Conflicts of Interest in Literature Reviews

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-27

Quick Answer

A conflict of interest in a literature review is any financial, intellectual, or personal relationship that could bias how you select, interpret, or report evidence, and it must be disclosed to the journal or publisher.
Identify all funding sources, consulting arrangements, advisory roles, and close personal relationships with authors whose work you are reviewing, then declare them in the conflict-of-interest statement before submission.
Disclosure alone does not eliminate bias, but failing to disclose a relevant conflict can lead to rejection, retraction, or damage to your professional reputation.

What Counts as a Conflict of Interest in a Literature Review

A conflict of interest arises when your judgment about the evidence could be influenced by factors other than the scientific merit of the studies you are reviewing. In a literature review, this matters because the reviewer holds substantial power over which studies are included, how they are weighted, and what conclusions readers draw.

The Committee on Publication Ethics identifies conflicts of interest as a core practice in publication ethics, alongside authorship, peer review, and data integrity. Journals and funding agencies expect authors to declare any competing interests that could reasonably be perceived as affecting their work. The key word is "perceived" because even the appearance of bias can undermine confidence in your review.

Conflicts in literature reviews fall into three broad categories:

Financial conflicts involve money or economic benefit. Examples include receiving research funding from a company whose product is evaluated in the review, holding stock in a pharmaceutical or agricultural company, serving as a paid consultant, or receiving speaking fees from an organization with a stake in the review's conclusions.

Intellectual conflicts involve professional or academic commitments that could bias your judgment. These include having published extensively on one side of a scientific debate, holding a patent related to the topic, serving as an editor for a journal that publishes research in the area, or having a strong prior position in a controversial field.

Personal conflicts involve relationships that could affect objectivity. These include close friendships or family relationships with authors whose work you are reviewing, professional rivalries, or collaborations that might make you either overly favorable or overly critical of particular research groups.

For a literature review specifically, an additional consideration is whether you have a stake in the outcome. If you are reviewing evidence about a feed additive and you hold the patent for that additive, your review of the literature on that topic carries an obvious conflict. Similarly, if you have spent your career arguing that a particular management practice is harmful, your review of evidence on that practice may be unconsciously skewed.

Why Disclosure Matters for Credibility

The credibility of a literature review depends on readers trusting that the author has evaluated evidence fairly. When a conflict is disclosed, readers can weigh the review's conclusions with appropriate caution. When a conflict is hidden and later discovered, the entire review becomes suspect, and the author's other work may be questioned as well.

The Committee on Publication Ethics core practices state that journals should have clear policies on conflicts of interest and that authors should declare all relevant competing interests. These policies exist because undisclosed conflicts have led to retractions, damaged careers, and eroded public trust in scientific literature.

For life-science professionals, the stakes are practical. A farmer who reads a review of antibiotic alternatives needs to know whether the author has financial ties to one of the products being compared. A veterinarian who relies on a systematic review to make treatment decisions needs to know whether the reviewer has a professional stake in one treatment approach. A researcher who cites a review in their grant application needs to know whether the evidence synthesis is trustworthy.

Disclosure also protects you as the author. A clear conflict-of-interest statement demonstrates that you understand the ethical standards of scientific publishing and that you are willing to be transparent about your relationships. This transparency builds trust with editors, reviewers, and readers.

How to Identify Your Own Conflicts

Identifying conflicts requires honest self-assessment. Before you begin writing, and again before you submit, work through the following questions:

Funding and employment questions:

Who paid for the work that led to this review?
Does your employer have a financial interest in the review's outcome?
Have you received grants, gifts, or equipment from any organization with a stake in the topic?

Consulting and advisory questions:

Do you serve on any scientific advisory boards related to the topic?
Have you provided paid consulting to companies whose products appear in the review?
Do you hold any honorary or unpaid positions that could create perceived bias?

Financial interest questions:

Do you or your immediate family hold stock or options in companies relevant to the review?
Do you hold patents or pending patents related to the topic?
Have you received royalties or licensing fees from any relevant product or process?

Intellectual and personal questions:

Have you published extensively on one side of the debate?
Are you currently collaborating with or competing against any authors whose work you are reviewing?
Do you have personal relationships with any authors whose work is included?

