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Table 1 Number and proportion of Cochrane reviews included, trials missing data for specific domains, trials observed and judgments analyzed in total and according to types of intervention

From: Adequacy of risk of bias assessment in surgical vs non-surgical trials in Cochrane reviews: a methodological study

   Domain I (random sequence generation) Domain II (allocation concealment) Domain III + a (blinding of participants and personnel) Domain IV + a (blinding of outcome assessors)
Reviews included (from original 729 reviews) Surgical studies N (% of included) 77 (10.9%) 79 (10.7%) 72 (10.5%) 79 (11.0%)
Non-surgical studies N (% of included) 652 (92.0%) 659 (89.3%) 613 (89.5%) 642 (89.0%)
Total N (%) 709 (97.3%) 717 (98.4%) 685 (94.0%) 721 (98.9%)
Studies with domain missing (from original 10,537 studies) Surgical N (%) 37 (0.4%) 28 (0.3%) 54 (0.5%) 16 (0.2%)
Non-surgical N (%) 402 (3.8%) 329 (3.1%) 752 (7.1%) 417 (4.0%)
Overall N (%) 439 (4.2%) 357 (3.4%) 806 (7.6%) 433 (4.1%)
Studies observed (from original 10,537 studies) Surgical N (%) 778 (7.4%) 789 (7.5%) 761 (7.2%) 808 (7.7%)
Non-surgical N (%) 9320 (88.5%) 9391 (89.1%) 8970 (85.1%) 9296 (88.2%)
Overall N (%) 10,098 (95.8%) 10,180 (96.6%) 9731 (92.4%) 10,104 (95.9%)
Judgments analyzed (from number of observed studies in domain) Surgical N (%) 778 (7.7%) 789 (7.7%) 945 (8.4%) 924 (7.8%)
Non-surgical N (%) 9325 (92.3%) 9459 (92.3%) 10,266 (91.6%) 10,957 (92.2%)
Surgical + N (+%)b 0 (+ 0.0%) 0 (+ 0.0%) 184 (+ 19.5%) 116 (+ 12.6%)
Non-surgical + N (+%)b 5 (+ 0.1%) 68 (+ 0.7%) 1296 (+ 12.6%) 1661 (+ 15.2%)
Overall N (+%)b 10,103 (+ 0.0%) 10,248 (+ 0.7%) 11,211 (+ 13.2%) 11,881 (+ 15.0%)
  1. aAlso includes data for joint domain of blinding of participants, personnel, and outcome assessor
  2. bCochrane authors provided additional multiple judgments (for different outcomes)