Number of patients in each study arm required according to desired odds ratio and study power
| Success rate in GU clinic* | Success rate in GP surgeries* | Difference | No of index patients in each study arm | ||
|---|---|---|---|---|---|
| 80% Power | 90% Power | 95% Power | |||
| *Proportion of index patients with one or more partners who received treatment, defined as return of a study contact slip, matching of name on clinic computer or report by index case at telephone follow up. Based on a continuity corrected χ2 test with a 0.05 two sided significance level. | |||||
| 40% | 30% | −10% | 376 | 496 | 609 |
| 40% | 20% | −20% | 91 | 119 | 144 |
| 50% | 40% | −10% | 408 | 538 | 661 |
| 50% | 30% | −20% | 103 | 134 | 163 |
| 60% | 50% | −10% | 408 | 538 | 538 |
| 60% | 40% | −20% | 107 | 140 | 170 |