Evidence map›Paper›PMID 16505459›Full record

ArticleCMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne2006

Comparison of evidence on harms of medical interventions in randomized and nonrandomized studies.

Panagiotis N Papanikolaou, Georgia D Christidi, John P A Ioannidis

Abstract readComparative Study
PubMed Full text at PMC Publisher
In one paragraph

Article in CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 2006. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 66 papers, 20 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
66citing papers in PubMed, 20 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

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.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

66 citing papers in PubMed, 20 syntheses or guidelines pooled it.

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  5. Potential increased risk of cancer from commonly used medications: an umbrella review of meta-analyses.Annals of oncology : official journal of the European Society for Medical Oncology · 2014
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  13. Randomisation to protect against selection bias in healthcare trials.The Cochrane database of systematic reviews · 2011
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6 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

5 · Who and what money

Authors and funding

3 authors.

Panagiotis N PapanikolaouClinical Trials and Evidence-Based Medicine Unit, Department of Hygiene and Epidemiology, University of Ioannina School of Medicine, Ioannina, Greece.
Georgia D Christidi
John P A Ioannidis

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundInformation on major harms of medical interventions comes primarily from epidemiologic studies performed after licensing and marketing. Comparison with data from large-scale randomized trials is occasionally feasible. We compared evidence from randomized trials with that from epidemiologic studies to determine whether they give different estimates of risk for important harms of medical interventions.

methodsWe targeted well-defined, specific harms of various medical interventions for which data were already available from large-scale randomized trials (> 4000 subjects). Nonrandomized studies involving at least 4000 subjects addressing these same harms were retrieved through a search of MEDLINE. We compared the relative risks and absolute risk differences for specific harms in the randomized and nonrandomized studies.

resultsEligible nonrandomized studies were found for 15 harms for which data were available from randomized trials addressing the same harms. Comparisons of relative risks between the study types were feasible for 13 of the 15 topics, and of absolute risk differences for 8 topics. The estimated increase in relative risk differed more than 2-fold between the randomized and nonrandomized studies for 7 (54%) of the 13 topics; the estimated increase in absolute risk differed more than 2-fold for 5 (62%) of the 8 topics. There was no clear predilection for randomized or nonrandomized studies to estimate greater relative risks, but usually (75% [6/8]) the randomized trials estimated larger absolute excess risks of harm than the nonrandomized studies did.

interpretationNonrandomized studies are often conservative in estimating absolute risks of harms. It would be useful to compare and scrutinize the evidence on harms obtained from both randomized and nonrandomized studies.

Indexed as

Epidemiologic StudiesBiasDrug-Related Side Effects and Adverse ReactionsEvidence-Based MedicineHumansRandomized Controlled Trials as TopicRiskSurgical Procedures, OperativeVaccinesVitaminsVaccinesVitamins

Identifiers

PMID16505459
PMCPMC1389826

What OpenQuestion holds

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.