| Ref ID | 521 |
| First Author | P. R. M. Smith |
| Journal | BMJ EVIDENCE-BASED MEDICINE |
| Year Of Publishing | 2020 |
| URL | https://ebm.bmj.com/content/early/2020/03/10/bmjebm-2019-111257 |
| Keywords |
• Inference • General medical • Cochrane • Author |
| Problem(s) |
• Incorrect interpretation or statistical inference error from meta-analysis |
| Article Type | Empirical |
| Article Subtype | Cross-sectional survey/Methodological systematic review |
| First Author Country | United Kingdom |
| Aim | To assess abstracts of 460 Cochrane and 218 non-Cochrane systematic reviews published in 2017 to identify unqualified claims of ‘no difference’ or ‘no effect’ of treatments. The inference is incorrect because ‘absence of evidence is not evidence of absence’. |
| Level of Investigation | Descriptive |
| Summary of Findings | 'No difference/no effect' was incorrectly claimed in the abstracts of 7.8% Cochrane reviews and in the abstracts of 6.0% other systematic reviews. Incorrect claims of no difference/no effect of treatments were substantially less common in Cochrane reviews published in in 2017 than they were in a study of abstracts of reviews published in 2001/2002 (Alderson P, Chalmers I. Survey of claims of no effect in Abstracts of Cochrane reviews. BMJ 2003;326:475–6). |
| Number of systematic reviews included | 678 |
| Number of eligible systematic reviews assessed | 1286 |
| Treatment impacted | No |
| Treatment impacted description | |
| Interpretation impacted | Yes |
| Interpretation impacted description | The authors highlight that "Leaving readers with the impression that there is no difference between alternative treatments may result in dangerously misinformed clinical decisions and failure to address important uncertainties in additional research." |