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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 %)