Epi Questions with 100%correct answers.

Epi Questions with 100%correct answers.Which of the following are examples of a population prevalence rate? A) The number of ear infections suffered by 3-year-old children in March, 2006 B) The number of persons with hypertension per 100,000 population C) The number of cases of skin cancer diagnosed in a dermatology clinic D) b and c E) All of the above -answerB) The number of persons with hypertension per 100,000 population Explanation: Prevalence is the number of affected persons in a specified population size at a given time. Only answer (b) fits this definition. Example (a) is more consistent with an incident rate while answer (c) is a selected group of persons who may not be representative of a general population. What would be the effect on age-specific incidence rates of uterine cancer if women with hysterectomies were excluded from the denominator of incidence calculations assuming that most women who have had hysterectomies are older than 50 years of age. A) The rates in all age groups would remain the same. B) Only rates in women older than 50 years of age would tend to decrease. C) Rates in women younger than 50 years would increase compared to women older than 50 years of age. D) Rates would increase in women older than 50 years of age but may decrease in younger women as they get older. E) It cannot be determined whether the rates would increase or decrease. -answerD) Rates would increase in women older than 50 years of age but may decrease in younger women as they get older. Explanation: Women who have had hysterectomies (i.e., removal of the uterus) are no longer at risk for uterine cancer. For women older than 50 years of age, this would increase the age-specific incidence rate as there would be the same number of uterine cancers occurring among fewer women at risk. Further, rates may decrease among younger women who have had hysterectomies as they are no longer at risk for uterine cancer and thus may decrease the number of potential cases occurring in their age group over time. A prevalence survey conducted from January 1 through December 31, 2003 identified 580 new cases of tuberculosis in a city of 2 million persons. The incidence rate of tuberculosis in this population has historically been 1 per 4,000 persons each year. What is the incident rate of tuberculosis per 100,000 persons in 2003? -answerThe answer is 29 new cases of tuberculosis per 100,000 persons. This is found by dividing the new cases of tuberculosis by the total population at risk (580/2,000,000) and multiplying this rate by 100,000 to standardize the rate. A prevalence survey conducted from January 1 through December 31, 2003 identified 580 new cases of tuberculosis in a city of 2 million persons. The incidence rate of tuberculosis in this population has historically been 1 per 4,000 persons each year. Has the risk of tuberculosis increased or decreased during 2003? -answerThe risk of tuberculosis has increased over the historic incident rate. This comparison can be made by standardizing the historic rate to a rate per 100,000 persons. To do this, multiply the numerator and denominator by 25. Which of the following is an advantage of active surveillance? A) Requires less project staff B) Is relatively inexpensive to employ C) More accurate due to reduced reporting burden for health care providers D) Relies on different disease definitions to account for all cases E) Reporting systems can be developed quickly -answerC) More accurate due to reduced reporting burden for health care providers Explanation: Active surveillance entails a concerted effort to collect information about disease occurrence. It typically involves dedicated staff members who have been specifically directed to contact physicians and hospitals in order to collect reports of disease cases in a specified population. This activity requires a large amount of staff and resources in order to accomplish its goals. The population of a city on February 15, 2005, was 36,600. The city has a passive surveillance system that collects hospital and private physician reports of influenza cases every month. During the period between January 1 and April 1, 2005, 2,200 new cases of influenza occurred in the city. Of these cases, 775 persons were ill with influenza according to surveillance reports on April 1, 2005. The monthly incidence rate of active cases of influenza for the 3-month period was: -answerC) 20 per 1,000 population Explanation: The monthly incidence rate is calculated based on the number of new cases of a disease developing during the 3-month time period. In this example, 2,200 cases of influenza developed among an average population of 36,600 persons at risk during the surveillance period. The incidence rate equals 2,200 divided by 36,600. In order to calculate the average monthly rate, the rate should then be divided by 3. Fin