Computer generated transcript

Warning!
The following transcript was generated automatically from the content and has not been checked or corrected manually.

Study Designs By: Agi Jothi (MBChB 5) Presentation layout What are study designs? Why is it important to have knowledge about study desings Types of study designs What are study designs? • Framework • Set of methods • Procedures • collect data • Analyse data Why are study designs important? • High quality research • sets boundaries • Prevents blind search • Validity of resultsLevel of evidence Types of study designs • Descriptive studies (describe features of a population) • Case report • Case series • Analytical studies • Observational (no controlled intervention) • Cross-sectional study • Case-control study • Cohort study • Experimental (manipulate treatment/exposure) • Randomized controlled trials • Clinical trials • Animal trials • Cross over trials • N-of-1 trials Key terminologies • Longitudinal : dealing with • Cross-sectional: dealing with patients at > 1 point in time (i.e. patients at 1 point in time seen over days, months, years) • Retrospective: dealing with patients • Prospective: dealing with patients present and past with pre-existing in the present and future data • Explanatory: study taking place in • Pragmatic: study taking place in ideal settings; usually intervention ordinary settings; usually vs placebo; produces efficacy intervention vs standard of care; data produces effectiveness data and reflects everyday practice Case Report • Type of an observational study • Involves a single patient (n=1) • Usually not a repeated report • Prone to chance association and bias Case Series • Type of an observational study • Involves a group of patients • Useful for studying rare disease Cohort Study • Type of observational study • Involves groups • Cohort exposed to risk vs cohort not exposed to risk • Followed up to see who develops the condition (good quality records) • Prospective or follow-up study • Can measure incidence • Long time (has temporality) • Expensive • Attrition risk (drop out) Case-Control Study • Patients with a certain outcome (cases) are matched with patients without the outcome (control) • Look back to identify exposure risks (retrospective) • Useful to investigate new diseases / rare diseases • Quick • Cheap • Recall bias • Cant estimate prevalence and incidence • Eg. Group with breast cancer and without breast cancer. Participants are questioned about risk factors Cross-Sectional Study • Type of observational study • Snapshot of a population • Compare many different variables at the same time • Can estimate prevalence • Does not determine cause and effect relationship • No follow up needed • Cheap and quick collection of data • Lacks temporality (time component) Randomised Controlled Trial (RCT) • Type of experimental study • Patients randomized to treatment arm and control arm • Requires ethical approval • Difficult • Time consuming • Expensive • Gold standard for studying effectiveness of treament. Crossover trial • participants do not only receive one intervention, but multiple, and the effect of the interventions are measured on the same individuals • Sequence of interventions (switch) • Requires a washout period • Assess which treatment works better • Useful when there is a lack of patients N-of 1 Trial • Type of crossover trial • Single subject • investigating the efficacy or side- effect profiles of different interventions • Useful for determining what works best for the patient • Requires a long time Audit • measuring a clinical outcome or a process, against well-defined standards set on the principles of evidence-based medicine in order to identify the changes needed to improve the quality of care. • Audit cycle: minimum 2 • Ethical approval not necessarily needed • Lots of data collection and time consuming Systematic Review & Meta-Analysis • Highest level of evidence • Systematic review • a summary of the medical literature that uses explicit and reproducible methods to systematically search, critically appraise, and synthesize on a specific issue. • Meta-analysis • quantitative, formal, epidemiological study design used to systematically assess the results of previous research to derive conclusions about that body of research. Conclusion • Study designs are a framework that has a set of methods to collect data • Important for high-quality research • The type of study design depends on the type of outcome • Observational vs experimental studiesEmail add: 2296404a@student.gla.ac.uk Next session • 22/10/22 (Saturday at 10:30-11:30 am BST) • Critical appraisal of a quantitative research paper • Why • How • Example