The discussion section of a biomedical manuscript is an opportunity to present new research outcomes (including clinical trials outcomes) and their implication to science, or a new perspective on what is already known on the subject and how it impacts future outlook. In addition, an engaging discussion can seed new research ideas and bring in more citations for the research work. Three factors are crucial to make the discussion appealing—Clarity, Novelty and Critique. Journal editors and reviewers evaluate a biomedical manuscript on the basis of its originality, scope, clarity, and implication. Inadequacy in any one of these primary criteria can lead to rejection of the biomedical manuscript and/or delaying dissemination of the results. Research that goes unreported, or is delayed, may undermine the current body of scientific evidence and the health interventions that rely upon it.
Clear interpretation and communication of the data is essential to writing an impactful biomedical manuscript, and utilizing simple language that follows the rules of lean and effective linguistic style is fundamental. One point to keep in mind is that while the research team (Investigator, Statistician and Sponsor-Pharma in case of clinical trials) may be well aware of the results, the rest of the world is not. It is important to provide sufficient context and maintain logical flow of information with clear transitions from one point to the next. Ambiguous statements in the biomedical manuscript discussion may alert the journal editors and reviewers to check for authenticity of the results.
Here are a few examples of how statement clarity in the discussion section can be achieved:
Lack of clarity: “These findings imply that the rates of hydroxyl radical production and its recycling in isoprene oxidation driven by hydrogen bonding and hydrogen tunneling to replenish the hydroxyl pool are equivalent at the lower irradiance, but not equivalent at higher irradiance with the rate of hydroxyl radical production exceeding its recycling back to hydroxyl.”
Edited version: “These findings imply that, at low irradiation, hydroxyl radicals are produced and recycled at the same rate, but at high irradiation, they are produced faster than they can be recycled back to hydroxyl.”
Lack of clarity: “During DNA damage, recognition of H3K4me3 by ING2 results in recruitment of Sin3/HDAC and repression of cell proliferation genes.”
Edited version: “During DNA damage, H3K4me3 recruits ING2 and Sin3/HDAC, which together repress cell proliferation genes.”
Lack of clarity: “Crohn’s disease incidence showed two peak periods: rates are the highest in young people and the elderly.”
Edited version: “In our study we observed a bimodal distribution of Crohn’s disease incidence with two peaks in the age groups of 20 to 29 years and older than 60 years.”
Another caution to heed in the discussion section is to avoid using expressions of belief and rather to use data to support a statement or theory.
Avoid: “We believe this assay result to be true.”
Follow: “We show through our analysis that this assay result is consistent with the empirical evidence.”
A scientific journal editor always stresses upon novelty and uniqueness of the submitted biomedical manuscripts. A mouth dissolving tablet prepared with conventional methods, technology, and or known excipients presents nothing novel until the author conveys something new that adds value to the existing state of information. Also, there is little scientific value in presenting an obsolete study when newer evidence has been published or in presenting secondary analysis that extends or replicates published findings without adding substantial new information. Sometimes studies report already known evidence and position it as ‘novel’ by extending it to a new geography, population, or cultural setting; this may not be acceptable to the high impact peer-reviewed journals. For example, a study may demonstrate for the first time the role of specific cytokines in a particular animal model of organ-specific inflammatory disease, but the findings may be considered to be entirely predictable based on previous studies with other inflammatory disease models.
In the above scenarios, the best approach is to make it clear how your research adds value by providing an answer to a previously unanswered question, finding a solution to an unsolved problem or improving an existing method. The following example demonstrates this point.
Compare the following statements:
Example 1: Our study provides the first demonstration that Enzyme X is specifically expressed in astrocytes and prevents neuronal damage against oxidative stress.
Example 2: It was previously shown that Enzyme X is expressed at high levels in the brain of patients with brain injury (ABC et al., 2009); however, the role of Enzyme X in the brain had not been studied. Our study shows that Enzyme X is exclusively expressed in astrocytes and prevents neuronal damage against oxidative stress.
The first example states what the researcher has found, but does not elaborate how this is important, or whether the finding adds value to existing knowledge. The second example is a better approach, as it summarizes what was known and what was the gap regarding Enzyme X, and then describes how the results characterize the role of Enzyme X, thus expanding existing knowledge.
Authors can engage readers more effectively with a balanced emphasis on the strengths of their research while providing a critical evaluation of its limitations. The most frequently identified threats to internal validity of study results include issues related to study design, methodology and statistical power. Relevant threats to external validity include sample bias and specific characteristics of the study population that limit generalization of the results. It is important to justify how the results answered the hypothesized research gaps and state the future implications of the findings.
The author is the best critique of his or her own work. Drotar et al 20081 quoted that reviewers may assume that if authors do not identify key limitations of their studies, then they are not aware of them. Disclosure of specific and relevant limitations is important and can be done by stepping into the shoes of the journal reviewers. The critique should involve explaining the implications of each limitation in a logical sequence and leading the reader to a valid conclusion.
Examples of specific and relevant limitations:
- The authors did not look at physician characteristics (endocrinologist versus primary care physician etc), and the frequency of follow up (those with closer follow up probably have higher weight loss).2
- A particular question was not included in a survey instrument, which could have revealed additional data.
- Data was not collected regarding concomitant physical therapy, hence synergistic effects of the pharmacotherapy and physical rehabilitation could not be analyzed.
- Effective education had a significant impact on alcohol cessation as part of alcohol and or substance abuse treatment. However, ‘effective education’ has not been defined as only education/counseling sessions or other interventions that induce people to change their behavior.
If applicable, authors may present counterarguments to nullify the primary threats to external validity. For example, if a study was limited by a small sample size, however demonstrated statistically significant findings with a robust effect size, this should be stated.
Using References to Support Novelty and Clarity
The discussion section aims to make conclusions based on the best available scientific evidence, thereby improving clinical decision-making. It weighs strengths and weaknesses of each research project that is reviewed and presented. References cited in this section should explain and justify the unique results of the study. References from peer-reviewed journals or policy documents are preferred over websites, news articles and popular articles. If necessary, authentic government websites may be cited. A discussion of a systematic review or meta-analysis should be written in a non-judgmental manner.
In summary, the principal rule of writing an engaging and effective discussion in a biomedical manuscript is to focus on the reader and maintain a balance between providing too much and not adequate contextual information. There is a need for focused synthesis, organization and interpretation of the findings highlighting the relevant take-home messages. Three factors crucial to making the discussion appealing and effective are: Clarity, Novelty and Critique.
- Dennis Drotar. Editorial: How to Write an Effective Results and Discussion for the Journal of Pediatric Psychology. J Pediatr Psychol (2009) 34 (4): 339-343.
- Examples of reviews rated by Deputy Editors of Journal of General Internal Medicine, Nov 13, 2007. [Link]