Risk of bias and magnitude of effect in orthodontic randomized controlled trials: a meta-epidemiological review (original) (raw)
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Objectives Meta-analysis is the gold standard for synthesizing evidence on the effectiveness of health care interventions. However, its validity is dependent on the quality of included studies. Here, we investigated whether basic study design (i.e., randomization and timing of data collection) in orthodontic research influences the results of clinical trials. Study Design and Setting This meta-epidemiologic study used unrestricted electronic and manual searching for meta-analyses in orthodontics. Differences in standardized mean differences (ΔSMD) between interventions and their 95% confidence intervals (CIs) were calculated according to study design through random-effects meta-regression. Effects were then pooled with random-effects meta-analyses. Results No difference was found between randomized and nonrandomized trials (25 meta-analyses; ΔSMD = 0.07; 95% CI = −0.21, 0.34; P = 0.630). However, retrospective nonrandomized trials reported inflated treatment effects compared with prospective (40 meta-analyses; ΔSMD = −0.30; 95% CI = −0.53, −0.06; P = 0.018). No difference was found between randomized trials with adequate and those with unclear/inadequate generation (25 meta-analyses; ΔSMD = 0.01; 95% CI = −0.25, 0.26; P = 0.957). Finally, subgroup analyses indicated that the results of randomized and nonrandomized trials differed significantly according to scope of the trial (effectiveness or adverse effects; P = 0.005). Conclusion Caution is warranted when interpreting systematic reviews investigating clinical orthodontic interventions when nonrandomized and especially retrospective nonrandomized studies are included in the meta-analysis.
Objective The aim of this study was to examine the presence and extent of small study effects and publication bias in metaanalyses (MAs) based on orthodontic studies. Materials and methods Following an extensive literature search, 25 MAs including 313 studies were identified and were possible to be re-analyzed. For the assessment of publication bias, contour-enhanced funnel plots were examined and their symmetry was tested using the Begg and Mazumdar rank correlation and Egger's linear regression tests. Robustness of MAs' results to publication bias was examined by Rosenthal's failsafe N, and adjusted effect sizes were calculated after consideration of publication bias using Duval and Tweedie's "trim and fill" procedure. Results Only few of the originally published MAs assessed the existence and effect of publication bias and some only partially. Inspection of the funnel plots indicated possible asymmetry, which was confirmed by Begg and Mazumdar's test in 12 % and by Egger's test in 28 % of the MAs. According to Rosenthal's criterion, 62 % of the MAs were robust, while adjusted effect estimates with unpublished studies differed from little to great from the unadjusted ones. Pooling of Egger's intercepts of included MAs indicated that evidence of asymmetry was found in the orthodontic literature, which was accentuated in medical journals and in diagnostic MAs.
The reporting quality of Randomised Controlled Trials in Orthodontics
Journal of Evidence Based Dental Practice, 2014
Systematic reviews a b s t r a c t Objectives: Abstracts of systematic reviews are of critical importance, as consumers of research often do not access the full text. This study aimed to assess the reporting quality of systematic review (SR) abstracts in leading oral implantology journals.
PLOS ONE, 2017
A priori registration of randomized clinical trials is crucial to the transparency and credibility of their findings. Aim of this study was to assess the frequency with which registered and completed randomized trials in orthodontics are published. We searched ClinicalTrials.gov and ISRCTN for registered randomized clinical trials in orthodontics that had been completed up to January 2017 and judged the publication status and date of registered trials using a systematic protocol. Statistical analysis included descriptive statistics, chi-square or Fisher exact tests, and Kaplan-Meier survival estimates. From the 266 orthodontic trials registered up to January 2017, 80 trials had been completed and included in the present study. Among these 80 included trials, the majority (76%) were registered retrospectively, while only 33 (41%) were published at the time. The median time from completion to publication was 20.1 months (interquartile range: 9.1 to 31.6 months), while survival analysis indicated that less than 10% of the trials were published after 5 years from their completion. Finally, 22 (28%) of completed trials remain unpublished even after 5 years from their completion. Publication rates of registered randomized trials in orthodontics remained low, even 5 years after their completion date.
Sample size in orthodontic randomized controlled trials: are numbers justified?
The European Journal of Orthodontics, 2013
Sample size calculations are advocated by the Consolidated Standards of Reporting Trials (CONSORT) group to justify sample sizes in randomized controlled trials (RCTs). This study aimed to analyse the reporting of sample size calculations in trials published as RCTs in orthodontic speciality journals. The performance of sample size calculations was assessed and calculations verified where possible. Related aspects, including number of authors; parallel, split-mouth, or other design; singleor multi-centre study; region of publication; type of data analysis (intention-to-treat or per-protocol basis); and number of participants recruited and lost to follow-up, were considered. Of 139 RCTs identified, complete sample size calculations were reported in 41 studies (29.5 per cent). Parallel designs were typically adopted (n = 113; 81 per cent), with 80 per cent (n = 111) involving two arms and 16 per cent having three arms. Data analysis was conducted on an intention-to-treat (ITT) basis in a small minority of studies (n = 18; 13 per cent). According to the calculations presented, overall, a median of 46 participants were required to demonstrate sufficient power to highlight meaningful differences (typically at a power of 80 per cent). The median number of participants recruited was 60, with a median of 4 participants being lost to follow-up. Our finding indicates good agreement between projected numbers required and those verified (median discrepancy: 5.3 per cent), although only a minority of trials (29.5 per cent) could be examined. Although sample size calculations are often reported in trials published as RCTs in orthodontic speciality journals, presentation is suboptimal and in need of significant improvement.
