Interesting news from research published in the Journal of Dental Research
Interesting news from research published in the Journal of Dental Research.
How Reliable Are the Results of the First Trials in Dentistry?
If you are a dentist, you probably want to keep up with the latest evidence on the best treatments for your patients. You may read clinical trials that compare different interventions and report their effects on various outcomes. But how confident can you be that the results of these trials are accurate and consistent? And how do they compare with the results of later trials on the same topic?
A recent study published in the Journal of Dental Research 1 aimed to answer these questions by assessing the presence of novelty bias in a sample of studies published in periodontology and implant dentistry. Novelty bias is the idea that early trials tend to show larger and more favorable effects than later trials, possibly due to methodological flaws, publication bias, or exaggerated expectations 2. This can pose a problem for clinical practice if dentists base their decisions on the results of early trials without considering the evidence from later trials.
The authors of the study searched for meta-analyses of clinical trials published between August 2015 and August 2020 in periodontology and implant dentistry. A meta-analysis is a statistical method that combines the results of several trials on the same topic to provide a more precise and comprehensive estimate of the effect of an intervention 3. The authors selected meta-analyses that included at least four primary trials and compared the effect estimates of the first trial in each meta-analysis with the pooled effect estimate of the meta-analysis. They also used statistical models to examine whether certain characteristics of the trials, such as sample size, year of publication, funding source, and risk of bias, were associated with the likelihood of novelty bias.
The authors found 92 meta-analyses that met their criteria, covering topics such as caries detection, periodontal disease assessment, implant planning, orthodontic treatment, and facial aesthetics. They found that in 70% of the meta-analyses, the pooled effect estimate was smaller than the corresponding estimate of the first trial, suggesting that early trials tended to overestimate the effects of interventions. However, they also found that there was overlap between the confidence intervals (CIs) of the estimates from the first trial and the meta-analysis in 87% of the cases. A CI is a range of values that indicates how certain we are about an estimate . If two CIs overlap, it means that there is no statistically significant difference between the two estimates . Therefore, even though early trials showed larger effects than later trials, these differences were not always meaningful.
The authors also found that as the number of trials in a meta-analysis increased, the odds of novelty bias decreased. This means that more evidence reduces uncertainty and leads to more conservative estimates. They also found that trials with larger sample sizes, higher risk of bias, and industry funding were more likely to show novelty bias than trials with smaller sample sizes, lower risk of bias, and non-industry funding.
The authors concluded that their findings show evidence of novelty bias in periodontology and implant dentistry, but also highlight the importance of considering the quality and quantity of evidence when interpreting trial results. They recommended that clinicians should be aware of the risk of making decisions based on the information reported in new trials because they may be exaggerated. They also suggested that researchers should follow rigorous methods and standards when conducting and reporting clinical trials to minimize bias and increase trustworthiness.