Guidance on navigating the research gap in medical literature and points of caution

INTRODUCTION

A research gap is a lack of knowledge within the community about a lingering scientific problem or topic. The sources of this knowledge gap, also known as the evidence gap, could be attributed to a lack of published research on a topic or study design flaws and a lack of methodological rigor in the published literature. Another overlooked source of research gaps is misreporting or misinterpretation of the conclusions of published literature. The previous can result in a lack of evidence, or in conflicting or unreliable evidence.^[1]

A compelling introduction informs readers of the significance and potential impact of the presented research. A vague or insufficient introduction may overshadow the importance and novelty of a research point. A well-constructed introduction section should provide relevant background information, accurately cite relevant literature, unravel all novel facets of the research gap, and propose a practical strategy for closing it. The introduction should conclude with clear, well-defined objectives [Figure 1].^[2-5]

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Figure 1:

A roadmap to writing a purposeful introduction of a medical manuscript. Adapted from El-Sobky, 2021.

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Accurate delineation of the research gap or problem can alert public health authorities to shortcomings in the system and help identify and address deficiencies in national disease surveillance programs. Ultimately, bridging the research gap could positively influence the quality of life of the patients concerned. Moreover, it could help develop more efficient treatment modalities, reflect on health economics, and improve resource utilization.^[1,2] The clear identification of the research gap could help readers judge the appropriateness of the selected research design and methodological approach in regard to study type, sampling methods, and outcome tools. The accurate delineation of a research gap in a particular specialty can spark innovative or uninvestigated research ideas across other medical specialties. The research or knowledge gap can be attributed to deficiencies in three fundamental research processes, namely (1) research design, (2) research performance, and (3) research reporting/writing. Bridging a lingering research gap requires adequate identification, analysis, and interpretation of the contributing factors. This could be achieved through a comprehensive and well-targeted literature review [Figure 2].^[5] For instance, multilevel orthopedic surgery for children with cerebral palsy is widely practiced and effective in improving gait parameters and function on the short- and intermediate term. However, its long-term outcomes, especially in adults with cerebral palsy, remain relatively underexplored, leaving a significant research design gap.^[6]

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Figure 2:

How to present and stratify the research gap in the introduction. (Adapted from El-Sobky, 2021).

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The objective of this paper was to provide guidance on the essential steps required to elaborate a clear and scientifically valid research gap and a research question thereof. Furthermore, we aimed to highlight the relevant areas of concern that need to be addressed.

HOW TO TACKLE THE LITERATURE CONTROVERSY

Pinpointing the nature of the literature controversies or deficiencies can simultaneously reveal the innovative aspects of the research point. Research gaps can result from flaws in the study design/plan or research execution. For example, a thorough literature review may reveal that deficient study designs are a main cause of the insufficient evidence on the accuracy of a diagnostic test or the efficiency of a treatment modality. Failure to neutralize the effects of cofounding variables on the investigated variables is a common methodological design or performance flaw.^[7,8] For instance, failure to create homogeneous study groups in a matched comparative study or a randomized control trial can compromise evidence on the comparative effectiveness of a treatment modality or on the cause-and-effect relationship, respectively. This methodological pitfall could stem from a defective research design or flaws in real-time research execution. Therefore, overcoming deficiencies in previous study designs will likely yield stronger evidence. This represents an innovative dimension of the research work. Furthermore, a lack of credible evidence may be due to non-technical limitations such as shortcomings in research infrastructure, administrative and health system issues, and funding challenges [Figure 3].^[7,8]

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Figure 3:

Navigating the research gap.

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Misreported, misinterpreted, or misworded study conclusions are important contributors to the knowledge gap. Conclusions of abstracts or summaries should not be taken for granted. They should instead be evaluated against the study’s methodology, results, and stated objectives as reported in the full-text article. The aim is to ensure that the conclusions of any published study are supported by its methodology and results.^[8-11] For example, the undue generalization of a study’s conclusions to other patient populations or diseases not originally investigated could lead to the dissemination of misinformation. Routinely equating statistical significance to clinical significance is another cause of misleading conclusions. Likewise, interpreting mere associative relationships between study variables as a causal relationship – cause-and-effect – can lead to misleading conclusions.^[9,10,12]

The retraction of an alarming and exceptionally high number of coronavirus (COVID-19) papers is a clear example of the importance of vetting the literature for methodological rigor. This is aimed at spotting unverified or unsupported research claims, unduly generalized conclusions, and unjustified treatment recommendations that should always be based on the study’s context and in view of its limitations.^[7,8,11] Scientific evolution is a cumulative process in which novel research builds upon previously tested or investigated hypotheses and research ideas. However, a complete lack of clinical evidence on the safety or efficacy of a potential drug therapy or a novel surgical treatment modality presents a challenging knowledge gap. Bridging such knowledge should be based on sound conceptual or academic hypotheses. An exploratory or testable hypothesis-generating animal/pre-clinical research may be required in such cases.^[13]

