Evidence map›Paper›PMID 32046643›Full record

ArticleBMC medical research methodology2020

Outcome choice and definition in systematic reviews leads to few eligible studies included in meta-analyses: a case study.

Ian J Saldanha, Kristina B Lindsley, Sarah Money, Hannah J Kimmel, Bryant T Smith, Kay Dickersin

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In one paragraph

Article in BMC medical research methodology, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 21 papers, 5 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
21citing papers in PubMed, 5 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

21 citing papers in PubMed, 5 syntheses or guidelines pooled it.

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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

6 authors.

Ian J SaldanhaCenter for Evidence Synthesis in Health, Department of Health Services, Policy, and Practice (Primary), Department of Epidemiology (Secondary), Brown University School of Public Health, 121 South Main Street, Box G-S121-8, Providence, RI, 02903, USA. ian_saldanha@brown.edu.ORCID 0000-0002-2062-3382
Kristina B LindsleyJulius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Room Str. 6.127, Utrecht, GA, 3508, Netherlands.
Sarah MoneyISA Group, 201 North Union Street, Suite 300, Alexandria, VA, 22314, USA.
Hannah J KimmelCenter for Evidence Synthesis in Health, Department of Health Services, Policy, and Practice, Brown University School of Public Health, 121 South Main Street, Box G-S121-8, Providence, RI, 02903, USA.
Bryant T SmithCenter for Evidence Synthesis in Health, Department of Health Services, Policy, and Practice, Brown University School of Public Health, 121 South Main Street, Box G-S121-8, Providence, RI, 02903, USA.
Kay DickersinDepartment of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD, 21205, USA.

Funding

Maximizing Use of High-Quality Evidence in Eye Care: Cochrane Eyes and Vision US ProjectUG1EY020522 · NEI · UNIVERSITY OF COLORADO DENVER · PI Tianjing Li · 2017 to 2026
$10.1M
NEI NIH HHS UG1 EY020522
6 · The paper itself

Abstract

backgroundThere is broad recognition of the importance of evidence in informing clinical decisions. When information from all studies included in a systematic review ("review") does not contribute to a meta-analysis, decision-makers can be frustrated. Our objectives were to use the field of eyes and vision as a case study and examine the extent to which authors of Cochrane reviews conducted meta-analyses for their review's pre-specified main outcome domain and the reasons that some otherwise eligible studies were not incorporated into meta-analyses.

methodsWe examined all completed systematic reviews published by Cochrane Eyes and Vision, as of August 11, 2017. We extracted information about each review's outcomes and, using an algorithm, categorized one outcome as its "main" outcome. We calculated the percentage of included studies incorporated into meta-analyses for any outcome and for the main outcome. We examined reasons for non-inclusion of studies into the meta-analysis for the main outcome.

resultsWe identified 175 completed reviews, of which 125 reviews included two or more studies. Across these 125 reviews, the median proportions of studies incorporated into at least one meta-analysis for any outcome and for the main outcome were 74% (interquartile range [IQR] 0-100%) and 28% (IQR 0-71%), respectively. Fifty-one reviews (41%) could not conduct a meta-analysis for the main outcome, mostly because fewer than two included studies measured the outcome (21/51 reviews) or the specific measurements for the outcome were inconsistent (16/51 reviews).

conclusionsOutcome choice during systematic reviews can lead to few eligible studies included in meta-analyses. Core outcome sets and improved reporting of outcomes can help solve some of these problems.

Indexed as

Evidence-Based MedicineHealth ServicesHumansMeta-Analysis as TopicOutcome Assessment, Health CareReproducibility of ResultsSystematic Reviews as TopicClinical trialsCore outcome setsLoss of informationMeta-analysisOutcomesSystematic review

Identifiers

PMID32046643
PMCPMC7014938

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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.