Table 1 Impact of sensitivity and specificity on the treatment effect estimate in a randomised trial. Hypothetical example based on the WOMAN-2 trial of 10,000 women (5000 per arm), assuming a true placebo group event rate of 6% and a true relative risk of 0.75
From: Postpartum haemorrhage in anaemic women: assessing outcome measures for clinical trials
Varying specificity, 100% sensitivity | Varying sensitivity, 100% specificity | ||||||
|---|---|---|---|---|---|---|---|
Specificity | Outcome events (n) | RR (95% CI) | Sensitivity | Outcome events (n) | RR (95% CI) | ||
TXA | Placebo | TXA | Placebo | ||||
100% | 225 | 300 | 0.75 (0.62−0.88) | 100% | 225 | 300 | 0.75 (0.62−0.88) |
95% | 464 | 535 | 0.87 (0.78−0.96) | 95% | 214 | 285 | 0.75 (0.61−0.89) |
90% | 703 | 770 | 0.91 (0.84−0.98) | 90% | 203 | 270 | 0.75 (0.61−0.89) |
85% | 941 | 1005 | 0.94 (0.88−1.00) | 85% | 191 | 255 | 0.75 (0.60−0.90) |
80% | 1180 | 1240 | 0.95 (0.90−1.00) | 80% | 180 | 240 | 0.75 (0.59−0.91) |