Table 3.
Adherence (number (percentage)) to standard criteria for reporting and methodology for cluster randomised trials, overall and before and after publication of CONSORT extension for cluster randomised trials
| Overall (n=300) | Before (2000-4, n=139) | After (2005-6, n=93) | After (2007-8, n=68) | P value for trend | Absolute change in % adherence (before to after) (95% CI) | |
|---|---|---|---|---|---|---|
| Criteria related to quality of reporting | ||||||
| Clearly identified as clustered in title or abstract | 145 (48) | 59 (43) | 47 (50.5) | 39 (57) | 0.038 | 11.0 (−0.3 to 22.2) |
| Justification provided for using cluster design | 94 (31) | 37 (27) | 29 (31.2) | 28 (41) | 0.038 | 8.8 (−1.6 to 19.2) |
| Reported on blinding of outcome assessors | 113 (38) | 42 (30) | 40 (43.0) | 31 (46) | 0.019 | 13.9 (3.1 to 24.7) |
| Reported on blinding of participants/administrators | 151 (50) | 72 (52) | 50 (53.8) | 29 (43) | 0.292 | −2.7 (−14.1 to 8.6) |
| Primary outcome identified clearly | 141 (47) | 62 (45) | 43 (46.2) | 36 (53) | 0.284 | 4.5 (−6.9 to 15.8) |
| Sample size calculation presented | 164 (55) | 77 (55) | 44 (47.3) | 43 (63) | 0.483 | −1.4 (−12.7 to 9.9) |
| Identified who enrolled participants* | 134 (58) | 59 (60) | 41 (55.4) | 34 (57) | 0.674 | −3.6 (−16.4 to 9.2) |
| Reported No of clusters randomised | 261 (87) | 116 (84) | 81 (87.1) | 64 (94) | 0.035 | 6.6 (−1.1 to 14.3) |
| Reported No of clusters lost to follow-up | 235 (78) | 99 (71) | 78 (83.9) | 58 (85) | 0.010 | 13.3 (3.9 to 22.6) |
| Reported No of clusters that withdrew | 256 (85) | 115 (83) | 78 (83.9) | 63 (93) | 0.078 | 4.8 (−3.3 to 12.9) |
| Reported size of clusters in each arm | 262 (87) | 117 (84) | 82 (88.2) | 63 (93) | 0.081 | 5.9 (−1.7 to 13.5) |
| Reported No of individuals lost to follow-up | 228 (76) | 109 (78) | 65 (69.9) | 54 (79) | 0.860 | −4.5 (−14.1 to 5.1) |
| Reported methods of analysis | 281 (94) | 128 (92) | 89 (95.7) | 64 (94) | 0.456 | 2.9 (−2.7 to 8.6) |
| Reported intracluster correlation† | 35 (16) | 21 (22) | 4 (6.2) | 10 (18) | 0.323 | −10.2 (−20.3 to 0) |
| Mean (SD) summary score | 61.8 (19.2) | 59.9 (19.6) | 61.5 (19.9) | 66.1 (16.9) | 0.092 | 3.5 (−0.8 to 7.8) |
| Criteria relating to methodological quality | ||||||
| Used restricted randomisation | 167 (56) | 72 (52) | 55 (59.1) | 40 (59) | 0.272 | 7.2 (−4.1 to 18.5) |
| Allocated minimum of four clusters per arm‡ | 244 (86) | 111 (85) | 76 (85.4) | 57 (86) | 0.867 | 0.4 (−7.8 to 8.6) |
| Accounted for clustering in sample size§ | 100 (61) | 51 (66) | 21 (47.7) | 28 (65) | 0.662 | −9.9 (−24.8 to 4.9) |
| Accounted for clustering in analysis | 209 (70) | 100 (72) | 63 (67.7) | 46 (68) | 0.474 | −4.2 (−14.6 to 6.2) |
*Excludes 67 trials with no participant enrolment.
†Excludes 84 trials with pair matched designs or primary analysis at cluster level.
‡Excludes 15 studies with unclear number of clusters.
§Excludes 136 trials with no sample size calculation presented.