Table 2 Assessment of methodology used to calculate number needed to treat (NNT) in included studies
From: Number needed to treat (NNT) in clinical literature: an appraisal
Meta-analysis (n = 23) | RCT (n = 17) | Cohort (n = 9) | Nested case–control (n = 2) | Overall (n = 51) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Methodology used to calculate NNT is defined in the methods section of the study | ||||||||||
Yes | 19 | 82.6%) | 0 | (0.0%) | 7 | (77.8%) | 2 | (100.0%) | 28 | (54.9%) |
No | 4 | 17.4%) | 17 | (100.0%) | 2 | (22.2%) | 0 | (0.0%) | 23 | (45.1%) |
General characteristics of the methodology used to calculate NNT in the study | ||||||||||
Reciprocal of risk difference | ||||||||||
Simple proportions | 1 | (4.3%) | 14 | (82.4%) | 2 | (22.2%) | 0 | (0.0%) | 17 | (33.3%) |
Cumulative IR | 0 | (0.0%) | 3 | (17.6%) | 3 | (33.3%) | 0 | (0.0%) | 6 | (11.8%) |
Pooled RD | 12 | (52.2%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 12 | (23.15) |
Average RD | 0 | (0.0%) | 0 | (0.0%) | 4 | (44.4%) | 0 | (0.0%) | 4 | (7.8%) |
Relative effect measure | 10 | (43.5%) | 0 | (0.0%) | 0 | (0.0%) | 2 | (100.0%) | 12 | (23.5%) |
Methodology used to calculate NNT is in line with basic recommendations (overall) | ||||||||||
Yes | 10 | (43.5%) | 16 | (94.1%) | 8 | (88.9%) | 2 | (100.0%) | 37 | (70.6%) |
No | 13 | (56.5%) | 1 | (5.9%) | 1 | (11.1%) | 0 | (0.0%) | 15 | (29.4%) |
Methodology used to calculate NNT is in line with basic recommendations (detailed) | ||||||||||
Binary variables | ||||||||||
Yes | 9 | (39.1%) | 13 | (76.5%) | 5 | (55.6%) | 1 | (50.0%) | 28 | (54.9%) |
Reciprocal of risk difference | ||||||||||
Simple proportions | 0 | (0.0%) | 13 | (76.5%) | 1 | (11.1%) | 0 | (0.0%) | 14 | (27.5%) |
Cumulative IR | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Pooled RD | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Average RD | 0 | (0.0%) | 0 | (0.0%) | 4 | (44.4%) | 0 | (0.0%) | 4 | (7.8%) |
Relative effect measure | 9 | (39.1%) | 0 | (0.0%) | 0 | (0.0%) | 1 | (50.0%) | 10 | (19.6%) |
No | 13 | (56.5%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 13 | (25.5%) |
Reciprocal of risk difference | ||||||||||
Simple proportions | 1 | (4.3%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 1 | (2.0%) |
Cumulative IR | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Pooled RD | 12 | (52.2%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 12 | (23.5%) |
Average RD | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Relative effect measure | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Time-to-event variables | ||||||||||
Yes | 1 | (4.3%) | 3 | (17.6%) | 3 | (33.3%) | 1 | (50.0%) | 8 | (15.7%) |
Reciprocal of risk difference | ||||||||||
Simple proportions | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Cumulative IR | 0 | (0.0%) | 3 | (17.6%) | 3 | (33.3%) | 0 | (0.0%) | 6 | (11.8%) |
Pooled RD | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Average RD | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Relative effect measure | 1 | (4.3%) | 0 | (0.0%) | 0 | (0.0%) | 1 | (50.0%) | 2 | (3.9%) |
No | 0 | (0.0%) | 1 | (5.9%) | 1 | (11.1%) | 0 | (0.0%) | 2 | (3.9%) |
Reciprocal of risk difference | ||||||||||
Simple proportions | 0 | (0.0%) | 1 | (5.9%) | 1 | (11.1%) | 0 | (0.0%) | 2 | (3.9%) |
Cumulative IR | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Pooled RD | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Average RD | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |
Relative effect measure | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) | 0 | (0.0%) |