Descriptive Study.pptx IN RESEARCH METHODS
- 1. DESCRIPTIVE STUDIES Dr.Anand K.Madgundi Assistant Professor Rachana Sharir Department S.G.R.Ayurved College,Solapur
- 2. LEARNING OUTCOME • What is study design • Types of study design • Descriptive study Case report Case series Cross sectional Study
- 3. WHAT IS STUDY DESIGN ? A study design is a specific plan or protocol for conducting the study, which allows the investigator to translate the conceptual hypothesis into operational one.
- 6. TYPES OF STUDIES Observational Investigator has no control over major independent or predictor variables Existing phenomenon used No intervention Experimental Investigator has control over major independent and predictor variables Study tests the effect of intervention on certain aspect of health or disease
- 7. EPIDEMIOLOGICAL METHODS 1) Observational studies : a. Descriptive studies b. Analytical studies i) Ecological or co relational ii) Cross-sectional or prevalence iii) Case – control iv) Cohort 2) Experimental studies : a. Randomized controlled trials b. Field trials c. Community trials
- 8. DESCRIPTIVE STUDIES Descriptive study is the first phase of epidemiological investigation. Observing the distribution of disease or health related events in human population. Identify the characteristics with which the disease is associated. Basically 3 questions are asked WHEN, WHERE AND WHO i.e. Time, place and person distribution.
- 9. TYPES OF DESCRIPTIVE STUDIES Case reports Case series Cross-sectional study
- 10. CHARACTERISTICS OF DESCRIPTIVE STUDIES Only one group (sample), no comparison group No preformed hypothesis regarding association Objective: Describe the disease/ phenomenon in persons, places and time Measures studied: Mean, proportion, rates Research question descriptive
- 11. PURPOSE/ WHEN TO CONDUCT? To describe Natural History of disease To know magnitude, trend of disease To describe certain health related variables To describe the occurrence of interesting episode Planning & evaluation To get some clues about cause
- 12. CASE REPORTS Detailed presentation of a single case. Generally report a new or unique finding ✓e.g. previous undescribed disease ✓e.g. unexpected link between diseases ✓e.g. unexpected new therapeutic effect ✓e.g. adverse events
- 14. HOW TO WRITE CASE REPORT Case reports should encompass the following five sections: 1. an abstract, 2. an introduction with a literature review, 3. a description of the case report, 4. a discussion that includes a detailed explanation of the literature review, and 5. a brief summary of the case and a conclusion.
- 15. Advantages Useful for hypothesis generation Informative for very rare disease with few established risk factors To generate a hypothesis about pathophysiological mechanism Just your fellow clinicians to be aware that they may come across this type of clinical manifestation during their clinical practice. Limitations Cannot study cause and effect relationships Cannot assess disease frequency
- 16. CASE SERIES Case series is a step ahead of case report, wherein you study a relatively larger group of patients who have a particular disease for example, you may study 10 or more patients with some rare type of cancer or with some rare type of tuberculosis or any other disease Experience of a group of patients with a similar diagnosis Cases may be identified from a single or multiple sources Generally report on new/unique condition
- 18. WHEN WRITING A CASE SERIES STUDY, THERE ARE SEVERAL KEY STEPS. • Decide which type of case report you'll be writing. • Choose a suitable publication for submission. • Case study report format. • Start writing. • Accumulate Case-Related Data. • Conclusion
- 19. Advantages • Useful for hypothesis generation • Informative for very rare disease with few established risk factors • Characterizes averages for disorder • It helps you to understand whether these kind of findings that they are observing, are they really due to the disease or is it due to the chance. • It may help you understand or develop what would be the clinical picture of patients presenting with a particular type of disease. Disadvantages • Cannot study cause and effect relationships • Cannot assess disease frequency
- 20. USES OF CASE REPORT & CASE SERIES Hypothesis generation Suggesting associations
- 21. Case Report One case of unusual findings Case Series Multiple cases of findings
- 22. CROSS-SECTIONAL STUDY A cross-sectional study (also known as prevalence study) is a type of observational study that involves the analysis of data collected from a population, at one specific point in time. Cross-sectional studies are most familiar to us as surveys Data collected at a single point in time
- 23. CROSS-SECTIONAL STUDY An "observational" design that surveys exposures and disease status at a single point in time (a cross-section of the population) Describes associations Prevalence A "Snapshot"
- 25. ADVANTAGES OF CROSS SECTIONAL STUDY Fairly quick and easy to perform Less expensive Extremely useful to know the magnitude, means how big the problem is
- 26. LIMITATIONS OF CROSS SECTIONAL STUDY Not useful to study disease etiology Not suitable for the study of rare diseases Major limitation Prevalent cases (Old and new cases) Exposure and outcome measured at the same time. Eg.Diabetes and obesity
- 27. USES OF CROSS SECTIONAL STUDY Estimate prevalence of disease or their risk factors Distribution of health problem by time, place and person Plan health care services delivery Set priorities for disease control Generate hypotheses Examine evolving trends - Before / after surveys
- 28. EXAMPLES OF RESEARCH QUESTIONS TO BE ADDRESSED THROUGH CROSS S ECTIONALSTUDY What is the prevalence of hypertension in a city? How satisfied are patients attending government hospitals in Chennai? What is the prevalence of physical inactivity among school children?