The National Institutes of Health requires grant applicants to disclose financial conflicts of interest and to follow institutional policies for managing those conflicts. Even if your review is not funded by NIH, the same principles of transparency apply to any scholarly publication.

At a Glance: Conflict Types and Disclosure Requirements

Conflict Type	Examples in Life-Science Reviews	Disclosure Required	Management Approach
Financial	Research funding from a feed company, stock ownership in a pharmaceutical firm, paid consulting for a vaccine manufacturer	Yes, always	Declare in the conflict-of-interest statement and in the funding section
Intellectual	Prior publications strongly favoring one management approach, serving as journal editor for the field, holding a patent on a reviewed technology	Yes, when it could reasonably affect interpretation	Declare and explain the nature of the intellectual commitment
Personal	Close friendship with a study author, family relationship with a researcher, recent collaboration or rivalry	Yes, when it could affect objectivity	Declare and consider asking a colleague to review your inclusion decisions

How to Disclose Conflicts Properly

Proper disclosure follows the requirements of the target journal and the conventions of scientific publishing. The process involves several distinct steps.

Check the journal's policy first. Most journals have specific instructions for conflict-of-interest statements. These instructions are usually found in the author guidelines or submission requirements. The EQUATOR Network provides access to reporting guidelines that can help you understand what journals expect for transparent research reporting, including disclosure of competing interests.

Use the journal's disclosure form. Many journals require authors to complete a standardized disclosure form, often based on the International Committee of Medical Journal Editors format. Even if the form is not required, completing it can help you identify conflicts you might otherwise overlook.

Write a clear conflict-of-interest statement. The statement should be specific about the nature of the conflict. Instead of writing "I have no conflicts," write "I have received research funding from XYZ Animal Health for studies of feed additives, and I hold stock in that company." This specificity allows readers to understand the exact nature of the relationship.

Include the statement in the manuscript. The conflict-of-interest statement typically appears before the references or in a dedicated section near the end of the manuscript. Some journals also require disclosure in the cover letter.

Update disclosures if circumstances change. If you acquire a new financial interest while your manuscript is under review, you should inform the journal editor immediately. The same applies if you enter into a consulting arrangement or take on a new advisory role.

Use persistent identifiers to maintain accurate records. The ORCID researcher profile system allows you to maintain a record of your affiliations, funding, and publications. Keeping this record current helps demonstrate transparency and makes it easier to identify potential conflicts across your body of work.

Practical Steps for Assessing Conflicts Before Submission

Before you submit your literature review, work through this assessment checklist:

Step 1: Inventory your relationships. List every organization that has paid you, employed you, funded your research, or invited you to serve in an advisory capacity during the past three years. Include current relationships and those that ended recently.

Step 2: Map relationships to the review topic. For each organization on your list, ask whether that organization has any stake in the topic of your review. A company that makes poultry vaccines has a stake in a review of poultry vaccination strategies. A company that makes organic fertilizers may have a stake in a review comparing conventional and organic production systems.

Step 3: Consider indirect relationships. Your spouse's employer, your close collaborator's consulting arrangements, and your department's funding sources can all create perceived conflicts. Consider whether these indirect relationships could reasonably be seen as affecting your judgment.

Step 4: Assess the nature of each conflict. Not all conflicts are equal. A small consulting fee from a company whose product is mentioned in passing is different from substantial equity in a company whose product is the central focus of the review. Be honest about the magnitude of each conflict.

Step 5: Decide on disclosure or management. For most conflicts, disclosure is sufficient. For severe conflicts, you may need to take additional steps, such as having a colleague review your inclusion criteria or excluding certain studies from your analysis. Some journals will not consider reviews from authors with certain types of conflicts.

Step 6: Document your decisions. Keep a record of your conflict assessment, including the date you performed it and the decisions you made. This documentation can be valuable if questions arise later.

Records and Measurements for Conflict Management

Maintaining good records of your conflict assessment is part of responsible research practice. The following records are worth keeping:

Funding records. Maintain a file of all grants, contracts, and gifts that supported your work, including the dates, amounts, and purposes. The National Institutes of Health requires detailed financial conflict-of-interest reporting for funded researchers, and similar records are useful for any scholarly work.

