Booster Training Case Study

Of 5000 individuals contacted for participation, 2802 were randomized in agreement with the analytical and scientific sample. Of those not randomized, about 41% were unfortunately ineligible, also 57% unfortunately refused, and 1% were improperly randomized.
To evaluate the effects of ACTIVE training, an intention-to-treat analysis was conducted using a repeated-measures mixed-effects model for each cognitive and daily function composite outcome. In these models included several design features and three interaction terms to measure the net effect of training and both the net effect and added effect of booster training. Time was treated as a categorical variable (baseline, 1, 2, 3, 5, 10 years). The following baseline measures also were included: age, sex, cognitive status (MMSE score), years of education, and visual acuity.
89% of participants completed the training intervention. Completers were younger, had more education, and had higher baseline MMSE and brain/cognitive function scores.
Training effects were assessed by comparing mean improvement from baseline to year 10 in each of the three training groups to mean improvement from baseline to year 10 in the non-trained control group. Effects of booster training were assessed similarly by comparing mean improvement from baseline to year 10 in subjects receiving booster training to mean improvement from baseline to year 10 in subjects who did not receive booster training. This comparison was made for each of the three cognitive interventions. The analyses were first performed using available data. Then we assessed the impact of missing data by repeating the analysis with multiple imputation and by conducting a sensitivity analysis that forced missing cognitive and daily function scores to be low. All statistical tests were two-sided. Analyses were conducted at the data coordinating