Table 2.
Change in Short Physical Performance Battery and Timed Up-and-Go Measures Since Randomization in the Primary Analysis Population
| 3 Months | 12 Months | 24 Months | p, Interaction* | |||||
|---|---|---|---|---|---|---|---|---|
| Pooled Higher Doses† | 200 IU/day | Pooled Higher Doses† | 200 IU/day | Pooled Higher Doses† | 200 IU/day | Unadj | Adj (significant if <.11) | |
| Total SPPB score (range 0–12)‡ | ||||||||
| No. of participants | 324 | 314 | 253 | 260 | 160 | 171 | ||
| BL, mean ± SD§ | 8.7 ± 2.5 | 8.9 ± 2.3 | 8.7 ± 2.4 | 9.0 ± 2.2 | 8.6 ± 2.4 | 9.0 ± 2.2 | ||
| Change (FU-BL), mean ± SD | −0.1 ± 1.7 | 0.0 ± 1.9 | −0.3 ± 2.0 | −0.2 ± 1.9 | −0.6 ± 2.3 | −0.8 ± 2.5 | ||
| p, change within group‖ | .33 | .88 | .04 | .06 | .001 | <.001 | ||
| p, difference between groups* | .67 | .76 | .76 | .91 | .91 | |||
| Total SPPB balance stand time (s)‡ | ||||||||
| No. of participants | 324 | 313 | 253 | 259 | 160 | 170 | ||
| BL, mean ± SD§ | 26.8 ± 6.0 | 26.9 ± 6.3 | 27.0 ± 5.6 | 27.3 ± 5.9 | 26.9 ± 5.9 | 26.7 ± 6.8 | ||
| Change (FU-BL), mean ± SD | 0.3 ± 5.4 | 0.1 ± 6.3 | −0.5 ± 6.6 | 0.1 ± 6.0 | −2.1 ± 7.4 | −1.3 ± 9.0 | ||
| p, change within group‖ | .25 | .77 | .21 | .84 | .001 | .07 | ||
| p, difference between groups* | .60 | .40 | .35 | .45 | .81 | |||
| SPPB gait speed (m/s)‡ | ||||||||
| No. of participants | 320 | 309 | 244 | 258 | 152 | 162 | ||
| BL, mean ± SD§ | 0.85 ± 0.23 | 0.89 ± 0.23 | 0.86 ± 0.24 | 0.90 ± 0.24 | 0.85 ± 0.24 | 0.93 ± 0.23 | ||
| Change (FU-BL), mean ± SD | −0.01 ± 0.17 | −0.01 ± 0.18 | −0.04 ± 0.17 | −0.04 ± 0.20 | −0.03 ± 0.16 | −0.09 ± 0.21 | ||
| p, change within group‖ | .32 | .58 | .001 | .001 | .007 | <.001 | ||
| p, difference between groups* | .97 | .75 | .04 | .15 | .45 | |||
| SPPB chair stand time (s)‡ | ||||||||
| No. of participants | 275 | 276 | 204 | 219 | 123 | 128 | ||
| BL, mean ± SD§ | 15.3 ± 6.1 | 15.1 ± 4.9 | 15.9 ± 6.8 | 15.1 ± 4.6 | 16.2 ± 7.6 | 14.8 ± 4.2 | ||
| Change (FU-BL), mean ± SD | −0.6 ± 6.3 | −0.2 ± 4.4 | −1.7 ± 7.3 | −0.3 ± 4.6 | −1.7 ± 8.1 | −0.6 ± 3.6 | ||
| p, change within group‖ | .14 | .38 | .001 | .30 | .02 | .05 | ||
| p, difference between groups* | .44 | .02 | .43 | .12 | .45 | |||
| TUG time (s)¶ | ||||||||
| No. of participants | 315 | 305 | 237 | 255 | 149 | 159 | ||
| BL, mean ± SD§ | 11.9 ± 5.9 | 11.0 ± 4.6 | 11.5 ± 4.9 | 10.8 ± 3.5 | 11.5 ± 4.1 | 10.4 ± 3.0 | ||
| Change (FU-BL), mean ± SD | −0.2 ± 2.6 | 0.3 ± 4.0 | 0.3 ± 2.6 | 0.5 ± 2.3 | 1.0 ± 3.0 | 1.1 ± 2.5 | ||
| p, change within group‖ | .11 | .15 | .11 | .001 | <.001 | <.001 | ||
| p, difference between groups* | .009 | .14 | .31 | .07 | .45 |
Note: BL = baseline; FU = follow-up; IU/day = international units per day; SD = standard deviation.
*A longitudinal mixed-effects linear regression model with fixed effects including a single term for treatment, 3 time point terms, and 3 treatment-by-time interaction terms and a random intercept for each participant was fit for each outcome; this model included all available measures of the outcome for all participants, including those with only a baseline measure. Each time-specific p value for difference between dose groups is derived from the corresponding treatment-by-time interaction term. The interaction test for overall difference between groups in differential change from baseline is from a 3-degree-of-freedom test of the combined 3 treatment-by-time interaction terms from the longitudinal model. The Benjamini–Hochberg procedure was used to control the false discovery rate to less than 1/9 (1 out of the maximum number of overall comparisons in each family of analyses comparing dose groups; an adjusted p value is statistically significant if <.11).
†Pooled Higher Doses denotes the combined 1 000, 2 000, and 4 000 IU/day groups.
‡The Short Physical Performance Battery (SPPB) is a 3-part assessment of physical functioning: balance testing, timed 4-m walk, and ability to stand up from a seated position in a chair; each part is scored 0–4, and the total SPPB score (range 0–12) is the sum of the 3 subscores. Higher scores indicate better physical function. The total balance stand time (range 0–30 seconds) combines the stand durations from the 3 balance tests. Gait speed was calculated as 4 m divided by the duration of the walk in seconds. The chair stand test outcome is the time required to complete 5 chair stands, and the test is terminated at 60 seconds if not completed by that time.
§Baseline values are shown for those with a follow-up measure at the given time point.
‖ p Values for time-specific change within group were derived from t-tests.
¶The Timed Up-and-Go (TUG) test is a timed test of standing up from a chair, walking at a normal pace for 3 m, turning, returning to the chair, and sitting down; the test result is the time in seconds to complete all 5 parts. The test is terminated at 60 seconds if not completed by that time.