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. Author manuscript; available in PMC: 2024 Jul 1.
Published in final edited form as: J Am Geriatr Soc. 2023 Feb 23;71(7):2208–2218. doi: 10.1111/jgs.18290

Table 3.

Linear mixed models of physical activity over time comparing the pooled higher doses group (≥1000 IU/d) versus the control group (200 IU/d).

Model 1 (n=571) Model 2 (n=566) Model 3 (n=565)
Variable B SE p value B SE p value B SE p value
TAC
 Baseline TAC 0.859 0.019 <0.001 0.839 0.021 <0.001 0.826 0.021 <0.001
 Timea −24979 15705 0.113 −23612 15729 0.134 −23810 15727 0.131
 Dose group 6476 29607 0.827 5962 29695 0.841 7817 29686 0.793
 Dose group*timea −10099 19750 0.610 −11332 19811 0.568 −10886 19838 0.584
 Serum vitamin Db 7004 37293 0.851 −1407 37584 0.970 −2507 37506 0.947
 Time*serum vitamin D −41911 21109 0.048 −40534 21166 0.057 −40302 21179 0.058
 Dose group*serum vitamin D 12713 48377 0.793 20458 48591 0.674 21146 48433 0.663
ASTP (%)
 Baseline ASTP 0.842 0.021 <0.001 0.817 0.022 <0.001 0.808 0.022 <0.001
 Timea 0.307 0.231 0.185 0.290 0.231 0.209 0.287 0.230 0.213
 Dose group 0.093 0.378 0.807 0.063 0.379 0.869 0.037 0.381 0.922
 Dose group*timea −0.043 0.290 0.882 −0.055 0.290 0.851 −0.073 0.291 0.803
 Serum vitamin D −0.023 0.477 0.962 0.057 0.480 0.905 0.066 0.481 0.892
 Time*serum vitamin D 0.607 0.310 0.051 0.627 0.310 0.045 0.636 0.310 0.042
 Dose group*serum vitamin D −0.486 0.624 0.437 −0.567 0.624 0.364 −0.573 0.624 0.360
Active time (min/day)
 Baseline active time 0.844 0.021 <0.001 0.828 0.022 <0.001 0.820 0.022 <0.001
 Timea −4.93 3.44 0.153 −4.66 3.45 0.177 −4.76 3.44 0.168
 Dose group −0.643 6.15 0.917 −0.525 6.19 0.933 0.021 6.19 0.997
 Dose group*timea 1.42 4.33 0.742 1.21 4.34 0.782 1.08 4.34 0.805
 Serum vitamin D 0.443 7.71 0.954 −0.636 7.80 0.935 −0.940 7.79 0.904
 Time*serum vitamin D −11.80 4.63 0.011 −11.57 4.64 0.013 −11.41 4.64 0.015
 Dose group*serum vitamin D 7.83 9.85 0.428 8.63 9.93 0.386 8.75 9.92 0.379

Note. N=571. TAC = total activity counts, ASTP = Activity fragmentation defined by the active-to-sedentary transition probability

a

Time=0 at baseline, 0.25 at 3 months follow-up visit, 1 at 12 months follow-up visit, and 2 at 24 months follow-up visit.

Linear mixed effects model with random intercept and slope, using unstructured correlation structure. Model 1 was the unadjusted model; Model 2 was adjusted for age, sex, and race (non-white vs. white); Model 3 was additionally adjusted for BMI, number of comorbidities, and history of falls (fell vs. did not fall).

b

Baseline serum vitamin D at 10–19 ng/mL (deficient) vs. 20–29 ng/mL (low).