- 29. WRITING OF CROSS SECTIONAL STUDY Step 1: Identification of the Research Problem. ... Step 2: Recruitment of Participants on the Basis of Inclusion & Exclusion Criteria. ... Step 3: Data Collection. ... Step 4: Data Analysis. ... Step 5: Estimation of Prevalence. ... Step 6: Computation of Odd Ratio. Step 7 Inference of Correlation Step 8 Report Writing
- 30. ECOLOGICAL STUDY This is a study that you do for groups, that you can do at a country level, you can do for populations, you can do a particular region of the country and you try to understand a particular problem for a group and you try to relate problem as well as, what could be the possible reason, why that problem is occurring also at the group level. So in this type of study, group is the unit of analysis.
- 31. PROSTATE CANCER MORTALITY VERSUS SUGAR CONSUMPTION IN 71 COUNTRIES STUDIED • Per-capita sugar consumption is an ecological variable because it is the average measure of exposure to sugar for all the people in the country. It does not mean that every person in the country ate exactly the same amount of sugar. • Similarly, the mortality rate is a group-level variable because it represents the country's experience, not any individual person's experience in the country.
- 32. ADVANTAGES You are able to look at a particular population • Weaker inference, but easier to gather data • We can generate hypotheses for case-control studies and environmental studies • We can target high-risk populations, time-periods, or geographic regions for future studies
- 33. LIMITATIONS • Because data are for groups, we cannot link disease and exposure in individual • We cannot control for potential confounders • Data represent average exposures rather than individual exposures, so we cannot determine a dose- response relationship • Caution must be taken to avoid drawing inappropriate conclusions, or ecological fallacy ("The bias that may occur because an association observed between variables on aggregate levels does no necessarily represent the association that exists at the individual level.“)
- 34. EXAMPLES 1. How many people in the community have high blood pleasure? 2. Brucellosis: a rare cause of the unstable spine 3. In 1 hospital, a subset of patients hospitalized with Escherichia coli-induced hemolytic-uremic syndrome (HUS) developed neurologic symptoms during their stay 4. RA: a case report 5. An average intake of fat among people living in a state of Tamil Nadu
- 35. REFERENCES Park's Textbook of Preventive And Social Medicine, K. PARK. 23rd EDN Oxford Textbook of Public Health Vol 2. The Methods of Public Health. Fifth Edn. Detels, Beaglehole, Lansang. Gulliford. Essentials of Public Health Dentistry (Community Dentistry), Soben Peter. 5th EDN Essentials of Dental Public Health. Daly, Batchelor, Treasure,Watt. 2nd EDN http://annals.org/article.aspx?articleid=745807 http://www.consort-statement.org/consort-statement/flowDiagram http://www.ebbp.org/course_outlines/randomized_controlled_t rials/ http://medical dictionary.thefreedictionary.com/equivalence+trial
- 36. TAKE HOME MESSAGES Case reports and case series are useful for uncommon clinical manifestations Cross sectional surveys help to measure the burden or magnitude of health condition
- 37. THANK YOU