Characteristics of included studies
| Number of studies (n=67), n (%) | |
| Type of study | |
| RCT | 35 (52.2) |
| Follow-up RCT | 5 (7.5) |
| Prospective observational cohort | 7 (10.4) |
| Retrospective observational cohort | 19 (28.4) |
| Follow-up observational | 1 (1.5) |
| Mentioned PRO as | |
| Primary outcome | 33 (50.0) |
| Secondary outcome | 33 (50.0) |
| Mean follow-up | |
| 1–6 months | 15 (25.0) |
| 7–12 months | 23 (38.3) |
| 1–2 years | 12 (20.1) |
| 2–12 years | 10 (16.8) |
| Number of centres | |
| Single centre | 40 (65.6) |
| Multicentre | 21 (34.4) |
| Mentioned CONSORT/STROBE adherence in article | 10 (15.4) |
| Funding | |
| No influence of funding on results | 43 (68.3) |
| Possible influence of funding on results | 20 (31.7) |
Missing values were excluded from analysis.
CONSORT, Consolidated Standards of Reporting Trials; RCT, randomised controlled trial; STROBE, Strengthening the Reporting of Observational Studies in Epidemiology.