Comparison of statistical and magnitude of effect discrepancies between randomized controlled trial and nonrandomized study results
| Discrepancy definition | All outcomes, n = 10 | Topic/outcome comparison no. |
|---|---|---|
| Visual assessment of directionality of effect | ||
| nRCTs overestimate treatment effect | 3 | 2, 3, 6 |
| nRCTs underestimate treatment effect | 1 | 8 |
| Agreement | 6 | 1, 4, 5, 7, 9, 10 |
| Magnitude of effect, ≥ 2-fold difference in RR | 2 | 2, 3 |
| Disagreement of statistical significance | 3 | 3, 5, 6 |
| z score, absolute value > 1.96 | 0 | NA |
NA = not applicable; nRCTs = nonrandomized study; RR = relative risk.