Narrative Reviews and Consensus Processes – Combining the Literature with Expert Opinion and Real-World Experience

Rebecca Hornby, PhD, Oxford PharmaGenesis, Oxford, UK; Brian Falcone, PhD, Oxford PharmaGenesis, Philadelphia, USA; Charlotte Cookson, DPhil, Oxford PharmaGenesis, Oxford, UK

Narrative reviews and Delphi consensus processes play important supporting roles in the collection and analysis of expert opinion by synthesizing the available evidence from the literature and, in the case of consensus papers, combining that with real-world experience to provide a holistic view of current thinking in the field. This article describes the many advantages, and some of the challenges, of undertaking narrative reviews and Delphi consensus initiatives.

The Narrative Review

A narrative review can be defined as a non-systematic summarization of the literature on a specific topic.¹ These publications have been “considered an important educational tool in continuing medical education”² and “the staple of medical literature synthesis.”³ While the narrative review has also been criticized as a vehicle for drug promotion rather than as a meaningful contribution to scientific discourse,⁴ important strides have been made by academia, journals, and the biopharmaceutical industry to deter such a practice. When developed properly and ethically, the narrative review is a focused source of reliable information written by respected experts, and it can provide valuable education to colleagues, health professionals, and others seeking information in the area. These papers can be fundamental in establishing and maintaining the clinical dialogue around a disease state and its treatment, and they can advance the quality of care for patients. Adhering to best practices for developing a narrative review will increase the credibility not only of the work itself, but also of this beneficial means of clinical communication.

What is the importance of selecting appropriate topics for a narrative review?

To preserve the integrity of the narrative review, the topic and content of the manuscript must remain within the boundaries of this article format. Specifically, the goal of the narrative review is to be exactly that – narrative. It should tell a credible, evidence-based story that cites the appropriate existing literature to support the content. There are other publication types to serve as evidence generation and authoritative literature assessments (eg, systematic reviews), as well as to express opinion (eg, editorials, letters); if the topic causes the review to stray too far into either of these domains, its credibility will likely be called into question. Instead, the narrative review should concentrate on educating on a topic, much like a focused textbook chapter (see examples of broadly applicable topics in Table 1 below).

Table 1. Common ideas for narrative reviews

Disease state backgrounder (especially useful for healthcare professionals who encounter patients with the disorder but are not experts on the topic) Overview of considerations for the diagnosis of a disease (often with attention to frequently overlooked signs or symptoms or a call-to-action for under-diagnosed disorders) Balanced presentation of debates in the therapeutic area Discussion and refuting common myths or stigmas associated with a disease Explanations of complex topics associated with the disease area or its treatment (eg, mechanisms of action, endpoint selection) Collections of important reference information (eg, common radiologic signs associated with a disorder, frequently used tables) Strategies for engaging with patients with the disease (eg, questions to ask, concepts to explain) Development rationale and clinical summary of a specific treatment Management strategies for common adverse events associated with a treatment Descriptive explanations of the value of a treatment from a clinical, economic, and humanistic perspective

Considerations for development and submission of narrative reviews

A narrative review should seek to address an unmet need, and as part of a wider publications plan, can add context and understanding to a subject area through the selection and interpretation of the most appropriate literature to support the evidence-based narrative. Development of the narrative review should adhere to good publication practices (GPP3).⁵ As such, the topic of the narrative review should be presented to an author outside of the organization who could be considered an authority in the field, or an author may present a potential topic to the organization; co-authors may also be invited to participate. The authors may develop the content on their own or may use the services of a publications agency funded by the pharmaceutical company; in this circumstance, it is crucial to disclose the participation of the agency, the name of the writer, and the nature of his or her involvement, and that the efforts were funded by the pharmaceutical company.^6,7 Before developing the content, there are other items to consider.

• First, it is recommended that a description of the search strategy is provided. This need not be as rigorous as that required for a systematic review, but should include databases searched, keywords and search strings used, and timeframes of the search. Not only will this ensure that the topic is researched thoroughly when the review is developed, it will also improve the credibility of the paper on peer review and provide a reference point should the research need to be updated during the manuscript’s development.
• Additionally, target journals should be explored early in development. Presubmission inquiries are advisable to avoid an out-of-hand rejection and to help editors.

When the paper is ready for submission, final checks should be performed to ensure that the manuscript is as robust as possible. Ideally, the literature search should be re-run to check whether new relevant findings need to be added. A web search of the topic is appropriate to capture any news related to the issue that may be considered when the manuscript is peer-reviewed. Finally, an examination of the review for overall quality should be performed. Proposed scoring systems, such as the Scale for the Assessment of Narrative Review Articles (SANRA), can provide guidance on factors that reviewers will be considering.¹

Delphi Consensus Initiatives – They’ve Got Our Vote!

A Delphi consensus is a systematic way of combining evidence from the literature with real-world experience from experts in the field. Compared with conventional expert group initiatives, the Delphi consensus can provide deeper insights and more usable outcomes for those of us working in healthcare, researchers, and patients.

What is a Delphi consensus and when is it useful?

