The power of tests to detect differences between periodontal treatments in published studies

Quality of Reporting Randomized Controlled Trials Published in Three of the Most Citable Periodontal Journals from 2018 to 2022

This study aimed to evaluate the reporting quality of randomized clinical trials (RCTs) in periodontology. Three leading periodontology journals, the Journal of Periodontology (JOP), the Journal of Clinical Periodontology (JOCP), and the Journal of Periodontal Research (JOPR), were selected for this investigation. The RCTs were identified by manually searching for human trial articles published in these three journals. Two authors independently conducted the literature search, and a pre-piloted extraction sheet was used to screen the potential RCTs. The CONSORT checklist guidelines were employed to calculate the score value. Intra-examiner reliability was assessed by scoring a random sample of 10% of the papers in a second round conducted by the first examiner three months after the initial data collection. A search of abstracts published over a five-year period yielded 176 articles that reported RCTs, accounting for 11.7% of all articles published in the three journals. The highest number of RCTs was published in 2020, and more than half of the included RCTs (51%) originated from Europe. Many of the analyzed RCTs inadequately reported almost half of the items on the CONSORT checklist. Furthermore, univariate analysis revealed significant associations between certain factors and the overall CONSORT score, such as publication in JOP (p = 0.048), publication year of 2019 (p = 0.041) and 2021 (p = 0.042), first author from North America (p = 0.016), and RCTs with more than six authors (p = 0.042). Clinical trial research in periodontics has made significant progress in the past five years. However, there is room for improvement in adhering to the CONSORT guidelines.

Statistical Power for Analyses of Changes in Randomized Controlled Trials

Randomized controlled trials (RCTs) are widely recommended as the most useful study design to generate reliable evidence and guidance to daily practices in medicine and dentistry. However, it is not well-known in dental research that different statistical methods of data analysis can yield substantial differences in study power. In this study, computer simulations are used to explore how using different univariate and multivariate statistical methods of analyzing change in continuous outcome variables affects study power, and the sample size required for RCTs. Results show that, in general, analysis of covariance (ANCOVA) yields greater power than other statistical methods in testing the superiority of one treatment over another, or in testing the equivalence between two treatments. Therefore, ANCOVA should be used in preference to change score or percentage change score to reduce type II error rates.

Are sample sizes clear and justified in RCTs published in dental journals?

Sample size calculations are advocated by the CONSORT group to justify sample sizes in randomized controlled trials (RCTs). The aim of this study was primarily to evaluate the reporting of sample size calculations, to establish the accuracy of these calculations in dental RCTs and to explore potential predictors associated with adequate reporting. Electronic searching was undertaken in eight leading specific and general dental journals. Replication of sample size calculations was undertaken where possible. Assumed variances or odds for control and intervention groups were also compared against those observed. The relationship between parameters including journal type, number of authors, trial design, involvement of methodologist, single-/multi-center study and region and year of publication, and the accuracy of sample size reporting was assessed using univariable and multivariable logistic regression. Of 413 RCTs identified, sufficient information to allow replication of sample size calculations was provided in only 121 studies (29.3%). Recalculations demonstrated an overall median overestimation of sample size of 15.2% after provisions for losses to follow-up. There was evidence that journal, methodologist involvement (OR = 1.97, CI: 1.10, 3.53), multi-center settings (OR = 1.86, CI: 1.01, 3.43) and time since publication (OR = 1.24, CI: 1.12, 1.38) were significant predictors of adequate description of sample size assumptions. Among journals JCP had the highest odds of adequately reporting sufficient data to permit sample size recalculation, followed by AJODO and JDR, with 61% (OR = 0.39, CI: 0.19, 0.80) and 66% (OR = 0.34, CI: 0.15, 0.75) lower odds, respectively. Both assumed variances and odds were found to underestimate the observed values. Presentation of sample size calculations in the dental literature is suboptimal; incorrect assumptions may have a bearing on the power of RCTs.

Sample size estimation: an overview with applications to orthodontic clinical trial designs

Proper sample size estimation is an important part of clinical trial methodology and closely related to the precision and power of the trial's results. Trials with sufficient sample sizes are scientifically and ethically justified and more credible compared with trials with insufficient sizes. Planning clinical trials with inadequate sample sizes might be considered as a waste of time and resources, as well as unethical, since patients might be enrolled in a study in which the expected results will not be trusted and are unlikely to have an impact on clinical practice. Because of the low emphasis of sample size calculation in clinical trials in orthodontics, it is the objective of this article to introduce the orthodontic clinician to the importance and the general principles of sample size calculations for randomized controlled trials to serve as guidance for study designs and as a tool for quality assessment when reviewing published clinical trials in our specialty. Examples of calculations are shown for 2-arm parallel trials applicable to orthodontics. The working examples are analyzed, and the implications of design or inherent complexities in each category are discussed.

An assessment of quality characteristics of randomised control trials published in dental journals

OBJECTIVES

The purpose of this study was to investigate the quality of reporting of randomised clinical trials (RCTs) published in dental specialty journals.

METHODS

The journals possessing the highest impact factor (2008 data) in the six major dental specialties were included in the study. The contents of the 24 most recent issues of each journal were hand-searched and research articles identified as randomised controlled trials (RCTs) were selected. Quality evaluation was performed using the modified Consolidated Standards of Reporting Trials (CONSORT) statement checklist. The data were analysed using descriptive statistics followed by univariate and multivariate examination of statistical associations (alpha=0.05).

