ArticleBMC medical research methodology2002
Meta-analysis, Simpson's paradox, and the number needed to treat.
Article in BMC medical research methodology, 2002. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 52 papers, 27 of them syntheses that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Who cites it
52 citing papers in PubMed, 27 syntheses or guidelines pooled it.
- Cardiovascular and Renal Benefits of Novel Diabetes Drugs by Baseline Cardiovascular Risk: A Systematic Review, Meta-analysis, and Meta-regression.Diabetes care · 2023Pooled it
- Performance of several types of beta-binomial models in comparison to standard approaches for meta-analyses with very few studies.BMC medical research methodology · 2022Pooled it
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- Botulinum toxin type A versus anticholinergics for cervical dystonia.The Cochrane database of systematic reviews · 2021Pooled it
- Botulinum toxin type A therapy for blepharospasm.The Cochrane database of systematic reviews · 2020Pooled it
- Botulinum toxin type A therapy for hemifacial spasm.The Cochrane database of systematic reviews · 2020Pooled it
- Botulinum toxin type A therapy for cervical dystonia.The Cochrane database of systematic reviews · 2020Pooled it
- Deep brain stimulation for dystonia.The Cochrane database of systematic reviews · 2019Pooled it
- Percutaneous closure versus medical therapy for stroke with patent foramen Ovale: a systematic review and meta-analysis.BMC cardiovascular disorders · 2018Pooled it
- Systemic treatments for metastatic cutaneous melanoma.The Cochrane database of systematic reviews · 2018Pooled it
- Botulinum toxin type A therapy for cervical dystonia.The Cochrane database of systematic reviews · 2017Pooled it
- Botulinum toxin type A versus botulinum toxin type B for cervical dystonia.The Cochrane database of systematic reviews · 2016Pooled it
- Pooled it
- Sequential versus standard triple first-line therapy for Helicobacter pylori eradication.The Cochrane database of systematic reviews · 2016Pooled it
- Botulinum toxin type B for cervical dystonia.The Cochrane database of systematic reviews · 2016Pooled it
- Bias and precision of methods for estimating the difference in restricted mean survival time from an individual patient data meta-analysis.BMC medical research methodology · 2016Pooled it
- Pooled it
- Statins and Cardiovascular Primary Prevention in CKD: A Meta-Analysis.Clinical journal of the American Society of Nephrology : CJASN · 2015 · on this mapPooled it
- Intermittent versus continuous androgen deprivation for locally advanced, recurrent or metastatic prostate cancer: a systematic review and meta-analysis.BMC urology · 2014Pooled it
- Optimum duration of regimens for Helicobacter pylori eradication.The Cochrane database of systematic reviews · 2013Pooled it
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2 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThere is debate concerning methods for calculating numbers needed to treat (NNT) from results of systematic reviews.
methodsWe investigate the susceptibility to bias for alternative methods for calculating NNTs through illustrative examples and mathematical theory.
resultsTwo competing methods have been recommended: one method involves calculating the NNT from meta-analytical estimates, the other by treating the data as if it all arose from a single trial. The 'treat-as-one-trial' method was found to be susceptible to bias when there were imbalances between groups within one or more trials in the meta-analysis (Simpson's paradox). Calculation of NNTs from meta-analytical estimates is not prone to the same bias. The method of calculating the NNT from a meta-analysis depends on the treatment effect used. When relative measures of treatment effect are used the estimates of NNTs can be tailored to the level of baseline risk.
conclusionsThe treat-as-one-trial method of calculating numbers needed to treat should not be used as it is prone to bias. Analysts should always report the method they use to compute estimates to enable readers to judge whether it is appropriate.
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