Table 1. Summary of NNT, NNH, and ARR Reporting in Controlled Clinical Trials From 6 Widely Cited General Medical Journals.
| Journal by year | All trials (n = 875) | Trials with a statistically significant result (n = 624)a | Trials without a statistically significant result (n = 251)a | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total | No. (%) of trials with at least 1 reported | Total | No. (%) of trials with at least 1 reported | Total | No. (%) of trials with at least 1 reported | |||||||
| NNT | NNH | ARR | NNT and/or NNH | NNT, NNH, and/or ARR | NNT and/or NNH | NNT, NNH, and/or ARR | NNT and/or NNH | NNT, NNH, and/or ARR | ||||
| 2001 | ||||||||||||
| NEJM | 57 | 3 (5.3) | 0 | 7 (12.3) | 3 (5.3) | 9 (15.8) | 51 | 3 (5.9) | 9 (17.6) | 6 | 0 | 0 |
| Lancet | 21 | 2 (9.5) | 0 | 5 (23.8) | 2 (9.5) | 6 (28.6) | 16 | 2 (12.5) | 4 (25.0) | 5 | 0 | 2 (40.0) |
| JAMA | 27 | 2 (7.4) | 1 (3.7) | 2 (7.4) | 2 (7.4) | 3 (11.1) | 20 | 1 (5.0) | 2 (10.0) | 7 | 1 (14.3) | 1 (14.3) |
| BMJ | 20 | 3 (15.0) | 0 | 9 (45.0) | 3 (15.0) | 10 (50.0) | 13 | 3 (23.1) | 9 (69.2) | 7 | 0 | 1 (14.3) |
| JAMA IM | 10 | 2 (20.0) | 0 | 2 (20.0) | 2 (20.0) | 4 (40.0) | 7 | 2 (28.6) | 3 (42.9) | 3 | 0 | 1 (33.3) |
| Annals IM | 5 | 0 | 0 | 1 (20.0) | 0 | 1 (20.0) | 5 | 0 | 1 (20.0) | 0 | 0 | 0 |
| Total | 140 | 12 (8.6) | 1 (0.7) | 26 (18.6) | 12 (8.6) | 33 (23.6) | 112 | 11 (9.8) | 28 (25.0) | 28 | 1 (3.6) | 5 (17.9) |
| 2007 | ||||||||||||
| NEJM | 72 | 5 (6.9) | 0 | 17 (23.6) | 5 (6.9) | 18 (25.0) | 61 | 5 (8.2) | 16 (26.2) | 11 | 0 | 2 (18.2) |
| Lancet | 46 | 4 (8.7) | 1 (2.2) | 14 (30.4) | 4 (8.7) | 16 (34.8) | 35 | 4 (11.4) | 13 (37.1) | 11 | 0 | 3 (27.3) |
| JAMA | 31 | 5 (16.1) | 0 | 5 (16.1) | 5 (16.1) | 7 (22.6) | 15 | 4 (26.7) | 5 (33.3) | 16 | 1 (6.3) | 2 (12.5) |
| BMJ | 25 | 6 (24.0) | 0 | 6 (24.0) | 6 (24.0) | 8 (32.0) | 22 | 6 (27.3) | 7 (31.8) | 3 | 0 | 1 (33.3) |
| JAMA IM | 20 | 0 | 0 | 4 (20.0) | 0 | 4 (20.0) | 19 | 0 | 3 (15.8) | 1 | 0 | 1 (100) |
| Annals IM | 18 | 1 (5.6) | 0 | 12 (66.7) | 1 (5.6) | 12 (66.7) | 13 | 1 (7.7) | 8 (61.5) | 5 | 0 | 4 (80.0) |
| Total | 212 | 21 (9.9) | 1 (0.5) | 58 (27.4) | 21 (9.9) | 65 (30.7) | 165 | 20 (12.1) | 52 (31.5) | 47 | 1 (2.1) | 13 (27.7) |
