Table 2. Trial Design of 388 Included Trials.
| Variable | Frequency, No. (%) |
|---|---|
| Registration in trials registry | 242 (62.4) |
| Discrepancy between registered and primary outcome | 81 (33.5) |
| Superiority design | 329 (84.8) |
| Power, median (IQR), % | 80.0 (80.0-90.0) |
| Estimated relative treatment effect, median (IQR), % | 50.0 (24.7-63.3) |
| Estimated treatment effect of trials with a major clinical end point as primary outcome | 50.0 (24.5-67.9) |
| Estimated treatment effect of trials with a minor clinical end point as primary outcome | 46.6 (25.0-57.1) |
| Intention-to-treat as the primary analysis | 221 (56.9) |
| Noninferiority design | 55 (14.2) |
| Both noninferiority and superiority design | 3 (0.8) |
| Use of composite primary outcome | 82 (21.1) |
| Major clinical event as primary end point | 123 (31.7) |
| No. of patients screened, median (IQR) | 204 (105-465) |
| Sample size, median (IQR) | |
| Projected | 144 (86-299) |
| Final | 122 (70-245) |
| Duration of follow-up, median (IQR), mo | 24.0 (12.0, 32.0) |
| Type of primary outcome | |
| Time to event | 181 (46.7) |
| Quality of life | 50 (12.8) |
| Other scales | 157 (40.5) |
| Randomization | |
| Computer generated | 213 (54.9) |
| Envelope | 90 (23.2) |
| Random number table | 36 (9.3) |
| Telephone call to randomization center | 10 (2.6) |
| Drawing of lots | 2 (0.5) |
| Date of birth | 2 (0.5) |
| Flip of a coin | 1 (0.3) |
| No details given | 34 (8.7) |
| Blinding | |
| None | 74 (19.1) |
| Outcome assessor only | 61 (15.7) |
| Patient and outcome assessor | 60 (15.4) |
| Patient only | 32 (8.3) |
| Patient, outcome assessor, data analyst | 18 (4.6) |
| Outcome assessor and data analyst | 8 (2.1) |
| Data analyst only | 6 (1.5) |
| Patient, surgeon, outcome assessor, data analyst | 1 (0.3) |
| No details given | 128 (33.0) |
| Control for surgeons’ experience | |
| None | 303 (78.1) |
| Surgeons’ experience cut-off | 60 (15.5) |
| Pretrial training | 25 (6.4) |
| Monitoring of the intervention | |
| None | 371 (95.6) |
| Photo | 4 (1.0) |
| Video | 9 (2.3) |
| Site visit | 3 (0.8) |
| Data monitoring of outcomes | 1 (0.3) |
| Details of the experimental procedure | |
| None | 41 (10.6) |
| Limited | 226 (58.2) |
| Detailed | 121 (31.2) |
| Risk of bias assessment | |
| Low risk | 86 (22.2) |
| Some concerns | 211 (54.4) |
| High risk | 91 (23.5) |
| Funding | |
| External | 288 (74.2) |
| Industry | 96 (33.3) |
| Industry sponsor involved in the analysis | 51 (53.1) |
| Conflicts of interest | |
| First author with study sponsor | 34 (35.4) |
| Last author with study sponsor | 29 (30.2) |
| PRECIS-2 score, mean (SD)a | 3.52 (0.65) |
Abbreviations: IQR, interquartile range; PRECIS-2, Pragmatic Explanatory Continuum Indicator Summary 2.
a
PRECIS-2 uses a 5-point ordinal scale (ranging from very pragmatic to very explanatory) across 9 domains of trial design, including eligibility, recruitment, setting, organization, intervention delivery, intervention adherence, follow-up, primary outcome, and analysis.