TOPIC: Bio Statistics + Health Care
DESCRIPTION:
Please do not take if you do not know. RATIONALA for each question Total points=50 (20% of the course grade) 1. Which of the following research question we can use case-control study to answer? [ONE POINT] a. What is the past mortality or morbidity trends that can help estimates of the occurrence of disease in the future? b. What is the relative frequency of the characteristic or exposure under study when you compare histories and other information from a group of cases and from a comparison group? c. What is the possibility to analyze previous research in different places and under different circumstances to establish hypotheses based on cumulative knowledge of all known factors? d. What is the incidence of cancer in men who have quit smoking? e. None of the above
a. Past mortality or morbidity trends can help estimates of the occurrence of disease in the future because they can provide information about how common a disease has been over time. This can help to identify patterns and trends that may be useful in predicting future trends.
b. The relative frequency of a characteristic or exposure is the ratio of the number of cases with the characteristic or exposure to the total number of cases. When you compare this frequency between a group of cases and a comparison group, you can determine whether the characteristic or exposure is more common in one group than the other.
c. Analyzing previous research from different places and under different circumstances can help to establish hypotheses based on cumulative knowledge of all known factors. By considering a wide range of research, you can identify patterns and trends that may not be evident in any one study alone.
d. The incidence of cancer in men who have quit smoking can be determined by comparing the number of men who have quit smoking and subsequently developed cancer to the number of men who have never smoked or who continue to smoke. This can provide information about the potential protective effect of quitting smoking on cancer risk.
2. In a study of a disease in which all cases that developed were ascertained, if the relative risk (RR) for the association between a factor and the disease is as follows: Interpret the relative risk (RR) for each of the following RR and give example: a. Equal to 1 [ONE POINT] : b. Below 1 [ONE POINT] : c. <= 1 [ONE POINT] : 3. Researchers select 100 patients with colon cancer and 300 patients without colon cancer. Of the 100 patients with colon cancer, 15 smoke cigars while 40 of the 300 patients without colon cancer smoke cigars. a. What is the study design of this study? [ONE POINT] b. Calculate and interpret the measure of association between colon cancer and cigar smoking. Show your work. [ONE POINT] 4. In a study of a disease in which all cases that developed were ascertained, if the relative risk for the association between a factor and the disease is equal to 1.0, then (Select the best answer): [ONE POINT] a. The study design used is case-control design b. The study design used is cohort design c. Either matching or randomization has been unsuccessful d. The comparison group used was unsuitable, and a valid comparison is not possible e. None of the above 5. A random sample of middle age sedentary males was selected from six census tracts, and each man was examined for hypertension. All those having the hypertension disease were excluded from the study. All others were randomly assigned to either a diet/exercise group, which followed for a three-year program of systematic exercise, or to a group which had no diet/exercise program. Both groups were observed semiannually for any difference in incidence of hypertension. • What type of study design you would assign to this information? Why? [ONE POINT] • What will be the measure of association that you will use in this study? [ONE POINT] 6. Several studies have found that approximately 80% of cases of lung cancer are due to asbestos exposure. a. What is the name of this measure? [ONE POINT] b. Interpret the measure you selected? [ONE POINT] 7. Complete the Table 1 (Table below) by calculating the polio incidence rates, disease-specific mortality rates, and case-fatality for each of the past five years. Interpret the data and the trend over time. [THREE POINTS] Table 1. Incidence, mortality and case fatality. # New Midyear Incidence Mortality Case-fatality Year Cases # Deaths Population per 100,000 per 100,000 (%) 1986 45 5 340,000 1987 62 11 353,680 1988 49 10 397,880 1989 82 14 442,620 1990 90 18 433,920 Questions 8 and 9 refer to the following information: OUTCOME AFTER 10 YRS At Beginning of Study CHD Developed CHD Did Not Develop 2,000 Healthy smokers 200 1,800 4,000 Healthy nonsmokers 70 3,930 The results of a 10-year cohort study of smoking and coronary heart disease (CHD) are shown above: 8. The incidence of CHD in smokers that can be attributed to smoking is: [ONE POINT] 9. The proportion of the total incidence of CHD in smokers that is attributable to smoking is: [ONE POINT] 10. Discuss the types of study design that can be used in assessing causality? Which one is the gold standard? [TWO POINTS] 11. To study the relationship between oral contraceptive (OC) use and ovarian cancer, CDC initiated a study – the Cancer and Steroid Hormone Study. Case-patients were enrolled through eight regional cancer registries participating in the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute. a. What type of design is this study? Where they can get the comparison group? [ONE POINT] b. What types of bias are of particular concern in this study? [ONE POINT] c. What steps might you take to minimize these potential biases in this study? [ONE POINT] d. The primary purpose of this study was to measure and test the association between OC use and Ovarian cancer. The data are shown in Table 2 below. From these data in table 2, calculate the risk of ovarian cancer among oral contraceptive users? Explain [ONE POINT] Table 2. Ever-use of oral contraceptives among study groups SEER Cases Comparison group Ever 99 959 Never 80 683 Total 179 1642 e. Discuss under what circumstances would age be a confounder in this study? [ONE POINT] f. Discuss the approach(s) to handling confounding? [ONE POINT] 12. Discuss effect modification and explain how do you look for effect modification in a study? How do you handle the effect modifier in the analysis? [ONE