| Variable | Citation impact metric; median (IQR) | ||
|---|---|---|---|
| Journal impact factor in 2012 | No. of citations per RCD study per year | Total no. of citations per RCD study | |
| All studies (n = 337)* | 4.5 (3.2-11) | 4.0 (1.5-8.0) | 22 (9-55) |
| RCT evidence mentioned or cited | |||
| No (n = 124)* | 4.5 (3.5-11) | 4.6 (2.5-9.3) | 29 (13-61) |
| Yes (n = 213)* | 4.5 (3.2-11) | 3.0 (1.3-7.5) | 19 (8-49) |
| p value | 0.2 | 0.01 | 0.01 |
| RCTs existed before publication | |||
| No (n = 106)* | 4.5 (3.5-11) | 4.2 (2.3-8) | 26 (12-58) |
| Yes (n = 231)* | 4.5 (3.2-11) | 3.5 (1.3-7.9) | 20 (8-53) |
| p value | 0.2 | 0.1 | 0.09 |
| Studies with RCT-related research motivation (n = 213)† | |||
| Assess effects in the "real world" | |||
| Yes | 3.9 (2.9-6.5) | 1.9 (0.95-5.2) | 11 (5-36) |
| No | 4.7 (3.2-14) | 4.4 (1.9-9.6) | 24 (10-60) |
| p value | 0.08 | < 0.001 | 0.002 |
| Assess different outcomes | |||
| Yes | 5.0 (3.5-14) | 4.7 (2-13) | 24 (10-76) |
| No | 4.1 (3.1-9.1) | 2.3 (1.3-6) | 17 (7-36) |
| p value | 0.1 | 0.01 | 0.06 |
| RCT evidence inconclusive or inconsistent | |||
| Yes | 4.8 (2.9-9.1) | 3.0 (1.3-6.6) | 14 (6-38) |
| No | 4.1 (3.2-14) | 3.1 (1.3-8) | 19 (8-54) |
| p value | 0.9 | 0.7 | 0.3 |
| Study specific patient population | |||
| Yes | 5.0 (3.2-14) | 2.3 (1.3-5.4) | 18 (7-38) |
| No | 4.5 (3.2-11) | 3.1 (1.3-8) | 19 (8-52) |
| p value | 0.7 | 0.4 | 0.4 |
| Other | |||
| Yes | 4.5 (3.6-13) | 3.7 (1.6-9.2) | 22 (9-55) |
| No | 4.5 (3.2-11) | 2.8 (1.3-7.3) | 18 (8-47) |
| p value | 0.2 | 0.4 | 0.4 |
| No RCT-related motivation | |||
| Yes | 3.5 (3.2-6.2) | 5.0 (2.2-11) | 29 (18-48) |
| No | 4.5 (3.2-14) | 2.9 (1.2-7.3) | 18 (7-52) |
| p value | 0.6 | 0.09 | 0.06 |
Note: IQR = interquartile range, RCT = randomized controlled trial.
*Data on number of citations were missing for 3 studies; there was no impact factor available for 6 studies.
†Studies mentioning or citing RCT evidence; for study details, see Appendix 4 (available at www.cmajopen.ca/content/4/2/E132/suppl/DC1).