Table 4.
Total number of participants enrolled in trial (assigned in equal numbers to the physical activity and successful aging interventions) required to provide 80% and 90% power to detect intervention effects of 20%, 25%, and 30% over 4 years of follow-up.*
| Outcome | 80% Power
|
90% Power
|
||||
|---|---|---|---|---|---|---|
| Intervention Effect
|
Intervention Effect
|
|||||
| 20% | 25% | 30% | 20% | 25% | 30% | |
| 400 meter walk | ||||||
| Time until first failure | 1669 | 1056 | 719 | 2234 | 1414 | 962 |
| Two successive failures | 3453 | 2120 | 1403 | 4624 | 2839 | 1678 |
|
| ||||||
| 4 meter walk | ||||||
| Time until first failure | 5178 | 3134 | 2085 | 6934 | 4196 | 2792 |
| Two successive failures | 16881 | 9650 | 6597 | 22603 | 12921 | 8833 |
|
| ||||||
| SPPB | ||||||
| Mean difference over follow-up | 4673 | 2991 | 2077 | 6257 | 4105 | 2781 |
|
| ||||||
| SRDS | ||||||
| Mean difference over follow-up | 14010 | 8967 | 6233 | 18760 | 12006 | 8338 |
*
Projections are based on simulations incorporating means and transition rates from Tables 2 and 3 for the successful aging group. As an examples, for a 20% intervention effect the 400 meter transition rates for the intervention group were calculated as 6.9% × 0.8 = 5.5%, 7.9% × 0.8 = 6.3%, and 33.3% × 1.2 = 40.0% and the mean changes in the SPPB for the intervention group were calculated as 0.589 × 1.2 = 0.707 and −0.168 × 0.8 = −0.134.