Table 2.
Randomization methods used in the included trials (N = 160)
| Characteristic | Frequency (%) |
|---|---|
|
| |
| Allocation strategy | |
| Unrestricted randomization | 96 (60.0) |
| Some restricted randomization method | 63 (39.4) |
| Stratification | 37 (58.7) |
| Matching | 10 (15.9) |
| Minimization | 2 (3.2) |
| Covariate-constrained randomization | 4 (6.3) |
| Other, mixture, or precise details not stated | 10 (15.9) |
| No details of randomization | 1 (0.6) |
| Number of inherently cluster-level characteristics used in randomization (N = 63 with restricted randomization) | |
| 0 | 2 (3.2) |
| 1 | 43 (68.3) |
| >1 | 16 (25.4) |
| Unclear | 2 (3.2) |
| Min, Max | 0, 7 |
| Type of cluster-level characteristics balanced during allocationa (N = 59 with at least one cluster-level characteristic) | |
| Cluster size | 31 (49.2) |
| Cluster location | 25 (39.7) |
| Other (e.g., practice type) | 22 (34.9) |
| Number of inherently individual-level characteristics used in randomization (N = 63) | |
| 0 | 59 (93.7) |
| 1 | 2 (3.2) |
| Unclear | 2 (3.2) |
| Justification provided for restricting randomization by chosen variable(s) (N = 63) | |
| Yes, for at least one | 27 (42.9) |
| No | 36 (57.1) |
| Covariates used in restricted randomization adjusted in the primary analysis? (N = 63 with restricted randomization) | |
| Yes, some or all | 12 (19.0) |
| All identical in scale and level | 10 (15.9) |
| Change in at least one in terms of scale and/or level | 1 (1.6) |
| Unclear if same scale and/or level | 1 (1.6) |
| No | 49 (77.8) |
| Unclear | 2 (3.2) |
a
Not mutually exclusive categories, multiple selections possible.