RESEARCH GAP IN VIEW OF THE REPLICATION CRISIS

The reproducibility or replication crisis in science is defined as the inability of other researchers to successfully replicate the findings of previously published studies, thus casting doubt on the validity of the original studies’ conclusions. It could also cast doubt on evidence linked to established scientific theories.^[14,15] This applies to experimental, preclinical, and clinical research.^[14,16] The potential causes of this reproducibility crisis have been attributed to inherent methodological or design weaknesses of the original studies, such as small or statistically underpowered sample sizes, improper implementation of statistical methods, publication bias, failure of strict adherence to uniform research reporting guidelines, and lack of information necessary to be reproduced, namely raw data and materials.^[16-21] The notion that the reproducibility/replication crisis is an indicator of or synonymous with skeptical or unverified research findings has been challenged.^[22,23] Arguably, successful research replication could be impractical or challenging, given the complex interaction between known and unknown confounding variables, environmental, and racial considerations, among other potentially uncontrollable real-time research settings [Figure 3].^[14,22]

In addition, it is important to maintain a balance between local research resources and settings, and disease uncommonness on the one hand and the strict implementation of statistical protocols pertaining to powered sample size calculations.^[12] Consequently, the reproducibility crisis has been attributed at least in part to substandard or questionable research practices in published studies, such as selective or unplanned collection, analysis, or reporting of data, e.g., P-hacking, failure to delineate a clear research gap, writing a biased introduction (citation bias), and linguistic spin of study conclusions, among others.^[9,24] Substandard or questionable research practices could lead to the propagation of unverified and occasionally misleading study conclusions.^[23,25] Spotting these substandard research practices could help uncover invaluable research gaps that can be filled by designing further studies geared toward enhancing reproducible and transparent research practices.

PITFALLS TO AVOID IN IDENTIFYING THE RESEARCH GAP

It is important to conduct a comprehensive, up-to-date literature search to identify all facets of the knowledge gap. In addition, an accurate and comprehensive delineation of a research gap necessitates a detailed assessment of the methodological quality of key and relevant studies. Basing decisions about the soundness of a study’s methodology and the validity of its results solely on abstracts can be misleading. It is imperative to consult the full text with a critical eye to pinpoint any methodological weaknesses or deficiencies, among others.^[9,10,26,27] Failure to thoroughly read the full text of cited articles can cause misrepresentation of the existing literature. This is because the conclusions of abstracts occasionally contain unverified claims, undue generalizations, linguistic spin, missing data, and unjustified treatment recommendations.^[7,9,10,26] Contrastingly, inaccurate citation practices – by authors of the citing article – can misrepresent or even contradict the conclusions or interpretations made by authors of the cited article. Such citation practices are common in the medical literature and can negatively impact the scientific integrity and credibility of the current medical literature.^[25,28] Importantly, they can undermine the ability of authors to delineate a trustworthy research gap and research question.

Indirect citations are defined as a failure to read and cite the primary source of relevant information. Instead, one cites a secondary source that contains the relevant information. This is another likely means of dissemination of scientific misinformation.^[28] Instead of resorting to indirect citations, authors are advised to methodically consult the primary source article. Similarly, methodologically flawed studies and predatory or questionable journals should not be used as sources of evidence for the existing research gap.^[25,29] The above practices could easily distort the evidence and create an elusive or inflated research gap [Figure 4]. A checklist for identifying the constituents of a research gap is shown in Table 1.

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Figure 4:

Identification of the research gap: Pitfalls to avoid.

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The knowledge gap should be impartially presented to readers. That is, both sides of the literature controversy should be discussed methodically and contextually to avoid bias in reporting or interpreting the current literature. For instance, a biased introduction could distort the knowledge gap and the subsequent research question. Likewise, a biased discussion could arrive at misleading study conclusions.^[8] This could occur consciously or subconsciously. To address this issue, researchers are advised to closely scrutinize the full texts of cited articles (references) to verify the claims, statements, and interpretations made by authors of the citing article and ensure that they are not misrepresented or underreported.^[8,9,25] Publication and citation bias should be taken into consideration, as they could influence the research gap. In that, journals and authors may be more inclined to publish^[30] or cite^[31] articles with positive or affirmative conclusions than those with equivocal or negative ones. Researchers should exercise caution when assessing industry-sponsored interventional drug or device studies. This is particularly relevant to studies sponsored by the manufacturing company and to those in which the interpretation of results, conclusions, or clinical practice recommendations is positive.^[32,33] This is because the reporting and interpretation of the results could be influenced by unperceived conflicts of interest. This could overestimate the true efficacy or efficiency of a treatment modality and blur the true knowledge gap.

CONCLUSION

Delineating a relevant research gap is an intricate and multifold process. Research gaps may arise from deficiencies in the research design, execution, or reporting of published studies. Therefore, study conclusions and interpretations should not be taken for granted. They should rather be weighed against the particulars of research design and execution. Basing research proposal decisions solely on unverified study conclusions and interpretations could lead to the delineation of irrelevant research gaps, wasteful research efforts, and propagation of inaccurate information. Accurate outlining of a relevant research gap requires competent academic critical appraisal skills by researchers. Envisioning research ideas that are relevant to clinical practice or public health requires a thorough and systematic reassessment of the existing literature for breaches of evidence and integrity.