Comparison of author contributions by gender, stratified by the year of publication
| Variables | 2000 | 2015 | Change in gender differences over time (P value *) | ||||
| Women (n=243, 31.5%) | Men (n=528) | P value | Women (n=469, 41.2%) | Men (n=670) | P value | ||
| Contributions in the paper, n (%) | |||||||
| Conception and design | 134 (55.1) | 323 (61.2) | 0.03 | 223 (47.6) | 372 (55.5) | 0.001 | 0.81 |
| Analysis and interpretation of the data | 176 (72.4) | 362 (68.6) | 0.78 | 342 (72.9) | 496 (74.0) | 0.22 | 0.58 |
| Drafting of the article | 110 (45.3) | 206 (39.0) | 0.35 | 222 (47.3) | 298 (44.5) | 0.61 | 0.67 |
| Critical revision of the article for important intellectual content | 171 (70.4) | 426 (80.7) | <0.001 | 317 (67.6) | 535 (79.9) | <0.001 | 0.94 |
| Provision of materials/patients | 106 (43.6) | 244 (46.2) | 0.75 | 98 (20.9) | 178 (26.6) | 0.05 | 0.29 |
| Obtaining of funding | 39 (16.1) | 114 (21.6) | 0.02 | 66 (14.1) | 134 (20.0) | <0.001 | 0.60 |
| Statistical expertise | 49 (20.2) | 125 (23.7) | 0.24 | 103 (22.0) | 157 (23.4) | 0.56 | 0.60 |
| Administrative, technical and logistic support | 85 (35.0) | 137 (26.0) | 0.02 | 147 (31.3) | 178 (26.6) | 0.27 | 0.25 |
| Collection and assembly of data | 121 (49.8) | 242 (45.8) | 0.05 | 260 (55.4) | 306 (45.7) | 0.008 | 0.90 |
| Final approval of the article | 196 (80.7) | 453 (85.8) | 0.04 | 404 (86.1) | 602 (89.9) | 0.08 | 0.69 |
| Author position, n (%) | 0.01 | 0.003 | 0.84 | ||||
| First | 35 (14.4) | 69 (13.1) | 55 (11.7) | 74 (11.0) | |||
| Second | 40 (16.5) | 51 (9.7) | 51 (10.9) | 56 (8.4) | |||
| Middle | 117 (48.1) | 256 (48.5) | 290 (61.8) | 377 (56.3) | |||
| Next-to-last | 29 (11.9) | 70 (13.3) | 40 (8.5) | 77 (11.5) | |||
| Last | 22 (9.0) | 82 (15.5) | 33 (7.0) | 86 (12.8) | |||
*P value testing an interaction between each variable listed and the year in the assessment of gender differences. All p values are obtained from mixed-effects logistic regression models.