Observational Studies Lecture Notes PDF

Lesson 12 Observational studies Biostatistics, Epidemiology and Public Health Prof. Eugenia García Zaragozá, PhD Bachelor in Dentistry ACADEMIC YEAR 2023-2024 ÍNDICE TABLE OF CONTENTS CONTENIDOS Non-experimental Studies Descriptive 1. Ecologic Studies 2. Cross-Sectional Studies 3. Case reports...

Lesson 12 Observational studies Biostatistics, Epidemiology and Public Health Prof. Eugenia García Zaragozá, PhD Bachelor in Dentistry ACADEMIC YEAR 2023-2024 ÍNDICE TABLE OF CONTENTS CONTENIDOS Non-experimental Studies Descriptive 1. Ecologic Studies 2. Cross-Sectional Studies 3. Case reports / Case series Analytical 4. Cohort Studies 5. Case-control Studies 2 Types of studies in Epidemiology 3 1. Ecological studies: Generalities 4 1. Ecological studies: Generalities 5 1. Ecological studies: 6 1. Ecological studies: 7 1. Ecological studies: Ecological fallacy 8 1. Ecological studies: Ecological fallacy 9 1. Ecological studies: Literacy rate and Native American origin study in 48 U.S. states in 1930 by Robinson: POPULATION-LEVEL OBSERVATION: CONCLUSION: Non-native "blacks" have. higher literacy rates than natives. OBSERVATION AT THE INDIVIDUAL LEVEL: In areas where natives are more literate there are higher % of non-native "black" residents (illiterate). 10 1. Ecological studies: Ecological fallacy 11 1. Ecological studies: ADVANTAGES DISADVANTAGES Information is usually available They cannot establish a causal (demographic data, mortality relationship between a disease and an registries, cancer registries, etc.). exposure at the individual level. ECOLOGICAL FALACY: Drawing inappropriate conclusions at the individual level based on population data. Easy and fast to perform Not able to control confounding variables. potentially Low cost 12 Types of studies in Epidemiology 13 2. Cross-Sectional studies (Prevalence studies): Generalities Cross-sectional study about the use of glasses among schoolaged children 14 Generalities -number of children wearing glasses -vegetable intake habits 15 2. Cross-Sectional studies: Types Reverse causality 16 Measures ………..not incidence 17 2. Cross-Sectional studies: Measures: prevalence ratio 18 Types of studies in Epidemiology 19 3. Case report / Case series: Key issues • Timeless description of a case or a reduced number of cases, with common features • New diseases or new adverse (epidemiological surveillance). effects 20 Types of studies in Epidemiology 21 4. Cohort studies: Generalities 22 4. Cohort studies: Measures Example: Cohort study to determine whether smoking is a risk factor for developing lung cancer FOLLOW-UP 20 years SMOKERS NON-SMOKERS Lung cancer NO Lung cancer Healthy adults Murcia 23 4. Cohort studies: Measures 24 4. Cohort studies: Measures 25 4. Cohort studies: Key issues 26 5. Case-control studies: Generalities 27 5. Case-control studies: Measures Healthy adults Murcia Example: Case-control study to determine whether smoking is a risk factor for developing lung cancer SMOKERS LUNG CANCER NON-SMOKERS SMOKERS NON-SMOKERS NO LUNG CANCER RESEARCH 28 5. Case-control studies: Measures 29 30 5. Case-control studies: Measures the only statistical measure we can use in case-control studies is the odds ratio 31 5. Case-control studies: Key issues 32 5. Case-control Studies: Types 33 Case-control vs. Cohort studies https://www.youtube.com/watch?v=Jd3gFT0-C4s 34 35 Remember ❑ ❑ ❑ ❑ ❑ ❑ OBSERVATIONAL STUDIES observe events as they happen, without interfering with routine clinical practice. There is no random allocation of the intervention studied. They can be DESCRIPTIVE (only describe health of individuals and populations in terms of frequency, person, time and place) or ANALYTICAL (designed to draw inferences about health outcomes across different exposure groups) ECOLOGICAL STUDIES use averaged measures of the populations under study. CROSS-SECTIONAL Transverse description of the population. Descriptive or Analytical depending on their design. COHORT STUDIES Groups are made according to the exposition to a risk factor and then followed-up over time until they develop the disease. CASE-CONTROL STUDIES Subjects with the disease of interest are selected (cases) and their previous exposures to the risk factors investigated (retrospective design). 36 REFERENCIAS BIBLIOGRAPHY BIBLIOGRÁFICAS - Gordis L., Epidemiology, 4th Edition. 2009. Saunders Elsevier -Somerville M., Kumaran K., Anderson R. Public Health and Epidemiology at a Glance, First Edition. 2012. John Wiley & Sons, Ltd - Deter R., Gulliford M., Karim Q.A, Tam C.C. Global Public Health. Sixth Edition. Oxford University Press. 2015 37 Prof. Eugenia García Zaragozá, PhD [email protected] UCAM Universidad Católica de Murcia © © UCAM UCAM