Reported article items over the study period
| Reported items | Year | P value | ||||
| 1997 n=296* | 2002 n=311* | 2007 n=382* | 2012 n=587* | 2017 n=576* | ||
| Study title acronym n, % (95% CI) | 20 6.8 (4.3 to 10.4) | 47 15.1 (11.4 to 19.7) | 43 11.3 (8.4 to 15.0) | 90 15.3 (12.6 to 18.6) | 128 22.2 (18.9 to 25.9) | <0.001 |
| Keywords n, % (95% CI) | 20 6.8 (4.3 to 10.4) | 73 23.5 (19.0 to 28.7) | 88 23.0 (19.0 to 27.7) | 177 30.2 (26.5 to 34.1) | 316 54.9 (50.7 to 59.0) | <0.001 |
| Ethics approval n, % (95% CI) | 170 54.9 (50.7 to 59.0) | 223 71.7 (66.3 to 76.6) | 298 78.2 (73.7 to 82.2) | 519 88.7 (85.8 to 91.1) | 531 92.2 (89.6 to 94.2) | <0.001 |
| Funded study n, % (95% CI) | 55 18.6 (14.4 to 23.6) | 84 27.0 (22.2 to 32.4) | 104 27.2 (22.9 to 32.0) | 250 43.3 (39.2 to 47.4) | 237 41.2 (37.1 to 45.3) | <0.001 |
| Conflict of interest n, % (95% CI) | 0 0.0 (0.0 to 1.6) | 31 10.0 (7.0 to 14.0) | 145 38.0 (33.1 to 43.1) | 480 81.9 (78.5 to 84.9) | 490 85.1 (81.8 to 87.8) | <0.001 |
| Author contribution n, % (95% CI) | 2 0.7 (0.1 to 2.7) | 104 33.4 (28.3 to 39.0) | 96 25.1 (20.9 to 29.9) | 196 33.4 (29.6 to 37.4) | 273 47.4 (43.3 to 51.6) | <0.001 |
| Female first author n, % (95% CI) | 62 24.3 (19.3 to 30.1) | 70 26.7 (21.6 to 32.6) | 111 30.8 (26.1 to 35.9) | 199 35.9 (31.9 to 40.0) | 188 34.2 (30.3 to 38.3) | 0.004 |
*Some denominators vary due to missing data.