Table 1.
Descriptive statistics
| All | Adequate | Inadequate methods | Poor reporting | |
| Sample 1, (%) | 20 571 (100) | 1173 (5.7) | 12 190 (59.3) | 7208 (35.0) |
| Sample 2 (with full text) | 11 686 (56.8) | 833 (7.1) | 6783 (58.0) | 4070 (34.8) |
| Funder type, (%) | ||||
| NIH grant | 2147 (10.4) | 146 (6.8) | 1282 (59.7) | 719 (33.5) |
| Industry funding | 2725 (13.2) | 283 (10.2) | 1464 (52.6) | 978 (35.1) |
| First author affiliation, (%) | ||||
| Top university | 1063 (5.2) | 51 (4.8) | 601 (56.5) | 411 (38.7) |
| Other university | 11 120 (54.1) | 677 (6.1) | 6589 (59.3) | 3854 (34.7) |
| Hospital | 4450 (21.6) | 185 (4.2) | 2608 (58.6) | 1657 (37.2) |
| Government | 1744 (8.5) | 108 (6.2) | 1071 (61.4) | 565 (32.4) |
| Non-profit | 751 (3.7) | 48 (6.4) | 454 (60.5) | 249 (33.2) |
| Top pharma | 239 (1.2) | 26 (10.9) | 115 (48.1) | 98 (41.0) |
| Other firm | 195 (1.0) | 13 (6.7) | 115 (59.0) | 67 (34.3) |
| Other research institution | 200 (1.0) | 18 (9.0) | 120 (60.0) | 62 (31.0) |
| Other industry affiliation | 570 (2.8) | 44 (7.7) | 287 (50.4) | 239 (41.9) |
| Registered RCTs (NCT), (%) | 1888 (9.2) | 298 (15.8) | 1011 (53.6) | 579 (30.7) |
| Novelty, (%) | ||||
| First study | 2284 (11.1) | 126 (5.5) | 1390 (60.9) | 768 (33.6) |
| Second study | 2124 (10.3) | 127 (6.0) | 1262 (59.4) | 735 (34.6) |
| Team characteristics | ||||
| No of authors—avg (Std) | 6.15 (3.9) | 8.04 (5.5) | 5.99 (3.8) | 6.13 (6.8) |
| International, (%) | 748 (3.6) | 60 (8.0) | 379 (50.7) | 309 (41.3) |
| Technology*, (%) | ||||
| Drug | 13 485 (65.6) | 914 (6.8) | 7306 (54.2) | 5265 (39.0) |
| Device | 5347 (26.0) | 235 (4.4) | 3366 (63.0) | 1746 (32.7) |
| Procedure | 8710 (42.3) | 460 (5.3) | 4925 (56.5) | 3325 (38.2) |
| Behavioural | 4543 (22.1) | 122 (2.7) | 3239 (71.3) | 1182 (26.0) |
| Other | 1199 (5.8) | 78 (6.5) | 819 (68.3) | 302 (25.2) |
| Geography†, (%) | ||||
| Canada | 680 (3.3) | 61 (9.0) | 362 (53.2) | 257 (37.8) |
| Europe | 4467 (21.7) | 254 (5.7) | 2693 (60.3) | 1520 (34.0) |
| UK | 2306 (11.2) | 154 (6.7) | 1399 (60.7) | 753 (32.7) |
| USA | 4465 (21.7) | 284 (6.4) | 2592 (58.1) | 1589 (35.6) |
| Other | 4165 (20.3) | 253 (6.1) | 2444 (58.7) | 1468 (35.3) |
| Publication year—avg (Std) | 2001 (10.2) | 2005 (8.1) | 2001 (10.4) | 2001 (9.9) |
| Study age at review—avg (Std) | 13.44 (10.1) | 9.81 (8.0) | 13.39 (10.3) | 14.14 (9.9) |
Unless otherwise specified, column 1 reports the number of RCTs and their proportion as of the total number of RCTs (n=20 571). An RCT uses adequate methods if it is at ‘low risk of bias’ on all six dimensions assessed (see online supplementary table A1). Methods are inadequate if an RCT is at ‘high risk of bias’ for at least one reason. Methods are poorly reported if there is no evidence of methods inadequacy, but at least one assessment is ‘unclear risk of bias’. Columns 2–4 report the number of RCTs in each category and their proportion as of the number of RCTs in column 1. For number of authors, publication year and study age at time of review, table 1 reports the average and standard deviation.
*One RCT can belong to several technology categories.
†For some RCTs, affiliation address is not provided.
NCT, National clinical Trial number in ClinicalTrials.gov; NIH, National Institutes of Health; RCT, randomised controlled trial.