University:
Camosun College
Course:
BIOL 252 | Pathophysiology for Nursing 1
Academic year:

2024
Views:

185

Pages:

2
Author:

Aysha A.

Cohort Study Definition: A group of people followed together in the future. Example Group: 100 MBBS students 20 boys + 20 girls in a relationship. 20 boys + 20 girls single. Variables to Look For: Marks, addictions, hours of exercise, headaches. Followed for 6 months to observe changes in these variables. Example results: Headaches: 6 (relationship group) vs. 5 (single group). Pass marks: 30 (relationship group) vs. 32 (single group). Addictions: 30 (relationship group) vs. 20 (single group). Key Concepts Incidence: Refers to new cases. Incidence Rate: Calculated as the total new cases divided by the total time (cases/time). Cumulative Incidence: The total number of new cases divided by the total population in the study. Relative Risk (Risk Ratio): Best measure of the strength of association between exposure and outcome. Formula: Incidence in exposed / Incidence in non-exposed. Example given: 6/40 (exposed) vs. 5/40 (non-exposed). Additional Notes Cohort studies are beneficial in identifying: Temporality (sequence of events). Multiple outcomes. Risk ratios. However, they can be time-consuming and costly. Relative Risk (RR) Definition: RR is the ratio of the incidence of an outcome (like a disease or condition) in an exposed group to the incidence in a non-exposed group. Explanation: If RR is 1.2, for example, it means that the incidence of the outcome (like headaches) is 1.2 times higher in the exposed group (e.g., students in relationships) compared to the non-exposed group (e.g., single students). Example with Exercise and Relationship Status A table is used to display data for two groups based on their relationship status and whether they exercise for more than 4 hours: Relationship: Exercise > 4 hours: 𝑎 = 5 a=5 Exercise < 4 hours: 𝑏 = 35 b=35 Single: Exercise > 4 hours: 𝑐 = 10 c=10 Exercise < 4 hours: 𝑑 = 30 d=30 Calculation of RR: The formula is given by This formula calculates the relative risk by comparing the incidence rate in the exposed group to the incidence rate in the non-exposed group. Another Example with Alcoholic Drivers A similar table shows data for 100 alcoholic drivers and 100 non-alcoholic drivers, divided based on whether they were involved in an accident: Alcoholic Drivers: Accident: 20 No accident: 80 Non-Alcoholic Drivers: Accident: 5 No accident: 95 Calculation of RR: Using the formula In this example, the relative risk for accidents among alcoholic drivers compared to non-alcoholic drivers is calculated as 4, indicating that alcoholic drivers are 4 times more likely to be involved in an accident. Summary These notes provide a practical explanation of how relative risk is calculated using simple tables, with examples illustrating the application in different scenarios. The RR value helps in understanding the strength of association between an exposure and an outcome.