Evidence map›Paper›PMID 10861325›Full record

ArticleThe New England journal of medicine2000

Randomized, controlled trials, observational studies, and the hierarchy of research designs.

J Concato, N Shah, R I Horwitz

Registry-linked trialOpen access · bronzeAbstract readComparative Study
PubMed Full text at PMC Publisher
In one paragraph

Article in The New England journal of medicine, 2000. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT03250754 (Treatment of Headache Disorders With Acupuncture), which is not on this map. Cited by 866 papers, 32 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
866citing papers in PubMed, 32 pooled it
255.1field-weighted citation impact, top 1% of its field
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.

NCT03250754 completednot on this mapstarted 2017, after this paper: background citation

Treatment of Headache Disorders With Acupuncture: Observational Study (HDACU)

TypeobservationalSponsorHospital Son LlatzerRan2017 to 2018Enrolled482ConditionsChronic Headache DisorderArmsElectroacupuncture
3 · Its place in the literature

Who cites it

866 citing papers in PubMed, 32 syntheses or guidelines pooled it, 3,513 citations in OpenAlex.

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  5. The Added Value and the Efficacy of Preoperative Physiotherapy on Degenerative Diseases of the Lumbar Spine: A Systematic Review.Physiotherapy research international : the journal for researchers and clinicians in physical therapy · 2026
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806 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 at 1 institution in 1 country.

J ConcatoDepartment of Internal Medicine, Yale University School of Medicine, New Haven, Conn 06510, USA. john.concato@yale.edu
N Shah
R I Horwitz
Yale University · US

Funding

Methodologic quality predictors of observational studiesF32HL074478 · NHLBI · NEW YORK UNIVERSITY SCHOOL OF MEDICINE · PI SHAH, NIRAV RAMESH · 2003 to 2003
$52k
NHLBI NIH HHS F32 HL074478
6 · The paper itself

Abstract

backgroundIn the hierarchy of research designs, the results of randomized, controlled trials are considered to be evidence of the highest grade, whereas observational studies are viewed as having less validity because they reportedly overestimate treatment effects. We used published meta-analyses to identify randomized clinical trials and observational studies that examined the same clinical topics. We then compared the results of the original reports according to the type of research design.

methodsA search of the Medline data base for articles published in five major medical journals from 1991 to 1995 identified meta-analyses of randomized, controlled trials and meta-analyses of either cohort or case-control studies that assessed the same intervention. For each of five topics, summary estimates and 95 percent confidence intervals were calculated on the basis of data from the individual randomized, controlled trials and the individual observational studies.

resultsFor the five clinical topics and 99 reports evaluated, the average results of the observational studies were remarkably similar to those of the randomized, controlled trials. For example, analysis of 13 randomized, controlled trials of the effectiveness of bacille Calmette-Guérin vaccine in preventing active tuberculosis yielded a relative risk of 0.49 (95 percent confidence interval, 0.34 to 0.70) among vaccinated patients, as compared with an odds ratio of 0.50 (95 percent confidence interval, 0.39 to 0.65) from 10 case-control studies. In addition, the range of the point estimates for the effect of vaccination was wider for the randomized, controlled trials (0.20 to 1.56) than for the observational studies (0.17 to 0.84).

conclusionsThe results of well-designed observational studies (with either a cohort or a case-control design) do not systematically overestimate the magnitude of the effects of treatment as compared with those in randomized, controlled trials on the same topic.

Indexed as

Case-Control StudiesCohort StudiesRandomized Controlled Trials as TopicResearch DesignTherapeuticsAnticholesteremic AgentsBCG VaccineBreast NeoplasmsFemaleHumansHypertensionMammographyMeta-Analysis as TopicTreatment OutcomeAnticholesteremic AgentsBCG Vaccine

Identifiers

PMID10861325
PMCPMC1557642
OpenAlexW2319983832

What OpenQuestion holds

Textmetadata
Read underepoch 390

Registered trials

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.