Reporting of Conflicts of Interest in Cochrane Reviews
Reporting of Conflicts of Interest in Cochrane Reviews
We searched the Cochrane Database of Systematic Reviews through the Cochrane Library on 28 March 2011, using the MeSH term “drug therapy,” to identify Cochrane reviews of drug interventions published in 2010. Cochrane reviews are published in the Cochrane Database of Systematic Reviews when new and when updates (that is, a new search) or amendments (that is, edited to make corrections or to reflect changes in methodology) are made to previously published reviews. Because reporting standards are evolving, we restricted the search to this one year period to obtain recent systematic reviews, with or without meta-analyses, that reflected relatively current reporting practices.
Cochrane reviews published in 2010 were eligible if they included a documented systematic review of the literature classified by Cochrane as up to date in 2008 or later, included results from at least one randomised controlled trial, and evaluated the efficacy, effectiveness, or harm of a drug or class of drug against an alternative treatment (for example, placebo, alternative drug). We excluded reviews that only assessed different methods for administering a drug or dosage schedules of that drug. Drugs were defined broadly to include biologicals and vaccines but not nutritional supplements (for example, vitamins) or medical devices without a drug component. We included reviews that investigated a combination of drug and non-drug interventions (for example, psychotherapy), or interventions that may or may not involve a drug (for example, amnioinfusion), if a study group was exclusively given a drug intervention or if the review assessed the addition of a drug to a treatment received by both intervention and control groups. Interventions were classified as having a drug component if any form of the active ingredient (for example, dosage, route, strength, compound) was listed as an approved or discontinued brand name, generic drug, or therapeutic biological product by the US Food and Drug Administration. For agents not listed in the Drugs@FDA database, we determined drug status on the basis of consensus among investigators, using publically available sources that provided information on a particular agent.
Two investigators independently reviewed Cochrane reviews for eligibility. If either reviewer deemed a review to be potentially eligible based on review of the title and abstract, then we carried out a review of the full text. Two reviewers also independently carried out full text reviews, with any disagreements resolved by consensus. Cohen’s κ statistic was used to assess agreement between reviewers corrected by chance.
Two investigators independently extracted and entered into a standardised spreadsheet data items from the Cochrane reviews, with any discrepancies resolved by consensus. Investigators reviewed all text, tables, figures, appendices, disclosure statements, and acknowledgments from each Cochrane review to record disclosed conflicts of interest from each selected Cochrane review (review funding source and review author-industry financial ties). They also determined whether or not conflicts of interest from included trials (trial funding sources, trial author-industry financial ties, or trial author-industry employment) were reported in the reviews. Data items were extracted only from the included Cochrane reviews and not from any additional sources, such as online Cochrane resources (see Supplementary Appendix 1 for data extraction forms).
We extracted the funding sources for the Cochrane reviews from the sources of support declaration or acknowledgments and classified them as non-industry (for example, public granting agency, private not for profit granting agency), combined pharmaceutical industry and non-industry, or none reported (review not funded or review funding information not disclosed). Financial ties of review authors to industry were defined per the July 2010 version of the International Committee of Medical Journal Editors uniform disclosure form for potential conflicts of interest and included current or former board membership, current or former consultancy work, current or former industry employment, expert testimony, industry grants (issued or pending), payment for lectures including service on speakers bureaus, payment for manuscript preparation, patents (planned, pending, or issued), royalties, payment for development of educational presentations, stock or stock options, travel reimbursement, or other relations with industry, as disclosed in the review. If a review did not contain a disclosure statement, we coded review author-industry financial ties as not reported.
For each Cochrane review we also recorded whether the review reported information on the following types of conflicts of interest from included trials: trial funding sources, trial author-industry financial ties, and trial author-industry employment. For each of these types of conflicts of interest from included trials, we coded the reviews as reporting fully (reporting for all included trials), partially (reporting for some, but not all, included trials), or not reporting. We coded reviews as not reporting trial funding sources if they included data from pharmaceutical industry databases or noted that trial drugs were supplied by the manufacturers for certain trials but did not make any explicit statement of trial funding sources. For Cochrane reviews that reported information on conflicts of interest from included trials either fully or partially, we recorded where the information was reported. Specifically, we recorded whether the information was reported in the context of the risk of bias assessment (text, figure, or risk of bias table attached to the table showing the characteristics of the included studies) or outside of the context of the risk of bias assessment, including the text, the characteristics of included studies table, other table, the abstract, the plain language summary, in a footnote of a summary of findings table, or in the context of sensitivity analyses. In addition to coding whether conflicts of interest from included trials were reported in the Cochrane reviews, we coded whether the review’s reported data extraction protocol included extracting data on trial funding sources and trial author-industry financial ties or employment (yes, no, could not be determined).
A protocol was not published or registered for the present study. However, all methods were determined a priori with two exceptions. Firstly, during data extraction we added the classification of Cochrane reviews as funded by “combined industry and non-industry” sources. This was because, although the Cochrane Handbook states that commercial funding of reviews is prohibited, we encountered three Cochrane reviews where industry funding sources, along with non-industry funding sources, were listed. Secondly, our initial review protocol indicated that Cochrane reviews would be coded as either reporting or not reporting conflicts of interest information from included trials. We added the fully and partially reporting classifications because some reviews provided information on some, but not all, included trials. This occurred, for instance, when reviews mentioned a subset of included trials as funded by industry but did not provide information on the funding status of other trials (non-industry funding, no trial funding, not reported).