Consulting and advisory records. Keep track of all consulting agreements, advisory board memberships, and honoraria. Include the dates of service and the nature of the relationship.

Publication and collaboration records. Maintain a current curriculum vitae that lists your publications, collaborations, and professional service. This record helps you identify intellectual conflicts and personal relationships that might affect your objectivity.

Disclosure statements. Save copies of every conflict-of-interest statement you have submitted, along with the journal's disclosure requirements for each submission. This record helps you maintain consistency across your publications.

Correspondence with editors. If you disclose a conflict and the editor responds with guidance, save that correspondence. It documents that you followed proper procedures and can be useful if questions arise later.

Common Failure Patterns in Conflict Disclosure

Understanding how conflict disclosure goes wrong can help you avoid the same mistakes. The following patterns appear frequently in publication-ethics cases:

The "no conflicts" reflex. Many authors check the "no conflicts" box without thinking carefully about their relationships. This failure usually stems from not understanding what counts as a conflict instead of from deliberate deception. The remedy is to work through a systematic assessment like the one described above.

The narrow interpretation. Some authors disclose only direct funding and ignore consulting, advisory roles, stock ownership, and intellectual commitments. This narrow interpretation leaves significant conflicts undisclosed and can create problems if the conflict is later discovered.

The "everyone knows" assumption. Some authors assume that because their relationships are well known in their field, formal disclosure is unnecessary. This assumption is incorrect. Journals require written disclosure regardless of how well known the relationship may be.

The late disclosure. Some authors disclose conflicts only after being asked by an editor or reviewer. Late disclosure creates the impression that the author was trying to hide the conflict and can damage credibility even when the conflict itself is minor.

The vague statement. Some authors write statements like "I have relationships with several companies in this field" without specifying the nature of those relationships. Vague disclosure is nearly as problematic as no disclosure because readers cannot assess the potential for bias.

The undisclosed change. Some authors disclose conflicts at submission but fail to update their disclosure when circumstances change during the review process. If you acquire a new financial interest while your manuscript is under review, you must inform the editor.

Limitations of Conflict Disclosure

Disclosure is an important tool for maintaining credibility, but it has real limitations that you should understand.

Disclosure does not eliminate bias. Even when a conflict is fully disclosed, the author's judgment may still be unconsciously influenced. Disclosure simply alerts readers to the possibility of bias so they can interpret the review with appropriate caution.

Disclosure is only as good as the author's self-awareness. If you do not recognize a conflict, you cannot disclose it. This limitation is why systematic self-assessment is important and why some journals ask authors to complete detailed disclosure forms that prompt them to consider various types of conflicts.

Disclosure policies vary across journals. What one journal requires may differ from what another journal expects. You must check the specific requirements of your target journal instead of assuming that a standard approach will work everywhere.

Disclosure does not address all ethical concerns. A literature review can be biased in ways that have nothing to do with conflicts of interest. Poor search strategies, selective inclusion, and inadequate quality assessment can all produce misleading conclusions even when the author has no conflicts to disclose.

Institutional policies may impose additional requirements. If your review is funded by a government agency or conducted as part of your employment, your institution may have conflict-of-interest policies that go beyond journal requirements. You are responsible for understanding and following those policies.

Welfare and Safety Context for Life-Science Reviews

In the life sciences, literature reviews often inform decisions that affect animal welfare, food safety, and public health. This context raises the stakes for conflict disclosure.

A review of evidence on pain management in livestock, for example, may influence veterinary practice and animal welfare standards. If the reviewer has financial ties to a particular analgesic product, readers need to know that to assess whether the review's conclusions are balanced. Similarly, a review of evidence on antibiotic alternatives may influence decisions about disease management that have implications for both animal welfare and antimicrobial resistance.

The National Institutes of Health data management and sharing policy emphasizes the importance of transparency in research. While this policy focuses on data sharing, the underlying principle applies to all aspects of research integrity, including conflict disclosure. Transparent reporting of conflicts is part of the broader commitment to research transparency that funding agencies and journals expect.

For animal owners and producers who read literature reviews, conflict disclosure is a practical tool for evaluating the reliability of the information they are using to make management decisions. A review that discloses a relevant conflict can still be useful, but the reader should weigh the conclusions with awareness of the author's relationships.

