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Table 1 Rationale or reference provided for the mean difference (MD) estimate used in power calculation in 264 RCTs

From: Estimates of the mean difference in orthopaedic randomized trials: obligatory yet obscure

Rationale or reference provided for the estimate of the mean difference in power calculation

Number of RCTs (%)

No rationale or reference

156 (59 %)

Provided some rationale or reference

108 (41 %)

Rationale or reference provided by PROM and non-PROM RCTs

 RCTs with PROM primary outcome

69/148 (47 %)

 RCTs with non-PROM primary outcome

39/116 (34 %)

The rationale or reference provided in power calculation

  MCID or MDC or PASS from psychometric study for PROM

43 (16 %)

 Validation study of the PROM

3 (1 %)

 Standardized effect size

2 (1 %)

 Systematic review of subject

1 (0.4 %)

 RCTs

11 (4 %)

 Observational studies

23 (9 %)

 Pilot study or pilot data

5 (2 %)

 Case series

1 (0.4 %)

 ‘Clinical relevance’, ‘Clinical judgement’, ‘Clinical experience’

15 (6 %)

 Proportional difference to the mean value of historical cohort or MCID (27–40 % decrease)

4 (2 %)