Midterm Exam Review

Midterm Exam Review BMTRY 736 Foundation of Epidemiology Fall 2019

Review • Measures of disease frequency • Prevalence • Cumulative incidence • Incidence and mortality rates • Age-standardization • Attributable risk • 2x2 tables

Question 1 1. A prevalence survey was conducted from January 1 through December 31, 2003 in a city of 2 million persons. On January 1, 2003, 995 people reported that they had schizophrenia. By August 1, 2003, 3 people in the population had developed schizophrenia. At the end of the study in December, 5 new cases in total had been reported over the course of the year. a) How many new cases of schizophrenia developed between August 1, 2003 and December 31, 2003 in this population? b) What was the cumulative incidence of schizophrenia on August 1, 2003? (per 100,000) c) What was the cumulative incidence of schizophrenia for the year on December 31, 2003? (per 100,000) d) What was the prevalence of schizophrenia on January 1, 2003? (per 100,000) e) What was the prevalence of schizophrenia on December 31, 2003? (per 100,000)

Question 2 2. What would be the effect on age-specific incidence rates for uterine cancer if women with hysterectomies were excluded from the denominator of calculations, assuming that there are some women in each age group who have had hysterectomies? • a. the rates would remain the same • b. the rates would tend to decrease • c. the rates would tend to increase • d. the rates would increase in older groups and decrease in younger groups • e. it cannot be determined whether the rates would increase or decrease

Question 3 3. Use the table below to calculate the crude death rate as well as age-specific death rates per 1,000 population in the Florida county of Leon in 1988. Table 1: Leon County, 1988 • Calculate and fill in age-specific death rate per 1,000 column. in table 1. • Assume that you wish to standardize to the hypothetical population above. Fill in the age-adjusted death rate per 1,000 column in table 1.

Question 6 For questions 6 and 7, use the information below: • Population of the city of Atlantis on March 30, 2003 = 183,000 • No. of new active cases of TB occurring between January 1 and June 30, 2003 = 26 • No. of active TB cases according to the city register on January 1, 2003 = 264 6. The cumulative incidence of active cases of TB for the 6-month period was: • a. 7 per 100,000 population • b. 14 per 100,000 population • c. 26 per 100,000 population • d. 28 per 100,000 population • e. 130 per 100,000 population

Question 7 For questions 6 and 7, use the information below: • Population of the city of Atlantis on March 30, 2003 = 183,000 • No. of new active cases of TB occurring between January 1 and June 30, 2003 = 26 • No. of active TB cases according to the city register on January 1, 2003 = 264 7. The prevalence of active TB as of June 30, 2003, was: a. 14 per 100,000 population b. 130 per 100,000 population c. 158 per 100,000 population d. 264 per 100,000 population e. none of the above

Question 8 8. In an Asian country with a population of 6 million people, 60,000 deaths occurred during the year ending December 31, 1995. These included 30,000 deaths from cholera in 100,000 people who were sick with cholera. • What was the cause-specific mortality rate from cholera in 1995? (per 100,000) • Calculate and interpret the case-fatality rate from cholera in 1995? (Please portray as a percent)

Question 9 and 10 Refer to table 2 to answer questions 9-14 Table 2. Eating fish and stroke • Calculate cumulative incidence in exposed/those who never ate fish (per 1000) • Calculate cumulative incidence in the unexposed/those who ate fish almost daily (per 1000)

Question 11 and 12 Refer to table 2 to answer questions 9-14 Table 2. Eating fish and stroke • Calculate and interpret attributable risk (per 1000) • Calculate and interpret attributable risk proportion (per 1000)

Question 13 Refer to table 2 to answer questions 9-14 Table 2. Eating fish and stroke • Calculate and interpret population attributable risk (per 1000)

Question 14 Refer to table 2 to answer questions 9-14 Table 2. Eating fish and stroke • Calculate and interpret population attributable risk percent (also known as the population attributable proportion)

Question 15 15. For a disease such as pancreatic cancer, which is highly fatal and of short duration: • a. Incidence rates and mortality rates will be similar • b. Mortality rates will be much higher than incidence rates • c. Incidence rates will be much higher than mortality rates • d. Incidence rates will be unrelated to mortality rates • e. None of the above