Methods
Selection of Systematic Reviews
We searched the Cochrane Database of Systematic Reviews through the Cochrane Library on 28 March 2011, using the MeSH term “drug therapy,” to identify Cochrane reviews of drug interventions published in 2010. Cochrane reviews are published in the Cochrane Database of Systematic Reviews when new and when updates (that is, a new search) or amendments (that is, edited to make corrections or to reflect changes in methodology) are made to previously published reviews. Because reporting standards are evolving, we restricted the search to this one year period to obtain recent systematic reviews, with or without meta-analyses, that reflected relatively current reporting practices.
Eligibility Criteria
Cochrane reviews published in 2010 were eligible if they included a documented systematic review of the literature classified by Cochrane as up to date in 2008 or later, included results from at least one randomised controlled trial, and evaluated the efficacy, effectiveness, or harm of a drug or class of drug against an alternative treatment (for example, placebo, alternative drug). We excluded reviews that only assessed different methods for administering a drug or dosage schedules of that drug. Drugs were defined broadly to include biologicals and vaccines but not nutritional supplements (for example, vitamins) or medical devices without a drug component. We included reviews that investigated a combination of drug and non-drug interventions (for example, psychotherapy), or interventions that may or may not involve a drug (for example, amnioinfusion), if a study group was exclusively given a drug intervention or if the review assessed the addition of a drug to a treatment received by both intervention and control groups. Interventions were classified as having a drug component if any form of the active ingredient (for example, dosage, route, strength, compound) was listed as an approved or discontinued brand name, generic drug, or therapeutic biological product by the US Food and Drug Administration. For agents not listed in the Drugs@FDA database, we determined drug status on the basis of consensus among investigators, using publically available sources that provided information on a particular agent.
Two investigators independently reviewed Cochrane reviews for eligibility. If either reviewer deemed a review to be potentially eligible based on review of the title and abstract, then we carried out a review of the full text. Two reviewers also independently carried out full text reviews, with any disagreements resolved by consensus. Cohen’s κ statistic was used to assess agreement between reviewers corrected by chance.
Data Extraction
Two investigators independently extracted and entered into a standardised spreadsheet data items from the Cochrane reviews, with any discrepancies resolved by consensus. Investigators reviewed all text, tables, figures, appendices, disclosure statements, and acknowledgments from each Cochrane review to record disclosed conflicts of interest from each selected Cochrane review (review funding source and review author-industry financial ties). They also determined whether or not conflicts of interest from included trials (trial funding sources, trial author-industry financial ties, or trial author-industry employment) were reported in the reviews. Data items were extracted only from the included Cochrane reviews and not from any additional sources, such as online Cochrane resources (see Supplementary Appendix 1 for data extraction forms).
We extracted the funding sources for the Cochrane reviews from the sources of support declaration or acknowledgments and classified them as non-industry (for example, public granting agency, private not for profit granting agency), combined pharmaceutical industry and non-industry, or none reported (review not funded or review funding information not disclosed). Financial ties of review authors to industry were defined per the July 2010 version of the International Committee of Medical Journal Editors uniform disclosure form for potential conflicts of interest and included current or former board membership, current or former consultancy work, current or former industry employment, expert testimony, industry grants (issued or pending), payment for lectures including service on speakers bureaus, payment for manuscript preparation, patents (planned, pending, or issued), royalties, payment for development of educational presentations, stock or stock options, travel reimbursement, or other relations with industry, as disclosed in the review. If a review did not contain a disclosure statement, we coded review author-industry financial ties as not reported.
For each Cochrane review we also recorded whether the review reported information on the following types of conflicts of interest from included trials: trial funding sources, trial author-industry financial ties, and trial author-industry employment. For each of these types of conflicts of interest from included trials, we coded the reviews as reporting fully (reporting for all included trials), partially (reporting for some, but not all, included trials), or not reporting. We coded reviews as not reporting trial funding sources if they included data from pharmaceutical industry databases or noted that trial drugs were supplied by the manufacturers for certain trials but did not make any explicit statement of trial funding sources. For Cochrane reviews that reported information on conflicts of interest from included trials either fully or partially, we recorded where the information was reported. Specifically, we recorded whether the information was reported in the context of the risk of bias assessment (text, figure, or risk of bias table attached to the table showing the characteristics of the included studies) or outside of the context of the risk of bias assessment, including the text, the characteristics of included studies table, other table, the abstract, the plain language summary, in a footnote of a summary of findings table, or in the context of sensitivity analyses. In addition to coding whether conflicts of interest from included trials were reported in the Cochrane reviews, we coded whether the review’s reported data extraction protocol included extracting data on trial funding sources and trial author-industry financial ties or employment (yes, no, could not be determined).
A protocol was not published or registered for the present study. However, all methods were determined a priori with two exceptions. Firstly, during data extraction we added the classification of Cochrane reviews as funded by “combined industry and non-industry” sources. This was because, although the Cochrane Handbook states that commercial funding of reviews is prohibited, we encountered three Cochrane reviews where industry funding sources, along with non-industry funding sources, were listed. Secondly, our initial review protocol indicated that Cochrane reviews would be coded as either reporting or not reporting conflicts of interest information from included trials. We added the fully and partially reporting classifications because some reviews provided information on some, but not all, included trials. This occurred, for instance, when reviews mentioned a subset of included trials as funded by industry but did not provide information on the funding status of other trials (non-industry funding, no trial funding, not reported).
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