EPBI 5101 Homework #4 Name: TUID: Homework #4: Cohort Studies A researcher conducted a well-funded, prospective cohort study in 2011, in which she collected data on a total of 450 women who worked at Abrutze Radiology' in Houston, TX. After two years of follow-up, the researcher found that 80% of the Abrutze workers had received accidental low doses of radiation. Of the 80% of women who received the accidental low doses, 45% developed an aggressive form of uterine cancer within the two years. Of those women who did not receive the accidental radiation, 25 still went on to develop uterine cancer. 1. Construct a 2x2 table for this study. Clearly identify the exposure and outcome. (3 points) Total Total 2. Calculate the cumulative incidence rate per 1,000 people for the exposed group. (round to whole number) 3. Calculate the cumulative incidence rate per 1,000 people for the unexposed group. (round to whole number) 4. Calculate the Relative Risk comparing exposed to unexposed. (round to 2 decimals) 5. Is the exposure a risk factor or a protective factor? a. Risk factor b. Protective factor 1 Abrutze Radiology is a fictitious name. 1EPBI 5101 Homework #4 6. Provide a 1-sentence interpretation for the Relative Risk you calculated in question 4. 7. Describe one strength of the Abrutze Radiology cohort study. Make sure these are not general statements; they must relate directly to the Abrutze Radiology cohort study: 8. Describe one limitation of the Abrutze Radiology cohort study. Make sure these are not general statements; they must relate directly to the Abrutze Radiology cohort study: 2Formula Sheet Cumulative Inddence: Number of new cases of disease Risk/Rate Difference (Attributable Risk): Number in at-risk population Rate in exposed - Rate in unexposed Incidence Rate: Population Risk Difference (Population Attributable Risk): Number of new cases of disease Rate in total population - Rate in unexposed Person-time of observation in at-risk population Attributable proportion among the exposed: Point Prevalence: (Rate in exposed group - Rate in unexposed group] x 100 Number of existing cases of disease Rate in exposed group Number in total population (At a point in time) Alternative calc-> [RR-1) X 100 AR Perlod Prevalence: Number of existing cases of disease Population Attributable Risk Percent (Attributable proportion In Number in total population the total population) [ During a period of time) (Rate in total population - Rate in unexposed population] * 100 Rate in total population Crude Mortality Rate: Number of death * 100,000 Alternative calc > P[BR - 1) X 100 Number of people in total population [P [RR - 1) + 1] Where P is the exposed proportion in either the study or general Case-Fatality Rate: population Number of people dying from disease X x 100 Number of people with the disease X Sensluvity = True positives / Total with disease= a/(a+c) Specificity = True negatives / Total without disease= d/(d+b] Proportionate Mortality Rate: Number of deaths from disease X x 100 PPV = True positives / Total tested positive= a/[a+b) Total number deaths from all diseases NPV = True negatives / Total tested negative= d/[c+d) Age-Specific Mortality Rate: Number of deaths in a given age group * 100,000 Total number of people in the age group Cause-Specific Mortality Rate: Number of deaths from a given cause x 100,000 Total number of people in the population RR = Rate in exposed = A/(A+B) + C/[C+D) Rate in unexposed OR: Odds of exposure among cases Odds of exposure among controls = [A/B) + (C/D) = AD/BC = [A/C] + (B/D)