Clinical Oral Investigations, 2014
Objective The aim of this study was to examine the presence and extent of small study effects and publication bias in metaanalyses (MAs) based on orthodontic studies. Materials and methods Following an extensive literature search, 25 MAs including 313 studies were identified and were possible to be re-analyzed. For the assessment of publication bias, contour-enhanced funnel plots were examined and their symmetry was tested using the Begg and Mazumdar rank correlation and Egger's linear regression tests. Robustness of MAs' results to publication bias was examined by Rosenthal's failsafe N, and adjusted effect sizes were calculated after consideration of publication bias using Duval and Tweedie's "trim and fill" procedure. Results Only few of the originally published MAs assessed the existence and effect of publication bias and some only partially. Inspection of the funnel plots indicated possible asymmetry, which was confirmed by Begg and Mazumdar's test in 12 % and by Egger's test in 28 % of the MAs. According to Rosenthal's criterion, 62 % of the MAs were robust, while adjusted effect estimates with unpublished studies differed from little to great from the unadjusted ones. Pooling of Egger's intercepts of included MAs indicated that evidence of asymmetry was found in the orthodontic literature, which was accentuated in medical journals and in diagnostic MAs.
The European Journal of Orthodontics, 2015
The aim of this study was to explore demographic characteristics of systematic reviews (SRs), meta-analyses (MAs), and randomized controlled trials (RCTs) published in orthodontic journals with an impact factor (IF). Materials and methods: An electronic search was developed and implemented to identify all the SRs, MAs, and RCTs published in the seven orthodontic journals with an IF. No restrictions were applied regarding language, publication date, or publication status. The initial search generated 1147 articles, which were reviewed by three authors in order to determine if they met the inclusion criteria. Five hundred and fifty-seven articles were included in the final analysis. Type of article, name of journal, year of publication, number of authors, country of origin, and primary affiliation were recorded. Associations between those parameters were tested with the Pearson chi-square test for independence at the 0.05 level of significance. Results: The majority (72%) of this kind of articles published in the orthodontic literature were RCTs, followed by SRs (20.1%) and MAs (7.9%). Approximately 77.2% of all RCTs, SRs, and MAs were published between 2004 and 2013, and 72.9% came from orthodontic departments. More than 80% of all articles were collaborative efforts between three or more authors. Contributions from Asia, South and Central America significantly increased during last decade, while contributions from North America decreased by almost 30%. Conclusions: Most RCTs, MAs, and SRs have been published between 2004 and 2013, indicating a significant improvement of the orthodontic literature during the last decade. Asia, South and Central America have significantly increased their contributions to the high evidence orthodontic literature since 2004.
European journal of orthodontics, 2015
Summary AIM : To analyse meta-analyses included in systematic reviews (SRs) published in leading orthodontic journals and the Cochrane Database of Systematic Reviews (CDSR) focusing on orthodontic literature and to assess the quality of the existing evidence. Electronic searching was undertaken to identify SRs published in five major orthodontic journals and the CDSR between January 2000 and June 2014. Quality assessment of the overall body of evidence from meta-analyses was conducted using the Grading of Recommendations Assessment, Development and Evaluation working group (GRADE) tool. One hundred and fifty-seven SRs were identified; meta-analysis was present in 43 of these (27.4 per cent). The highest proportion of SRs that included a meta-analysis was found in Orthodontics and Craniofacial Research (6/13; 46.1 per cent), followed by the CDSR (12/33; 36.4 per cent) and the American Journal of Orthodontics and Dentofacial Orthopaedics (15/44; 34.1 per cent). Class II treatment was ...
The European Journal of Orthodontics, 2011
Randomization is a key step in reducing selection bias during the treatment allocation phase in randomized clinical trials. The process of randomization follows specific steps, which include generation of the randomization list, allocation concealment, and implementation of randomization. The phenomenon in the dental and orthodontic literature of characterizing treatment allocation as random is frequent; however, often the randomization procedures followed are not appropriate. Randomization methods assign, at random, treatment to the trial arms without foreknowledge of allocation by either the participants or the investigators thus reducing selection bias. Randomization entails generation of random allocation, allocation concealment, and the actual methodology of implementing treatment allocation randomly and unpredictably. Most popular randomization methods include some form of restricted and/or stratified randomization. This article introduces the reasons, which make randomization an integral part of solid clinical trial methodology, and presents the main randomization schemes applicable to clinical trials in orthodontics.