Table A2.3

 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*DifferenceNo of index patients in each study arm
80% Power90% Power95% 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%376496609
40%20%−20%91119144
50%40%−10%408538661
50%30%−20%103134163
60%50%−10%408538538
60%40%−20%107140170