Table 2.
Characteristics of 300 cluster randomised trials included in review of studies for compliance with CONSORT extension. Figures are numbers (percentage) of trials unless stated otherwise
| Characteristic | Data |
|---|---|
| Publication year: | |
| 2000-4 | 139 (46) |
| 2005-6 | 93 (31) |
| 2007-8 | 68 (23) |
| Journal impact factor (n=294): | |
| Median (IQR) | 2.9 (2.1-5.1) |
| Range | 0.45-50.0 |
| Country of study recruitment: | |
| USA | 114 (38) |
| UK or Ireland | 50 (17) |
| Canada | 16 (5) |
| Australia or New Zealand | 16 (5) |
| Other | 104 (35) |
| Clinical setting (unit of allocation): | |
| Medical practices or clinics | 81 (27) |
| Individual health professionals | 41 (14) |
| Hospitals, hospital units, hospital wards | 25 (8) |
| Nursing homes or wards | 16 (5) |
| Other (such as postal codes of family practices) | 6 (2) |
| Non-clinical setting (unit of allocation): | |
| Schools or classrooms | 66 (22) |
| Residential areas (such as villages, districts, housing units) | 39 (13) |
| Worksites | 16 (5) |
| Sports teams, clubs, churches, other social groups | 10 (3) |
| No of clusters randomised (n=285): | |
| Median (IQR) | 21.0 (12-52) |
| Range | 2-605 |
| Average cluster size (n=271): | |
| Median (IQR) | 33.9 (12.5-88.5) |
| Range | 1.7-122 855 |
| No of participants per arm (n=290): | |
| Median (IQR) | 329 (143-866) |
| Range | 20-614 275 |
IQR=interquartile range.