PREP - Intro to Epidemiology 2

**[Core Principles of Mental Health Research]** **[PREP: Intro to Epidemiology 2]** [Study Designs:] - Observational vs Experimental (choice of study design will depend on whether the investigator assigned the exposure [Descriptive Epidemiology: Cross-sectional studies] - Conducted on i...

**[Core Principles of Mental Health Research]** **[PREP: Intro to Epidemiology 2]** [Study Designs:] - Observational vs Experimental (choice of study design will depend on whether the investigator assigned the exposure [Descriptive Epidemiology: Cross-sectional studies] - Conducted on individuals - Exposure & outcome status ascertained at a "cross-sectional" point in time - Often survey based i.e., questionnaire - Chiefly concerned with assessing frequency of disease occurrence - i.e., prevalence - and distribution i.e., by sex, age, race, social class - less useful for determinants of health [Strengths & Limitations] [Descriptive Epidemiology: Ecological Studies] - Conducted on populations - Disease frequencies compared between different groups in same period - Or, in the same population at different times - Often use routine data - Can reveal patterns at the population level - As before, limited in terms of determinants [Strengths & Limitations] [Analytical Epidemiology: Case-Control Studies ] - Conducted at the individual level - Starting point is case status - Identification of people with the disease outcome i.e., cases - A sample of controls (without the disease) are recruited & compared with respect to exposure of interest [Strengths & Limitations] [Analytical Epidemiology: Cohort Studies] - A population is identified without the disease outcome - Risk factors measured at points during follow up - Followed over time to see who develops disease [Strengths & Limitations] [Intervention Studies: Randomised Controlled Trials ] - A form of prospective cohort study - People identified based on exposure status & followed to see who experiences outcome - What is the major strength of a randomised trial? - Random allocation to exposure will, on average, ensure balance of other factors which could affect disease risk [Summary:] - No study design is optimal, all have strengths & weaknesses - Is some circumstances only certain designs will be possible? - In terms of casual inference: - RCT Very Strong - Cohort Study Moderate/Quite Strong - Case-Control Moderate - Cross-Sectional Weak - Ecological Very Weak