Table 1.
Characteristics of trials using surrogate primary outcomes and final patient relevant primary outcomes. Values are numbers (percentages) unless stated otherwise
| Characteristics | Surrogate outcomes (n=84) | Patient relevant outcomes (n=101) |
|---|---|---|
| Intervention clinical area: | ||
| Cardiovascular | 20 (24) | 25 (25) |
| Endocrinology | 4 (5) | 3 (3) |
| Gastrology and hepatology | 9 (11) | 10 (10) |
| Infectious disease | 18 (21) | 21 (21) |
| Nephrology and urology | 1 (1) | 4 (4) |
| Neurology | 0 (0) | 2 (2) |
| Obstetrics | 5 (6) | 4 (4) |
| Oncology | 5 (6) | 2 (2) |
| Other | 17 (20) | 24 (23) |
| Pulmonology | 5 (6) | 6 (6) |
| Population clinical area: | ||
| Cardiovascular | 25 (30) | 25 (25) |
| Endocrinology | 4 (5) | 7 (7) |
| Gastrology and hepatology | 8 (10) | 9 (9) |
| Infectious disease | 13 (15) | 15 (14) |
| Nephrology and urology | 0 (0) | 5 (5) |
| Neurology | 0 (0) | 1 (1) |
| Obstetrics | 7 (8) | 7 (7) |
| Oncology | 5 (6) | 2 (2) |
| Other | 16 (19) | 25 (25) |
| Pulmonology | 6 (7) | 5 (5) |
| Journal: | ||
| Annals of Internal Medicine | 8 (10) | 6 (6) |
| BMJ | 7 (8) | 11 (11) |
| Journal of the American Medical Association | 20 (24) | 22 (22) |
| Lancet | 21 (25) | 19 (19) |
| New England Journal of Medicine | 27 (32) | 42 (41) |
| PLoS Medicine | 1 (1) | 1 (1) |
| Publication year: | ||
| 2005 | 40 (48) | 49 (49) |
| 2006 | 44 (52) | 52 (51) |
| Centre status: | ||
| Single centre | 19 (23) | 9 (9)* |
| Multicentre | 65 (77) | 92 (91)* |
| Intervention: | ||
| Drugs | 49 (59) | 61 (60) |
| Medical devices | 7 (8) | 7 (7) |
| Surgical procedures | 4 (5) | 8 (8) |
| Health promotion activities | 7 (8) | 2 (2) |
| Other therapeutic technologies | 17 (20) | 23 (23) |
| Sponsor: | ||
| Profit | 24 (29) | 29 (29) |
| Not for profit | 49 (59) | 56 (55) |
| Mixed | 11 (12) | 16 (16) |
| Median (interquartile range) sample size | 371 (162-787) | 741 (300-4731)† |
| Median (interquartile range) follow-up (days) | 255 (133-540) | 180 (35-730) |
*χ2 test, P=0.01.
†Mann-Whitney U test, P<0.001.