Evidence-Based Dentistry Lecture 2: Introduction to Study Designs PDF

Evidence-based dentistry Lecture 2: Introduction to study designs  Case study Types of epidemiological Descriptive Case series...

Evidence-based dentistry Lecture 2: Introduction to study designs  Case study Types of epidemiological Descriptive Case series Observation al studies Cross sectional studies Analytical Cohort Non- randomized Case control experimental controlled studies trials Randomized controlled trials Systematic Literature reviews reviews Meta- analysis  1. Case study or report: It’s a detailed study of a specific case A case study is a qualitative research method that involves the in- depth exploration and analysis of a particular case, which can be an individual, group, organization, event, or community. Advantages: Limitations: - Help to generate hypotheses about the - Limited generalizability causal - Biased sampling relationships between different factors - Limited control and outcomes - Resources intensive - Document certain phenomenon, symptom or a rare drug reaction - informing practice or policy - Provide rich data and a holistic perspective How to write a case report: step 1: Select a case Once you have developed your problem statement and research questions, you should be ready to choose the specific case that you want to focus on. Step 2: Build a theoretical framework While case studies focus more on concrete details than general theories, they should usually have some connection with theory, This way the case study is not just an isolated description, but is integrated into existing knowledge about the topic. It might aim to: Exemplify a theory by showing how it explains the case under investigation Expand on a theory by uncovering new concepts and ideas that need to be incorporated Step Challenge a theory 3: Collect yourby exploring an outlier case that doesn’t fit with established data assumptions There are many different research methods you can use to collect data on your subject. Step 4: Describe and analyze the case In writing up the case study, you need to bring together all the relevant aspects to give as complete a picture as possible of the subject. 1. Case study or report: 2. Case series: It tracks a group of patients with a similar condition or treatment. It's often used to: Describe a new disease or condition, Identify unique symptoms, characteristics, or progression patterns, Report on the effectiveness of a new treatment, Observe outcomes Advantages: - Observational - Descriptive - Retrospective or prospective - Usually a seed for RCT Limitations: - No control group: This makes it difficult to establish cause-and-effect relationships. - Selection bias: Patients may not be representative of the entire population. - Confounding factors: Other factors could influence the observed outcomes. 3. Cross sectional study It looks at a population at a single point in time, like taking a slice or cross-section of a group, and variables are recorded for each participant. Main objective is to determine the prevalence such as assessing frequency of a disease Often useful when looking for an ethical approach to investigate harmful situations that would otherwise be unethical if inflicted on a participant Advantages: Limitations: -Efficient -Can not establish causation -Descriptive -Time-bound -Hypothesis generation -Prevalence bias -Large sample size -Rare diseases and conditions can be hard to investigate using a cross-sectional study design 4. Cohort study It’s an observational and analytical study. In these studies, the investigator did not assign exposures, a comparison group was used, and the exposure was the starting point for the research. The incidence of disease in the exposed group is compared with the incidence of disease in the unexposed group. Advantages: - the only observational study design that Limitations: directly investigates risk of disease and - Not appropriate for rare diseases or those that the factors contributing to it. take a long time to develop e.g. - Ethically safe. mesothelioma. - Multiple outcomes can be measured. - Not appropriate for studying multiple - They are good for rare types of exposures. exposures, e.g. an exposure to a - Can be costly and time consuming. chemical spill in a factory. 4. Cohort study The two groups of cohorts (exposed and un-exposed) are followed prospectively over time to track the development of new disease. Prospectiv Example: In a prospective cohort study researchers compared e four different groups of women (two at-risk groups, two low-risk groups) to investigate which groups were more likely to develop PTSD symptoms after a birthing event. Cohorts are defined from a previous point in time, and are not followed up in the future. Information or data is collected from past clinical records and the outcome of interest is investigated. Retrospect Useful for tracking the progress of a disease with a long latency period. ive Example: In a retrospective cohort study researchers used previously collected data to investigate whether there was an association between birth experience and subsequent maternal care-giving attitudes and behavior over a 12-month period  5. Case control study In this study there are two groups of people: one has a health issue (Case group), and this group is “matched” to a Control group without the health issue based on characteristics like age, gender, occupation these studies estimate the odds between the exposure and the health outcome, however they cannot prove causality. Case-Control studies might also be referred to as retrospective or case-referent studies. Advantages: Limitations: - Helps you find the source of an existing - Patient recall about their history can be illness or epidemic. inaccurate (recall bias). - Cheap and quick to conduct this type of - Patients aware of certain risk factors may study. focus on those and ignore other exposures. - The health issue has already occurred, - No randomization is possible, lowering you don’t need a lab or special internal validity of the study. equipment. - Finding a Control group that matches the Case - Few ethics issues as the patient already group appropriately can be difficult. has the health condition - This study type does not prove a clear causal - Looks at multiple risk factors in a relationship between risk factors and illness, patient’s life (environment, work, diet). only calculates the odds. Thank you