Table 4.
Power for comparison of HIV incidence between Arms A and B, with 7 communities per arm and Population Cohort of 2,500 adults per community (assuming that on average 2,125 (85%) will be HIV-uninfected at baseline and that loss to follow-up will be 20% after 2 years and 25% after 3 years)
| HIV incidence rate/100 py (control arm) | Between-cluster coefficient of variation (k) | Effectiveness (%) Arm A | Effectiveness (%) Arm B | Power (%) |
|---|---|---|---|---|
| 1.0 |
0.15 |
50% |
20% |
89% |
| 1.0 |
0.15 |
50% |
25% |
78% |
| 1.0 |
0.15 |
55% |
25% |
92% |
| 1.0 |
0.15 |
55% |
30% |
82% |
| 1.0 |
0.15 |
60% |
25% |
98% |
| 1.0 |
0.15 |
60% |
30% |
94% |
| 1.0 |
0.15 |
65% |
25% |
99% |
| 1.0 |
0.15 |
65% |
30% |
99% |
| 1.0 |
0.20 |
50% |
20% |
78% |
| 1.0 |
0.20 |
50% |
25% |
65% |
| 1.0 |
0.20 |
55% |
25% |
83% |
| 1.0 |
0.20 |
55% |
30% |
71% |
| 1.0 |
0.20 |
60% |
25% |
93% |
| 1.0 |
0.20 |
60% |
30% |
87% |
| 1.0 |
0.20 |
65% |
25% |
98% |
| 1.0 |
0.20 |
65% |
30% |
96% |
| 1.5 |
0.15 |
50% |
20% |
94% |
| 1.5 |
0.15 |
50% |
25% |
86% |
| 1.5 |
0.15 |
55% |
25% |
96% |
| 1.5 |
0.15 |
55% |
30% |
90% |
| 1.5 |
0.15 |
60% |
25% |
99% |
| 1.5 |
0.15 |
60% |
30% |
98% |
| 1.0 |
0.20 |
65% |
25% |
99% |
| 1.0 |
0.20 |
65% |
30% |
99% |
| 1.5 |
0.20 |
50% |
20% |
84% |
| 1.5 |
0.20 |
50% |
25% |
72% |
| 1.5 |
0.20 |
55% |
25% |
88% |
| 1.5 |
0.20 |
55% |
30% |
78% |
| 1.5 |
0.20 |
60% |
25% |
96% |
| 1.5 |
0.20 |
60% |
30% |
92% |
| 1.0 |
0.20 |
65% |
25% |
99% |
| 1.0 | 0.20 | 65% | 30% | 98% |