The Delphi consensus used today was originally conceived in the 1950s by the Rand Corporation. It is now an established consensus-based technique that allows for the collection and aggregation of informed judgements from a group of experts. The process seeks to reach the correct response through consensus, using rounds of questionnaires to seek anonymous responses, which are then aggregated and voted on. There are no limits on the number of panel members, but group size is generally dependent on availability of experts, resources, and ensuring a geographical spread. Delphi studies with fewer than 10 participants are rarely conducted.⁸ The panel is usually guided by a Chair and steering committee of experts in the field. Figure 1 below shows a generalized process for conducting a Delphi consensus.

Figure 1. Example Delphi consensus process based on a systematic review and statement agreement threshold of ≥ 75% (© Oxford PharmaGenesis 2019)

A well-conducted Delphi consensus, published in a peer-reviewed journal, can provide credibility and support, particularly to areas lacking in evidence in the literature or where expert opinion and real-world experience carry more weight than published literature. Examples include rare diseases, areas of medicine without large scale trials, and new areas of research.

In clinical research, the key aim of a Delphi consensus is to achieve a set of consensus statements that reflect the current thinking in the field. These may go further and make recommendations – for example, to improve diagnosis or treatment of a specific condition or patient group. More generally, the Delphi method can also help deliver forecasts, or indeed any outcome that requires a convergence of opinions.

What is the advantage of a Delphi consensus?

The key advantage of the Delphi method versus other methods of opinion gathering, such as interviews and meetings, is that it brings together experts in a field and allows each to express his or her views and opinions in an anonymous manner, without influence or repercussion. There is strength in having concurrent opinion on a set of draft statements, which are revised and shaped by the groups’ opinion. Furthermore, the equal weighting of responses avoids domination by a single expert, which could lead to bias. Delphi consensus processes are of greatest value to topic-specific areas of expertise, particularly related to decision-making, policy, or long-range forecasting.

What are the challenges you might face when conducting a Delphi consensus?

If there is a generalized lack of agreement among the Delphi panel members, achieving a consensus will be challenging. However, the iterative nature of the Delphi process means this is highly unlikely, as each round of the process allows for revision of the statements in response to comments and feedback from all the Delphi members. Conversely, too great a degree of consensus after the first round of voting could mean the outputs do not challenge the literature or add value based on real-world experience. The size of the Delphi panel should be given consideration; it is important that the panel has enough experts in the field with a range of real-world experience and representative of the global picture (where appropriate), while being of a group size that remains manageable. A Delphi consensus process is complex, with multiple voting rounds and potentially many participants from numerous countries; so, it requires a strong coordinating team with clear sight of the objectives to keep the process on track.

Post-Delphi activities are key to success

A range of post-consensus activities can help to validate and disseminate the Delphi consensus outcomes. These should be considered when developing a communications plan and may include surveying generalists in the field to compare current thinking with expert opinion, congress activities, social media activity notably to patient and specialist organizations, health policy initiatives, and patient engagement activities.

Delphi Consensus Initiatives – Final Thoughts and Examples

For areas of healthcare requiring synthesis of evidence from the literature with real-world experience from experts in the field, a Delphi consensus offers an excellent approach to achieving a convergence of opinions. The outputs from Delphi consensus initiatives will help guide developments in clinical best practice, ultimately resulting in meaningful change for patients.

Some examples of Delphi consensus initiatives, including from a recent consensus panel, are provided in the side bar below for further information.

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Examples of Delphi Consensus Initiatives

Delphi consensus initiatives have yielded consensus papers across a broad range of therapy areas, including: Gaucher disease,⁹ asthma,¹⁰ ulcerative colitis,¹¹ gastroesophageal reflux disease (GERD),^12-14 multiple sclerosis, and hearing loss. These Delphi initiatives are well cited in the literature.^10-16

A recent Delphi consensus panel was convened to explore the use of unilateral cochlear implants (CIs) in adults with bilateral sensorineural hearing loss (SNHL). While hearing aids are effective for many individuals with hearing loss, those affected by bilateral severe, profound, or moderate sloping to profound SNHL may not receive adequate benefit from hearing aids. However, most adults with hearing loss are not receiving CIs even though they would benefit from them. The aim of the Delphi process was to develop consensus statements on the reasons for the under-provision of CIs (which may include low awareness of the benefits of CIs among the individuals with SNHL and healthcare professionals, and a lack of specific referral pathways¹⁷) and the impact on individuals with hearing loss (eg, reduced quality of life¹⁷), and to agree on recommendations for improving CI provision in this group.

To explore this, 30 international experts were recruited, including a Chair and four steering committee members, who guided the process and decision-making. The final of three voting rounds was held at a face-to-face meeting where all statements were discussed, voted on, and endorsed. This resulted in the agreement of 20 consensus statements that will form the basis of an international peer-reviewed publication, currently in development. Going forward, it is hoped this will form the first step towards the creation of much-needed best clinical practice guidelines for the use of CIs in adults, helping those with hearing loss to gain greater access to the support they need.

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Acknowledgments

The authors would like to thank Richard White, MA, PhD (Oxford PharmaGenesis Ltd) for contributions to this article.

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