Question 16 16. Which of the following is a good index of the severity of a short-term, acute disease? • a. Cause-specific death rate • b. 5-year survival • c. Case-fatality rate • d. Standardized mortality ratio • e. None of the above

Question 17 17. Of 2,872 persons who had received radiation treatment in childhood because of an enlarged thymus, cancer of the thyroid developed in 24 and a benign thyroid tumor developed in 52. A comparison group consisted of 5,055 children who had received no such treatment (brothers and sisters of the children who had received radiation treatment). During the follow-up period, none of the comparison group developed thyroid cancer, but benign thyroid tumors developed in 6. Fill in the 2x2 table below and use it to calculate the relative risk for benign thyroid tumors between the comparison and control groups.

Question 18 18. The results of a 10-year cohort study of smoking and coronary heart disease (CHD) are shown below: Calculate the incidence of CHD in smokers that can be attributed to smoking.

Question 19 19. What factors should be considered in measuring long-term changes in disease frequency over time? • a. Changes in diagnostic criteria • b. Changes in the age distribution • c. Changes in the fatal course of the condition • d. All of the above • e. None of the above

Question 20 20. The risk of acquiring a given disease during a time period is best determined by: • a. the mortality rate from that disease in the 0-4 age group. • b. a spot map that records all cases of the disease in the past year. • c. the period prevalence for that disease during the past year. • d. the incidence rate (cumulative incidence) for that disease in a given period of time. • e. the case fatality rate for the disease

Question 21 21. An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year: • Number of skaters in Metroville during any given month 12,000 • Roller-skating injuries in Metroville 600 • Total number of residents injured from roller-skating 1,800 • Total number of deaths from roller-skating 90 • Total number of deaths from all causes 900 a) The crude death rate for all causes was: • a. 90/600 × 100,000 • b. 900/100,000 × 100,000 • c. 90/1,800 × 100,000 • d. 90/900 × 100,000 • e. 600/10,000 x 100,000

Question 21 21. An epidemiologic survey of roller-skating injuries in Metroville, a city with a population of 100,000 (during the midpoint of the year), produced the following data for a particular year: • Number of skaters in Metroville during any given month 12,000 • Roller-skating injuries in Metroville 600 • Total number of residents injured from roller-skating 1,800 • Total number of deaths from roller-skating 90 • Total number of deaths from all causes 900 b) The cause-specific mortality rate from roller-skating was: • a. 90/600 × 100,000 • b. 90/100,000 × 100,000 • c. 90/1,800 × 100,000 • d. 90/900 × 100,000 • e. 600/10,000 x 100,000

Question 22 True or false questions 22. The crude death rate is defined as the number of deaths in a given year divided by a reference population (during mid-point of the year) multiplied by 100,000.

Question 23 True or false questions 23. The point prevalence of a disease is defined as the number of persons ill divided by the total number in the group at a point in time.

Question 24 True or false questions 24. The cumulative incidence of a disease is defined as the number of new cases of the disease over a time period divided by the total population (at risk) during the same time period times a multiplier (e.g. 100,000).

Question 25 True or false questions 25. When the duration of a disease becomes short and the incidence is high, the prevalence becomes similar to incidence.

Question 26 True or false questions 26. For a chronic disease of low incidence and long duration, prevalence of the disease increases relative to incidence.

Question 27 True or false questions 27. The incidence rate of a disease is defined as the number of new cases of the disease over the number of person years for the total population.

Question 28 True or false questions 28. At the initial examination in the Framingham study, coronary heart disease was found in 5 per 1000 men ages 30-44, and in 5 per 1000 women ages 30-44. The inference that in this age group men and women have an equal risk of getting coronary heart disease is correct (Bonus: Why or why not?)

Question 33 33. Identify what the exposure of interest is in this study

Question 33 34. Identify what the outcome of interest is in this study

Question 33 35. What is the population to which this study is generalizable?

Question 33 36. What is the study sample?

Midterm Exam Review