The OHStat Guidelines for Reporting Observational Studies and Clinical Trials in Oral Health Research: explanation and elaborati

Abstract
Adequate and transparent reporting is necessary for critically appraising research. Yet, evidence suggests that the design, conduct, analysis, interpretation, and reporting of oral health research could be greatly improved. Accordingly, the Task Force on Design and Analysis in Oral Health Research—statisticians and trialists from academia and industry—empaneled a group of authors to develop methodological and statistical reporting guidelines identifying the minimum information needed to document and evaluate observational studies and clinical trials in oral health: the OHstat Guidelines. Drafts were circulated to the editors of 85 oral health journals and to Task Force members and sponsors and discussed at a December 2020 workshop attended by 49 researchers. The final version was subsequently approved by the Task Force in September 2021, submitted for journal review in 2022, and revised in 2023. The checklist consists of 48 guidelines: 5 for introductory information, 17 for methods, 13 for statistical analysis, 6 for results, and 7 for interpretation; 7 are specific to clinical trials. Each of these guidelines identifies relevant information, explains its importance, and often describes best practices. The checklist was published in multiple journals. The article was published simultaneously in JDR Clinical and Translational Research, the Journal of the American Dental Association, and the Journal of Oral and Maxillofacial Surgery. Completed checklists should accompany manuscripts submitted for publication to these and other oral health journals to help authors, journal editors, and reviewers verify that the manuscript provides the information necessary to adequately document and evaluate the research.

Key Words

Publishing/∗standards
research design/standards
statistical data interpretation
comparative studies
retrospective studies

“Large proportions of articles contain errors in the application, analysis, interpretation, or reporting of statistics or in the design or conduct of research.”1
Oral health research is not immune to this criticism. For example, a 2009 review of 95 randomized controlled trials (RCTs) published in the leading journal in each of 6 dental specialties found generally suboptimal reporting of key Consolidated Standards for Reporting Trials (CONSORT) guidelines.2
In another review, “spin”—nonstatistically significant results reported as “clinically important”—was assessed in the abstracts of 75 RCTs published in 10 leading dental journals. Of the 75 trials, 17 incorrectly presented a “statistically nonsignificant result for the primary outcome as showing treatment equivalence or comparable effectiveness” and 2 emphasized the conclusions of a secondary outcome when the primary outcome was not statistically significant.3
Additionally, a report of quality and spin in RCT abstracts in the periodontal-cardiovascular field found poor adherence to CONSORT guidelines, with 87% of trials not reporting on the primary outcome and 86% of trials showing at least 1 form of spin in the results and/or conclusions.4
Thus, “overall, dental journals show low reporting of quality-related characteristics with high variation that is journal-dependent.”5
Although oral health research is similar to clinical research in other fields, many dental studies have design characteristics that can confound analysis. For example, the unit of analysis can be a single tooth, multiple teeth, individual tooth sites, or a single patient. In longitudinal studies, teeth can be lost without disqualifying the participant from the study, and perhaps uniquely in human research, observational units may be added through the primary and permanent dentition process. Another unusual study design in oral health research is the split-mouth study.6
A review of 119 such studies found improved reporting across 2 decades, but overall quality “was still below the acceptable level”: 85% did not provide a sample size calculation, 76% did not identify a primary outcome, 61% used inappropriate statistical methods that did not consider the correlated data, and 38% did not justify the design.7
A common approach to improving reports of biomedical research is to use a checklist of reporting guidelines. Checklists can remind authors to report key elements of a study and help reviewers find where each guideline is addressed when evaluating a manuscript. Most such guidelines are modeled after the CONSORT Statement for reporting randomized trials, first published in 19968
and most recently updated in 2010.9
Also of interest to this document is the STROBE Statement for reporting observational studies.10
Use of the CONSORT Statement has been associated with improved reporting of RCTs.11
,12
However, the EQUATOR Network website lists over 550 checklists.13
Thus, there appeared to be a need for a consolidated guideline that could address the main issues in the most common study designs in oral health.
Accordingly, members of the Task Force on Design and Analysis in Oral Health Research14
began to develop guidelines for reporting clinical studies in oral health in 2019. The process of development is described in the OHStat Statement.15
Drafts were circulated to editors of 85 oral health journals and to Task Force members and sponsors. The draft was discussed at a December 2020 workshop, attended by 49 researchers. The revision was circulated to the writing group and approved by the Task Force. As with other guidelines, the recommendations for reporting oral health research should 1) inform authors of the information needed to document and publish their research, 2) allow readers to assess the validity of the research or at least the credibility of the authors, 3) make the research process transparent, and 4) ideally, provide links to the information needed to replicate the study.
The target audiences for the OHStat Guidelines are authors, reviewers, and journal editors. Authors are advised to include the completed OHStat checklist when submitting a manuscript for publication. Journal editors and reviewers may also wish to consult these and other guidelines when evaluating a manuscript and should insist on complete adherence to the guidelines within journal page limits, word limits, or in supplemental information. Critical appraisal and interpretation of observational studies and clinical trials in oral health will improve with an understanding of the details that support study validity. The purpose of this article is to provide the rationale and scientific background for each item. The terminology used is that provided in the original CONSORT Explanation and Elaboration document.16

