Table 3. Exploratory Outcomes by Intervention Group at 6 Months.
| Measure | Adjusted mean change (95% CI)a | Difference in adjusted mean changes (95% CI)a | P value | |
|---|---|---|---|---|
| Attention control | I-STAND intervention | |||
| Standing time, min/d | ||||
| 3 mo | 4.46 (−5.00 to 13.91) | 31.58 (19.97 to 43.20) | 27.13 (12.00 to 42.26) | <.001 |
| 6 mob | 4.81 (−8.67 to 18.29) | 32.48 (19.64 to 45.33) | 27.67 (9.30 to 46.04) | .003 |
| Stepping time, min/d | ||||
| 3 mo | 2.46 (−0.88 to 5.80) | 6.81 (3.26 to 10.36) | 4.35 (−0.60 to 9.30) | .09 |
| 6 mob | 3.77 (−0.40 to 7.94) | 7.81 (4.12 to 11.50) | 4.04 (−1.59 to 9.67) | .16 |
| Mean daily step count | ||||
| 3 mo | 212.07 (−126.05 to 550.19) | 568.15 (249.63 to 886.68) | 356.08 (−110.38 to 822.54) | .14 |
| 6 mob | 352.42 (−36.62 to 741.46) | 510.14 (175.52 to 844.75) | 157.72 (−356.73 to 672.16) | .55 |
| Mean sitting bout duration, min/d | ||||
| 3 mo | −0.43 (−1.25 to 0.39) | −1.35 (−2.37 to −0.33) | −0.92 (−2.33 to 0.49) | .20 |
| 6 mob | −0.04 (−0.95 to 0.87) | −1.85 (−2.73 to −0.98) | −1.81 (−3.11 to −0.52) | .006 |
| Prolonged sitting bouts, No. | ||||
| 3 mo | −0.18 (−0.40 to 0.04) | −0.72 (−0.98 to −0.45) | −0.54 (−0.89 to −0.18) | .003 |
| 6 mob | −0.13 (−0.40 to 0.14) | −0.70 (−0.98 to −0.42) | −0.57 (−0.96 to −0.18) | .004 |
| Chair stands, s | ||||
| 3 mo | −0.53 (−1.41 to 0.35) | −1.29 (−2.09 to −0.49) | −0.76 (−1.95 to 0.43) | .21 |
| 6 mob | −1.20 (−2.06 to −0.34) | −1.15 (−2.14 to −0.16) | 0.05 (−1.29 to 1.39) | .95 |
For adjusted mean change and difference, we fit a linear regression model with generalized estimating equations on the outcome change from baseline, including 3- and 6-month time points in the same model with indicators for the 6-month time point, I-STAND intervention, and interactions among these indicators, adjusting for baseline outcome, post–COVID-19 randomization indicator, baseline outcome and post–COVID-19 interaction, county, age, gender, race, body mass index, arthritis, physical function, diabetes, hypertension, retirement status, and number of hypertensive medication classes. To obtain the adjusted mean change, we assumed the mean baseline covariate response for all randomized participants.
Six months is the primary time point of the trial.