Placebo-adjusted effect: difference between revisions
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| Revision 9 — 13:20, 29 Jan 2025 ForestPlotFinn (talk) expand §Where the adjustment is not enough 2,887 bytes +34 | Revision 10 — 13:20, 16 Feb 2025 ITT_Imelda (talk) fix a broken wikilink 3,671 bytes +784 | ||
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| 20 | The placebo response proper — improvement attributable to expectation — is only one of these, and in objective endpoints such as body weight it is generally small relative to the others.{{r|hrobjartsson2010}} | 20 | The placebo response proper — improvement attributable to expectation — is only one of these, and in objective endpoints such as body weight it is generally small relative to the others.{{r|hrobjartsson2010}} |
| 21 | 21 | ||
| + | 22 | == How figures are misreported == | |
| + | 23 | | Reported as | Actually | Effect on the impression | | |
| + | 24 | |---|---|---| | |
| + | 25 | | "Lost 15% of body weight" | Active-arm change | Overstates the drug effect | | |
| + | 26 | | "12 percentage points more than placebo" | Placebo-adjusted | Correct | | |
| + | 27 | | "Six times the placebo effect" | Ratio of arms | Sensitive to a small denominator | | |
| + | 28 | | "Up to 24%" | Highest dose, best case | Not the trial's headline result | | |
| + | 29 | ||
| + | 30 | The third row deserves attention: a ratio between arms is unstable when the placebo change is near zero, and a trial with a placebo change of −0.5% will produce a spectacular ratio from an unremarkable difference.{{r|ich_e9}} | |
| + | 31 | ||
| 22 | == References == | 32 | == References == |
| 23 | {{reflist}} | 33 | {{reflist}} |
| ⋮ | ⋮ | ||
| 26 | <ref name="wilding2021">Wilding JPH, Batterham RL, Calanna S, et al. "Once-weekly semaglutide in adults with overweight or obesity." ''New England Journal of Medicine'' 384(11):989–1002 (2021). PMID 33567185.</ref> | 36 | <ref name="wilding2021">Wilding JPH, Batterham RL, Calanna S, et al. "Once-weekly semaglutide in adults with overweight or obesity." ''New England Journal of Medicine'' 384(11):989–1002 (2021). PMID 33567185.</ref> |
| 27 | <ref name="ich_e10">International Council for Harmonisation, ''E10: Choice of Control Group and Related Issues in Clinical Trials'' (2000).</ref> | 37 | <ref name="ich_e10">International Council for Harmonisation, ''E10: Choice of Control Group and Related Issues in Clinical Trials'' (2000).</ref> |
| + | 38 | ||
| + | 39 | == See also == | |
| + | 40 | * [[Intention-to-treat analysis]] | |
| + | 41 | * [[Number needed to treat]] | |
| + | 42 | * [[STEP trial programme]] | |
| + | 43 | * [[SURMOUNT trial programme]] | |
| 28 | 44 | ||
| 29 | {{DEFAULTSORT:Placebo-adjusted effect}} | 45 | {{DEFAULTSORT:Placebo-adjusted effect}} |