The Ohstat Statement: Explanations And Elaborations
Identifying information
The primary purpose of identifying information—the title and abstract—is to help readers make an informed choice about whether to read an article. Not so obvious is that this information should also help readers decide not to read an article. Thus, titles should identify the relationship that was studied. The title should not attempt to “capture the reader’s attention” with anything other than an accurate description of the research. Abstracts should not “highlight the research” but, again, should summarize it accurately so readers will know what to expect if they read the article.17

1.
Title: Space permitting, identify the research design in the title.

The strength of evidence for health care interventions is limited by the study design. Including this information in the title helps with critical appraisal by assisting readers decide whether to read the article. Character limits notwithstanding, try to include as many of the SPICED-T elements as possible: Setting, Patients, Intervention, Comparator, Endpoint, Design, and sometimes Time frame.18
A title can easily be shortened by removing the least important element. If applicable, some key elements must always be included in the title and abstract (e.g., single-sex studies).

2.
Abstract: Provide a structured abstract, as specified by the journal.

The International Committee of Medical Journal Editors (ICMJE) recommends including a structured abstract when reporting original research.19
Such abstracts have 5 or more headings, and journals may specify which headings to use. Usually, only the results and conclusions require complete sentences. However, the form of the abstract will be specified by the individual journal.

3.
Consistency: Confirm that all information in the abstract is identical to that in the article, especially the conclusions.

Many studies have found important discrepancies between the abstract and the full article.20
Because abstracts are often separated from the full article, the information they contain needs to be identical to that in the full article. The conclusions, results, and objectives all need to be consistent throughout the manuscript.
The classic IMRaD structure of scientific articles (Introduction, Methods, Results, and Discussion) is well known, and the OHStat Guidelines emphasize the reasons for this organization. In 1965, Sir Austin Bradford Hill stated in an editorial board meeting of the BMJ that the structure of a scientific paper is built around the answers to 4 questions: “Why did you start, what did you do, what did you find, and what does it mean?”21
Introduction: Why Did You Start?21
After the title, the introduction is the most important and least-appreciated part of the scientific article. A good introduction can be enormously useful because it prepares readers to understand the paper, orients them to the research by establishing the need and importance of the study, indicates in general how the need was addressed, and tells readers what to expect if they continue to read the article.

4.
Problem: Describe the background, nature, scope, and importance of the problem addressed by the research.

Describe the historical, social, medical, ideological, or public health contexts of the problem. Indicate how serious and prevalent it is, as well as its consequences, implications, and whom it affects.
“Little is known about . . .” is rarely a good justification for doing research. A simple lack of knowledge is not sufficient to explain why a relationship needs to be studied or why a research report should be taken seriously.22
Novice readers may need the background to understand the problem; experts expect a compelling justification of the research. The background in the Introduction should support a problem statement—the gap in knowledge or an untapped potential—that stimulated the research.

5.
Objectives: State the specific research objectives, including any prespecified hypotheses, in terms of a clinically important outcome measure or measures.

The problem statement in the Introduction should support the choice of the primary outcome—the variable whose change in value is of interest and why it is clinically or practically important. The specific and measurable objectives should determine the methods of the research.
Methods: What Did You Do?
The purpose of the Methods section is to tell how the research question was addressed. The thought that a clear and transparent Methods section would allow someone to replicate the study is laudable but often not realistic, given the word limitations of a typical journal article, even with supplemental information. Instead, it may be better to tell readers where to obtain copies of the protocol, the statistical analysis plan, and the original data set. In an article, a more reasonable goal is to provide enough information to establish the adequacy of the methods and, in so doing, establish the credibility of the authors as careful and thoughtful researchers.

6.
Design: Describe the overall study design and any variant (e.g., split-mouth, crossover, equivalence) and planned subgroup analyses.

To understand the essential aspects of the study, its design should be described in the Methods. The hierarchy of evidence for clinical studies (both observational studies and clinical trials) arranges sources of information and research designs from those with the most control over error, confounding, and bias to those with the least control. We encourage researchers to aim for the highest appropriate level of evidence.23
,24
The hierarchy listed below is one of many versions, although all include essentially the same designs in the same order:25

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Meta-analysis of RCTs
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Systematic reviews
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RCTs
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Cohort studies
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Case-control studies
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Cross-sectional studies
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Case series
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Case reports