Professional Escalation Criteria

There are situations where you should seek additional guidance about conflicts of interest instead of making the decision on your own.

Consult your institution's research integrity office if you are uncertain whether a relationship constitutes a conflict. Research integrity officers have experience with these questions and can help you apply institutional policies.

Contact the journal editor before submission if you have a complex or unusual conflict situation. Editors can advise you on how to handle the disclosure and whether the journal will consider your review given the conflict.

Seek guidance from the Committee on Publication Ethics if you encounter an ethical dilemma that your institution and the journal cannot resolve. COPE provides resources for handling publication-ethics issues, including conflicts of interest.

Escalate to your funding agency if you are uncertain about whether a conflict must be reported under the terms of your grant. The National Institutes of Health provides guidance on financial conflict-of-interest requirements for funded researchers, and your program officer can help you understand your obligations.

Consider withdrawing from the review if you have a conflict so severe that you cannot review the literature objectively. This decision is difficult, but it is sometimes the most ethical choice. A review written by someone with an unavoidable conflict may do more harm than no review at all.

Frequently Asked Questions

What is the difference between a conflict of interest and a bias in a literature review?

A conflict of interest is a relationship or circumstance that could create bias, while bias is the actual distortion of judgment that may result. You can have a conflict of interest without being biased, and you can be biased without having a conflict of interest. Disclosure addresses the conflict, but it does not guarantee that bias has not occurred.

Do I need to disclose a conflict if my review concludes that the conflicted product is not effective?

Yes. The conclusion does not eliminate the conflict. A reader might reasonably wonder whether the conclusion was influenced by the conflict, and the disclosure allows readers to assess the review with that possibility in mind. The disclosure is required regardless of the direction of your conclusions.

What should I do if I discover an undisclosed conflict after my review has been published?

Contact the journal editor immediately. Explain the situation and provide the details of the conflict. The editor will advise you on the appropriate course of action, which may include publishing a correction or adding a conflict-of-interest statement to the published article. Prompt action is important because it demonstrates good faith.

Can I review literature in an area where I have published extensively?

Yes, but your prior publications constitute an intellectual conflict that should be disclosed. Extensive prior publication on one side of a debate does not disqualify you from reviewing the literature, but readers should know about your intellectual investment in the topic. The disclosure should be specific about the nature and extent of your prior work.

Does a small consulting fee need to be disclosed?

Yes. There is no minimum threshold for disclosure. Even a small consulting fee creates a financial relationship that could reasonably be perceived as affecting your judgment. The journal's disclosure form will typically ask about all financial relationships, regardless of amount.

What happens if I fail to disclose a conflict and it is discovered later?

The consequences depend on the severity of the conflict and the policies of the journal. Possible outcomes include rejection of the manuscript, retraction of a published article, a note of concern from the journal, and damage to your professional reputation. In cases involving funded research, your institution and funding agency may also take action.

How do I disclose a conflict that involves a family member?

Disclose the relationship and explain its nature. For example, you might write that your spouse is employed by a company whose product is discussed in the review. The disclosure should be specific enough that readers understand the relationship and can assess its potential to affect your judgment.

Should I disclose conflicts in the cover letter as well as in the manuscript?

Yes. Many journals expect disclosure in both places. The cover letter gives the editor an early opportunity to assess the conflict and determine whether the journal can consider the review. The manuscript disclosure ensures that the information is available to reviewers and readers.

Using the Evidence

Source	Best use in this topic	Important limitation
Research Methods Resources	official guidance	Check the linked page for current local requirements
EQUATOR Network	official guidance	Check the linked page for current local requirements
Core Practices	official guidance	Check the linked page for current local requirements

References and Further Reading

Research Methods Resources. National Library of Medicine.
EQUATOR Network. EQUATOR Network.
Core Practices. Committee on Publication Ethics.
NIH Grants and Funding. National Institutes of Health.
ORCID for Researchers. ORCID.
Data Management and Sharing Policy. National Institutes of Health.
NCBI Literature Resources. National Center for Biotechnology Information.
PubMed. National Library of Medicine.

This article is educational and does not replace institutional policy, professional advice, or applicable safety and regulatory requirements.