariate Relationships Between Sensor and Survey Variables and Fatigue
| Variable | M (SD) | ICC | r With Fatigue |
|---|---|---|---|
| Fitbit activity data | |||
| Total steps per day | 8,800 (6,623) | .70 | −.20*** |
| Active minutes per day | 53.0 (78.2) | .78 | −.31*** |
| Fitbit sleep data | |||
| Time in bed (min) | 437.6 (158.8) | .87 | +.14** |
| Total sleep time (min) | 385.1 (140.3) | .87 | +.16** |
| Sleep efficiency (% time in bed asleep) | 0.87 (0.05) | .88 | +.14** |
| Wake after sleep onset (no. of times) | 6.91 (3.87) | .92 | +.03 n.s. |
| Awake after sleep onset (% of nights) | 32.0% (46.6%) | .89 | +.02 n.s. |
| % of time awake after going to sleep | 11.8% (4.2%) | .99 | −.16** |
| % of sleep time spent in light sleep | 60.1% (11.1%) | .83 | +.33*** |
| % of sleep time spent in deep sleep | 15.0% (6.1%) | .80 | +.21*** |
| % of sleep time spent in REM sleep | 18.3% (7.5%) | .89 | +.16* |
| Fitbit heart rate data | |||
| Average daily heart rate (beats/min) | 81.3 (11.2) | .60 | +.06 n.s. |
| Maximum daily heart rate (beats/min) | 126.8 (19.7) | .87 | −.34** |
| Minimum daily heart rate (beats/min) | 57.6 (8.1) | .70 | +.10* |
| Resting daily heart rate (beats/min) | 68.6 (8.4) | .29 | +.18*** |
| HRV (SD of ms/beat) | 117.2 (37.4) | .73 | −.28*** |
| Daily survey measures (on a 1–4 scale) | |||
| Self-efficacy (general) | 3.41 (0.51) | .77 | −.71*** |
| Mood | 3.09 (0.75) | .67 | −.33*** |
| Stress | 2.10 (0.66) | .44 | +.51*** |
| Coping | 2.55 (0.68) | .63 | +.13*** |
| Approach coping | 2.54 (0.73) | .98 | +.06 n.s. |
| Avoidance coping | 2.56 (0.76) | .94 | +.24*** |
| Perceived social support | 3.12 (0.83) | .66 | −.11** |
| Perceived stigma | 2.03 (0.77) | .46 | +.01 n.s. |
| Motivation to take ART medication | 3.78 (0.33) | .65 | +.05 n.s. |
| Barriers to self-management (overall) | 1.33 (0.42) | .44 | +.34*** |
| Substance use | 1.31 (0.78) | .01 | +.30*** |
| ART side effects | 1.67 (0.95) | .94 | +.21*** |
| Travel | 1.13 (0.42) | .01 | +.26*** |
| Irritated at having to manage HIV | 1.38 (0.79) | .99 | +.29*** |
| Confusion | 1.19 (0.56) | .01 | +.20*** |
| ART medication adherence (% of days) | 97% (16%) | .92 | −.05 n.s. |
Note. Lower ICCs demonstrated more variability within a single person over time, while higher ICCs indicated that results from the same person on different days were more consistent. ART = antiretroviral treatment; HRV = heart rate variability; ICC = intraclass correlation; n.s. = not significant; REM = rapid eye movement.
*
p< .05
**
p< .01
***
p< .001.