EBD Lec 3 PDF

Evidence-based dentistry Lecture 3: Introduction to study designs continue… 6. Non randomized controlled trial It involves the evaluation of an intervention or treatment without randomly assigning participants to different groups. This means that the researchers do not use a random process...

Evidence-based dentistry Lecture 3: Introduction to study designs continue… 6. Non randomized controlled trial It involves the evaluation of an intervention or treatment without randomly assigning participants to different groups. This means that the researchers do not use a random process to determine who receives the intervention and who receives a control or placebo. Advantages: - Can be conducted in situations where randomization is not practical or ethical - Reflects real-world conditions and may provide more generalizable results. Limitations: - Difficult to control for confounding variables that may influence the outcomes. - Participants may be self-selected or assigned to groups based on factors that affect the outcomes. - Limited Causal Inference 7. Randomized controlled trial: The researchers decide randomly as to which participants in the trial receive the new treatment and which receive a placebo, or fake treatment The trial uses a control group for comparison or reference. In the control group, the participants do not receive the new treatment but instead receive a placebo or reference treatment. Considered the gold standard for medical research. Advantages: - It provides the strongest evidence for cause-and-effect relationships between treatment and outcome - Randomization and blinding help reduce bias that can influence results - Can produce Reliable generalizable findings Limitations: - Treatments that are more invasive, involving devices or surgery, may be impossible to mock-up realistically in the comparison group. - Too few people might have a certain disease and also be available for investigation in both treatment and non-treatment groups. - The recruitment of participants to a particular trial may be too difficult. Randomization Refers to the act of randomly assigning subjects in a study to different treatment groups. For example, suppose researchers recruit 100 subjects to participate in a study in which they hope to understand whether or not two different pills have different effects on blood pressure. They may decide to use a random number generator to randomly assign each subject to use either pill #1 or pill #2. Benefits of Randomization: - To control the lurking variables – variables that are not directly included in an analysis, yet impact the analysis in some way. For example, if researchers are studying the effects of two different pills on blood pressure then the following lurking variables could affect the analysis: Smoking habits Diet Exercise By randomly assigning subjects to treatment groups, we maximize the chances that the lurking variables will affect both treatment groups equally. This means any differences in blood pressure can be attributed to the type of pill, rather than the effect of a lurking variable. Block Randomization An extension of randomization is known as block randomization. This is the process of first separating subjects into blocks, then using randomization to assign subjects within blocks to different treatments. Blinding: A technique used in randomized controlled trials (RCTs) to minimize bias and ensure the objectivity of the study. It involves concealing information from participants or researchers to prevent their expectations from influencing the results. There are two main types of blinding: a. Single-blinded: Only the participants are unaware of which treatment they are receiving. b. Double-blinded: Both the participants and the researchers (including those administering the treatments and assessing the outcomes) are unaware of the treatment assignments c. Triple-blinded: participants, researchers and the statistical analytics team ae also unaware of the treatment assignment. 8. Systematic reviews A type of review that uses repeatable methods to find, select, and synthesize all available evidence. It answers a clearly formulated research question and explicitly states the methods used to arrive at the answer. Advantages: Limitations: - They minimize research bias by considering all - They’re time-consuming. available evidence and evaluating each study for bias. - They’re narrow in scope: they - Their methods are transparent, so they can be only answer the precise research scrutinized by others. question. - They’re thorough: they summarize all available evidence. - They can be replicated and updated by others. 9. Meta-analysis A technique to synthesize results from multiple studies. It’s a statistical analysis that combines the results of two or more studies, usually to estimate an effect size. Meta-analyses are particularly valuable when individual study results are inconclusive or contradictory. There are three primary families of effect sizes used in most meta-analyses: a. Mean difference effect sizes: Used to show the magnitude of the difference between means of groups or conditions, commonly used when comparing a treatment and control group. b. Correlation effect sizes: Represent the degree of association between two continuous measures, indicating the strength and direction of their relationship. c. Odds ratio effect sizes: Used with binary outcomes to compare the odds of an event occurring between two groups, like whether a patient recovers from an illness or not. How to conduct Meta-analysis: PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) A reporting guideline designed to improve the transparency and completeness of systematic review reporting. It was created to tackle the issue of inadequate reporting often found in systematic reviews Checklist: PRISMA features a 27-item Flow Diagram: PRISMA also checklist covering all aspects of a meta- includes a flow diagram to visually analysis, from the rationale and objectives to represent the study selection the synthesis of findings and discussion of process, offering a clear, limitations. Each checklist item is accompanied standardized way to illustrate how by detailed reporting recommendations in an researchers arrived at the final set of Explanation and Elaboration document included studies Thank you