| 2013 | ||||||||||||
| NEJM | 85 | 6 (7.1) | 0 | 15 (17.6) | 6 (7.1) | 18 (21.2) | 62 | 6 (9.7) | 15 (24.2) | 23 | 0 | 3 (20.0) |
| Lancet | 64 | 4 (6.3) | 1 (1.6) | 17 (26.6) | 5 (7.8) | 22 (34.4) | 42 | 5 (11.9) | 16 (38.1) | 22 | 0 | 6 (37.5) |
| JAMA | 41 | 5 (12.2) | 0 | 11 (26.8) | 5 (12.2) | 14 (34.2) | 25 | 5 (20.0) | 9 (36.0) | 16 | 0 | 5 (31.3) |
| BMJ | 20 | 1 (5.0) | 0 | 4 (20.0) | 1 (5.0) | 5 (25.0) | 11 | 0 | 2 (18.2) | 9 | 1 (11.1) | 3 (33.3) |
| JAMA IM | 15 | 4 (26.7) | 0 | 3 (20.0) | 4 (26.7) | 5 (33.0) | 12 | 3 (25.0) | 4 (33.3) | 3 | 1 (33.3) | 1 (33.3) |
| Annals IM | 16 | 0 | 0 | 10 (62.5) | 0 | 10 (62.5) | 11 | 0 | 5 (45.5) | 5 | 0 | 5 (100) |
| Total | 241 | 20 (8.3) | 1 (0.4) | 60 (24.9) | 21 (8.7) | 74 (30.7) | 163 | 19 (11.7) | 51 (31.3) | 78 | 2 (2.6) | 23 (29.5) |
| 2019 | ||||||||||||
| NEJM | 115 | 9 (7.8) | 3 (2.6) | 25 (21.7) | 10 (8.7) | 31 (27.0) | 79 | 10 (12.7) | 25 (31.6) | 36 | 0 | 6 (16.7) |
| Lancet | 86 | 10 (11.6) | 2 (2.3) | 32 (37.2) | 12 (14.0) | 38 (44.2) | 60 | 11 (18.3) | 34 (56.7) | 26 | 1 (3.8) | 4 (15.4) |
| JAMA | 61 | 0 | 0 | 42 (68.9) | 0 | 42 (68.9) | 32 | 0 | 23 (71.9) | 29 | 0 | 19 (65.6) |
| BMJ | 9 | 2 (22.2) | 0 | 2 (22.2) | 2 (22.2) | 3 (33.3) | 6 | 2 (33.3) | 2 (33.3) | 3 | 0 | 1 (33.3) |
| JAMA IM | 7 | 2 (28.6) | 0 | 0 | 2 (28.6) | 2 (28.6) | 6 | 2 (33.3) | 2 (33.3) | 1 | 0 | 0 |
| Annals IM | 4 | 0 | 0 | 4 (100) | 0 | 4 (1.0) | 1 | 0 | 1 (100) | 3 | 0 | 3 (100) |
| Total | 282 | 23 (8.2) | 5 1.8) | 105 (37.2) | 26 (9.2) | 120 (42.6) | 184 | 25 (13.6) | 87 (47.4) | 98 | 1 (1.0) | 33 (33.7) |
| All years | 875 | 76 (8.7) | 8 (0.9) | 249 (28.5) | 80 (9.1) | 292 (33.4) | 624 | 75 (12.0) | 218 (34.9) | 251 | 5 (2.0) | 74 (29.5) |
Abbreviations: Annals IM, Annals of Internal Medicine; ARR, absolute risk reduction; BMJ, British Medical Journal; JAMA, Journal of the American Medical Association; JAMA IM, JAMA Internal Medicine (formerly Archives of Internal Medicine); NEJM, New England Journal of Medicine; NNH, number needed to harm; NNT, number needed to treat.
a
At least 1 statistically significant (P < .05) finding for a binary efficacy or safety outcome or a hazard ratio reported in the abstract of a trial.