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Table 1 Comparison of non-truncated RCTs only and truncated + non-truncated RCTs as comparators to estimate the magnitude of bias associated with stopping clinical trials early for benefit based on simulations and theoretical considerations.

From: Stopping randomized trials early for benefit: a protocol of the Study Of Trial Policy Of Interim Truncation-2 (STOPIT-2)

Non-truncated RCTs only Truncated & non-truncated RCTs
- more appropriate when the number of non-truncated RCTs in meta-analyses is relatively small (= weight of tRCTs in meta-analyses relatively large) - more appropriate when the number of non-truncated RCTs in meta-analyses is relatively large (= weight of tRCTs in meta-analyses relatively small)
- more appropriate when true treatment effects are small (RCTs in meta-analyses likely to be underpowered) - more appropriate when true treatment effects are large (RCTs in meta-analyses likely to be adequately powered)
- more appropriate in the presence of considerable publication bias - more conservative bias estimation
- more appropriate when proportion of trials in meta-analyses without formal stopping rule is large  
- trial sample separate/independent from tRCT(s) facilitates statistical analysis  
  1. Abbreviations: RCTs, randomized clinical trials; tRCT(s), truncated randomized clinical trial(s) due to stopping early for benefit