Measure chosen | Gold standard | Acceptable change from gold standard | Time point(s) to assess at | Maximum NNF* |
Total h ip/ k nee r eplacement | ||||
Harris Hip Score/Knee Society Score | Postoperative score at year 2 | 4 points or d=0.3 | 5 and 10 years | 341 |
QoL | Preoperative score | THR: 1.4, 2.4 points or d=0.3, 0.5 TKR: 1.6, 2.7 points or d=0.3, 0.5 | 1 year | 181 |
Revision | Annual rate of 0.5% | OR=1.5 | 5 and 10 years | 2500 |
EVAR | ||||
Endoleak | Annual rate of 2.8% | OR=1.5 | 2 and 5 years | 1400 |
30-day all-cause mortality | 2% | OR=1.5 | 30 days | 2200 |
Secondary vascular intervention | Annual rate of 4% | OR=1.5 | 4 and 6 years | 450 |
Surgical mesh for POP | ||||
Erosion | 6% | OR=1.5 | 1 year | 800 |
QoL | Preoperative score | 8.6, 14.4 points or d=0.3, 0.5 | 1 year | 181 |
Total reoperation rate | 3%–4% | OR=1.5 | 1 year | 1500 |
The gold standard for continuous outcomes is based on a baseline measure (before surgery or 2 years after surgery) and that for binary outcomes is based on gold standard rates from literature or expert opinion.
*The maximum is over multiple scenarios of gold standards and time points.
EVAR, endovascular aneurysm repair; POP, pelvic organ prolapse; QoL, quality of life;THR, total hip replacement; TKR, total knee replacement; d, Cohen’s d.