RESULTS

Ninety-five RCTs were identified with generally suboptimal scores on quality reporting on key CONSORT areas. Significant differences were found among journals with the Journal of Clinical Periodontology achieving the highest score, followed by the American Journal of Orthodontics and Dentofacial Orthopedics. There was a positive association between quality score and number of authors, involvement of statistician/epidemiologist, and multicentre trials.

CONCLUSIONS

The quality scores of RCTs in major dental journals are considered suboptimal in key CONSORT areas. This receives critical importance considering that improved quality of RCTs is a fundamental prerequisite for improved dental care.

Underpowering in randomized trials reporting a sample size calculation

OBJECTIVE

The objective of this study was to determine whether standard deviations (SDs) used in sample size calculations are smaller than those found in the resulting study sample, thereby leading to underpowered studies.

METHOD

The predicted SD used in the sample size calculation and the actual SD of the study sample were recorded for randomized trials recently published in one of four major journals.

RESULTS

Sample SD was greater than predicted SD for 80% of endpoints. About one quarter of trials required five times as many patients as specified in the sample size calculation.

CONCLUSION

Trials reporting sample size calculations for continuous endpoints published in the most reputable medical journals are often underpowered. There seems to be insufficient understanding that the SD of a sample of patients is a random variable, associated with imprecision, that cannot easily be extrapolated from one population to another.

Nonsurgical periodontal therapy in 2000: a literature review

BACKGROUND

This article addresses the advantages and limitations of nonsurgical periodontal therapies to treat patients with mild-to-moderate chronic periodontitis.

TYPES OF STUDIES REVIEWED

Controlled clinical trials were selected that assessed the efficacy of the following treatment methods: mechanical instrumentation, ultrasonic débridement, supragingival irrigation, subgingival irrigation, local drug delivery, administration of systemic antibiotics and host-response modulation. Evidently, data with regard to alterations of probing depth, clinical attachment levels and inflammatory status were evaluated.

RESULTS

Comparison of the data from test and control groups revealed the following results. Manual and ultrasonic débridement can be used to treat most patients with mild-to-moderate chronic periodontitis. Patients who do not practice optimal plaque control can enhance their personal hygiene procedures by using supragingival irrigation. Subgingival irrigation usually does not provide any benefit beyond that achieved with root planing. Systemic and locally delivered antimicrobial agents appear to be most beneficial among patients who do not respond to conventional treatment. Host modulation may enhance root planing modestly.

CLINICAL IMPLICATIONS

The data indicate that most patients with mild-to-moderate periodontitis can be treated with nonsurgical therapies. However, clinicians need to be aware of the limitations of each technique with regard to the magnitude of improvement that it can induce at specific sites.

Contemporary interpretation of probing depth assessments: diagnostic and therapeutic implications. A literature review

This paper addresses the diagnostic and therapeutic implications of increased probing depths. In general, in untreated and treated patients, when deep and shallow probing depths are compared, the data indicate that deep sites are associated with increased bleeding upon probing, elevated subgingival temperatures, higher levels of pathogens, more probing errors, a greater amount of infiltrated connective tissue, reduced ability to remove subgingival deposits with root planing, and diminished effectiveness of oral hygiene to alter the subgingival microbiota. Clinical trials demonstrate that probing depth is not a good predictor of future disease progression. However, deep sites are at greater risk of disease progression than shallow sites in untreated and treated patients. Furthermore, the deeper the probing depth, the greater the risk of future disease progression. Overall, the preponderance of evidence indicates that it is advantageous, but not always necessary, for patients to have shallow probing depths. With regards to surgical reduction of probing depths beyond that attained with non-surgical therapy, clinicians need to consider the advantages (e.g., ease of maintenance, reduced risk of disease progression) and disadvantages (e.g., root sensitivity, cosmetic defects) of treatment procedures. Since numerous variables require consideration (e.g., response to root planing, goals of therapy, acceptable level of risk for future disease progression), treatment decisions will vary depending on the patient and the desired clinical outcome at specific sites.

Definitive vs. exploratory periodontal trials: a survey of published studies

Definitive and exploratory randomized controlled trials (RCTs) have different goals as well as different design and analysis characteristics. The goal of definitive studies is to provide unequivocal evidence of a treatment's tangible benefit to the patient; a pre-trial-specified hypothesis is tested by use of a pre-trial-specified method. The goal of exploratory studies is to elucidate biological treatment mechanisms, to identify promising treatments, and to generate hypotheses for definitive studies; multiple hypotheses are evaluated to extract as much information from the data as possible. The purposes of this study were: (1) to survey selected design and analysis characteristics of randomized controlled periodontal trials published between 1988 and 1992 (n = 86), and (2) to classify trials as exploratory or definitive studies. The peridontal RCTs surveyed were typical of exploratory studies whose primary goal was to elucidate biological treatment mechanisms. Trial reports indicated the testing of multiple hypotheses (> or = 6 hypothesis tests in 70 of the 86 trials) on a variety of biological markers (86 out of 86 trials). The sample size (< or = 30 subjects in 67 out of 86 trials), duration (< or = 6 months in 65 out of 86 trials), and design and analysis characteristics (e.g., an absence of masking in 57 out of 86 trials) were also typical of exploratory studies which strive to obtain quick answers (short duration) at a low cost (small sample size; accept bias for increased efficiency and a lower cost). No definitive trials were identified.(ABSTRACT TRUNCATED AT 250 WORDS)