The collection and reporting of information about missing participant data in Cochrane and non-Cochrane SRs
| Overall (N=202) | Cochrane SR (N=98) | Non-Cochrane SR (N=104) | p Value* | |
|---|---|---|---|---|
| Reported a plan to collect number of participants with missing data | 68 (33.7%) | 51 (52%) | 17 (16.3%) | <0.0001 |
| Reported a plan to collect reasons for missing data | 35 (17.3%) | 26 (26.5%) | 9 (8.7%) | 0.0008 |
| Reported number of participants with missing data | ||||
| No | 149 (73.8%) | 52 (53.1%) | 97 (93.3%) | <0.0001 |
| Across comparisons, but not for each comparison | 14 (7.0%) | 11 (11.2%) | 3 (2.9%) | 0.03 |
| For each comparison, but not for each study | 3 (1.5%) | 2 (2.0%) | 1 (1.0%) | 0.61 |
| For each study but not for each outcome | 34 (16.8%) | 31 (31.6%) | 3 (2.9%) | <0.0001 |
| For each outcome | 2 (1.0%) | 2 (2.0%) | 0 (0%) | 0.23 |
| Reported on the following participant categories with potentially missing data | ||||
| No reporting of any category | 163 (80.7%) | 66 (67.4%) | 97 (93.3%) | <0.0001 |
| Mistakenly randomised | 6 (3.0%) | 6 (6.1%) | 0 (0%) | 0.01 |
| Did not receive intervention | 4 (2.0%) | 4 (4.1%) | 0 (0%) | 0.05 |
| Withdrew consent | 12 (6.0%) | 11 (11.2%) | 1 (1.0%) | 0.002 |
| Crossed over | 0 (0%) | 0 (0%) | 0 (0%) | – |
| Dropped out | 21 (10.4%) | 16 (16.3%) | 5 (4.8%) | 0.007 |
| Non-adherent | 7 (3.5%) | 7 (7.1%) | 0 (0%) | 0.006 |
| Lost contact | 14 (6.9%) | 13 (13.3%) | 1 (1%) | <0.0001 |
| ‘Other reasons’ not otherwise specified | 6 (3.0%) | 5 (5.0%) | 1 (1.0%) | 0.11 |
| Other specified reason | 10 (5.0%) | 10 (10%) | 0 (0%) | <0.0001 |
| SR authors reported that included studies did not report on missing data | 3 (1.5%) | 3 (3.1%) | 0 (0%) | 0.11 |
| Reported on missing data as distinct outcome | 9 (4.5%) | 8 (8.2%) | 1 (1.0%) | 0.02 |
| Reported information on missing data in | ||||
| Cochrane RoB tool (table format) | 61 (30.2%) | 59 (60.2%) | 2 (1.9%) | <0.0001 |
| Cochrane RoB tool (graph format) | 46 (22.77%) | 45 (45.92%) | 1 (1.0%) | <0.0001 |
| GRADE SoF table | 9 (4.5%) | 9 (9.2%) | 0 (0.0%) | 0.001 |
| GRADE EP | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | – |
| Table describing characteristics of included studies | 70 (34.7%) | 61 (62.2%) | 9 (8.7%) | <0.0001 |
| Other table | 9 (4.5%) | 2 (2.0%) | 7 (6.7%) | 0.17 |
| None of the above | 102 (50.5%) | 17 (17.4%) | 85 (81.7%) | <0.0001 |
*p Value for the difference between Cochrane and non-Cochrane SRs.
EP, Evidence Profile; GRADE, Grading of Recommendations Assessment, Development and Evaluation; RoB, Risk of Bias; SoF, Summary of Findings; SR, systematic review.