Citation networks of related trials are often disconnected: Implications for bidirectional citation searches

Karen A. Robinson, Adam G. Dunn, Guy Tsafnat, Paul Glasziou

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)

Abstract

Background and Objectives Reports of randomized controlled trials (RCTs) should set findings within the context of previous research. The resulting network of citations would also provide an alternative search method for clinicians, researchers, and systematic reviewers seeking to base decisions on all available evidence. We sought to determine the connectedness of citation networks of RCTs by examining direct (referenced trials) and indirect (through references of referenced trials, etc) citation of trials to one another. Methods Meta-analyses were used to create citation networks of RCTs addressing the same clinical questions. The primary measure was the proportion of networks where following citation links between RCTs identifies the complete set of RCTs, forming a single connected citation group. Other measures included the number of disconnected groups (islands) within each network, the number of citations in the network relative to the maximum possible, and the maximum number of links in the path between two connected trials (a measure of indirectness of citations). Results We included 259 meta-analyses with a total of 2,413 and a median of seven RCTs each. For 46% (118 of 259) of networks, the RCTs formed a single connected citation group - one island. For the other 54% of networks, where at least one RCT group was not cited by others, 39% had two citation islands and 4% (10 of 257) had 10 or more islands. On average, the citation networks had 38% of the possible citations to other trials (if each trial had cited all earlier trials). The number of citation islands and the maximum number of citation links increased with increasing numbers of trials in the network. Conclusion Available evidence to answer a clinical question may be identified by using network citations created with a small initial corpus of eligible trials. However, the number of islands means that citation networks cannot be relied on for evidence retrieval.

Original languageEnglish
Pages (from-to)793-799
Number of pages7
JournalJournal of Clinical Epidemiology
Volume67
Issue number7
DOIs
Publication statusPublished - 2014

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title = "Citation networks of related trials are often disconnected: Implications for bidirectional citation searches",
abstract = "Background and Objectives Reports of randomized controlled trials (RCTs) should set findings within the context of previous research. The resulting network of citations would also provide an alternative search method for clinicians, researchers, and systematic reviewers seeking to base decisions on all available evidence. We sought to determine the connectedness of citation networks of RCTs by examining direct (referenced trials) and indirect (through references of referenced trials, etc) citation of trials to one another. Methods Meta-analyses were used to create citation networks of RCTs addressing the same clinical questions. The primary measure was the proportion of networks where following citation links between RCTs identifies the complete set of RCTs, forming a single connected citation group. Other measures included the number of disconnected groups (islands) within each network, the number of citations in the network relative to the maximum possible, and the maximum number of links in the path between two connected trials (a measure of indirectness of citations). Results We included 259 meta-analyses with a total of 2,413 and a median of seven RCTs each. For 46{\%} (118 of 259) of networks, the RCTs formed a single connected citation group - one island. For the other 54{\%} of networks, where at least one RCT group was not cited by others, 39{\%} had two citation islands and 4{\%} (10 of 257) had 10 or more islands. On average, the citation networks had 38{\%} of the possible citations to other trials (if each trial had cited all earlier trials). The number of citation islands and the maximum number of citation links increased with increasing numbers of trials in the network. Conclusion Available evidence to answer a clinical question may be identified by using network citations created with a small initial corpus of eligible trials. However, the number of islands means that citation networks cannot be relied on for evidence retrieval.",
author = "Robinson, {Karen A.} and Dunn, {Adam G.} and Guy Tsafnat and Paul Glasziou",
year = "2014",
doi = "10.1016/j.jclinepi.2013.11.015",
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volume = "67",
pages = "793--799",
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Citation networks of related trials are often disconnected : Implications for bidirectional citation searches. / Robinson, Karen A.; Dunn, Adam G.; Tsafnat, Guy; Glasziou, Paul.

In: Journal of Clinical Epidemiology, Vol. 67, No. 7, 2014, p. 793-799.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Citation networks of related trials are often disconnected

T2 - Implications for bidirectional citation searches

AU - Robinson, Karen A.

AU - Dunn, Adam G.

AU - Tsafnat, Guy

AU - Glasziou, Paul

PY - 2014

Y1 - 2014

N2 - Background and Objectives Reports of randomized controlled trials (RCTs) should set findings within the context of previous research. The resulting network of citations would also provide an alternative search method for clinicians, researchers, and systematic reviewers seeking to base decisions on all available evidence. We sought to determine the connectedness of citation networks of RCTs by examining direct (referenced trials) and indirect (through references of referenced trials, etc) citation of trials to one another. Methods Meta-analyses were used to create citation networks of RCTs addressing the same clinical questions. The primary measure was the proportion of networks where following citation links between RCTs identifies the complete set of RCTs, forming a single connected citation group. Other measures included the number of disconnected groups (islands) within each network, the number of citations in the network relative to the maximum possible, and the maximum number of links in the path between two connected trials (a measure of indirectness of citations). Results We included 259 meta-analyses with a total of 2,413 and a median of seven RCTs each. For 46% (118 of 259) of networks, the RCTs formed a single connected citation group - one island. For the other 54% of networks, where at least one RCT group was not cited by others, 39% had two citation islands and 4% (10 of 257) had 10 or more islands. On average, the citation networks had 38% of the possible citations to other trials (if each trial had cited all earlier trials). The number of citation islands and the maximum number of citation links increased with increasing numbers of trials in the network. Conclusion Available evidence to answer a clinical question may be identified by using network citations created with a small initial corpus of eligible trials. However, the number of islands means that citation networks cannot be relied on for evidence retrieval.

AB - Background and Objectives Reports of randomized controlled trials (RCTs) should set findings within the context of previous research. The resulting network of citations would also provide an alternative search method for clinicians, researchers, and systematic reviewers seeking to base decisions on all available evidence. We sought to determine the connectedness of citation networks of RCTs by examining direct (referenced trials) and indirect (through references of referenced trials, etc) citation of trials to one another. Methods Meta-analyses were used to create citation networks of RCTs addressing the same clinical questions. The primary measure was the proportion of networks where following citation links between RCTs identifies the complete set of RCTs, forming a single connected citation group. Other measures included the number of disconnected groups (islands) within each network, the number of citations in the network relative to the maximum possible, and the maximum number of links in the path between two connected trials (a measure of indirectness of citations). Results We included 259 meta-analyses with a total of 2,413 and a median of seven RCTs each. For 46% (118 of 259) of networks, the RCTs formed a single connected citation group - one island. For the other 54% of networks, where at least one RCT group was not cited by others, 39% had two citation islands and 4% (10 of 257) had 10 or more islands. On average, the citation networks had 38% of the possible citations to other trials (if each trial had cited all earlier trials). The number of citation islands and the maximum number of citation links increased with increasing numbers of trials in the network. Conclusion Available evidence to answer a clinical question may be identified by using network citations created with a small initial corpus of eligible trials. However, the number of islands means that citation networks cannot be relied on for evidence retrieval.

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U2 - 10.1016/j.jclinepi.2013.11.015

DO - 10.1016/j.jclinepi.2013.11.015

M3 - Article

VL - 67

SP - 793

EP - 799

JO - Journal of Chronic Diseases

JF - Journal of Chronic Diseases

SN - 0895-4356

IS - 7

ER -