POINT] 13. Discuss the important criteria that you can use to determine causal inferences? Give example [TWO POINTS] 14. Which of the following are advantage(s) of a prospective cohort study? [select all that apply] [ONE POINT] a. Precise measurement of exposure is possible b. Incidence rates can be calculated d. Recall bias is minimized compared with a case-control study c. It usually costs less than a case-control study e. Many disease outcomes can be studied simultaneously 15. Discuss the major problem resulting from the lack of randomization in a cohort study? [ONE POINT] 16. Residents of three villages with three different types of water supply were asked to participate in a survey to identify cholera carriers. Because several cholera deaths had occurred recently, virtually everyone present at the time underwent examination. The proportion of residents in each village who were carriers was computed and compared. Discuss what is the study design used in this study? [ONE POINT] 17. It has been suggested that physicians may examine women who use oral contraceptives more often or more thoroughly than women who do not. If so, and if an association is observed between phlebitis and oral contraceptive use, could this association be due to bias? what could be the type of bias in this study? [ONE POINT] Question 18 is based on the information given below: In a case-control study of the relationship of radiation exposure and thyroid cancer, 50 cases admitted for thyroid cancer and 100 “controls” admitted during the same period for treatment of hernias were studied. Only the cases were interviewed, and 20 of the cases were found to have been exposed to x-ray therapy in the past, based on the interviews and medical records. The controls were not interviewed, but a review of their hospital records when they were admitted for hernia surgery revealed that only 2 controls had been exposed to x-ray therapy in the past. 18. Based on the description given above, what source of bias is least likely to be present in this study? [ONE POINT] a. Recall bias b. Bias due to loss of subjects from the control group over time c. Bias due to controls being non-representative of the non-diseased population d. Bias due to use of different methods of ascertainment of exposure in the cases and controls e. Selection bias for exposure to x-ray therapy in the past 19. Data for the case-control study were obtained from hospitalized patients in London and vicinity over a 4-year period (April 1948 – February 1952). Initially, 20 hospitals, and later more, were asked to notify the investigators of all patients admitted with a new diagnosis of lung cancer. These patients were then interviewed concerning smoking habits, as were controls selected from patients with other disorders (primarily non-malignant) who were hospitalized in the same hospitals at the same time. The following table (table 3) shows the relationship between cigarette smoking and lung cancer among male cases and controls. Table 3. Smoking status, lung cancer cases and matched controls with other diseases. CASES CONTROLS SMOKERS 1340 1286 NON SMOKERS 17 71 TOTAL 1357 1357 a. Discuss how representative of all persons with lung cancer are hospitalized patients with lung cancer? [ONE POINT] b. Discuss how representative of the general population without lung cancer are hospitalized patients without lung cancer? [ONE POINT] c. Estimate the odds ratio from the data in table 3 (ABOVE) and interpret the odds ratio. [ONE POINT] 20. Data on 1075 male respondents to the 2003 Health Information National Trends Study were collected from October 2002 to April 2003 and analyzed in 2008 to examine the associations among race/ethnicity, and the perception of the risk of developing prostate cancer for African-American, Hispanic, and non-Hispanic white men aged ≥45 years without a history of prostate cancer. – What study design is been used for this study? Why? [ONE POINT] 21. Explain the relationship between specificity and false positive results? Give example (ONE POINT) 22. The figure below represented the number of cases of salmonella isolation by months of isolation. a. Discuss the steps for conducting an outbreak investigation for this disease. [TWO POINTS] 23. The figures (1, 2, and 3) below represented the epidemiologic curve for outbreak investigation. Discuss the type of source of the epidemic for each figure (ONE POINT). 24. The following table represents the results of a study to investigate an outbreak of gastroenteritis in California. Using the data in table 4 (the table below), complete the following: a. Attack rate (AR) for those who ate the specific identified food and those who did not eat these food [ONE POINT] b. The relative risk (RR) for each specific identified food [ONE POINT] c. Which food is the most likely cause of the outbreak? Why? [ONE POINT] d. What steps you will take after the identification of the source of outbreak? [ONE POINT] Table 4. results of a retrospective cohort study Food Ate Did not eat Ill well total AR Ill well total AR RR Meat 12 22 35 30 Spinach 35 5 10 22 Potato 10 43 10 30 Salad 20 6 10 37 Ice cream 2 28 2 19 25. What is the indicator that measures the extent to which a specific health care treatment, service, procedure, program, or other intervention produces a beneficial result under ideal controlled conditions? Give example [ONE POINT] 26. What serves as the basis for regulations affecting research by the U.S. government? [ONE POINT] a. The Nuremberg Code b. The Declaration of Helsinki c. The Belmont Report d. The Code of Ethics of the American Psychological Association 27. The purpose of a double blind or double masked study is to: [ONE POINT] a. Achieve comparability of treated and untreated subjects b. Avoid observer bias and sampling variation c. Avoid subject bias and sampling variation d. Reduce the effects of sampling variation e. Avoid observer and subject bias 28. Discuss the different types of screening programs. Give example of each type. [ONE POINT] 29. Discuss the different types of biases that can occur in a screening program. [ONE POINT] 30. In general, screening should be undertaken for diseases with specific feature(s). Select what feature(s) from the following list (select all that apply) : [ONE POINT] a. Diseases with a low prevalence in identifiable subgroups of the population b. Diseases for which case-fatality rates are low c. Diseases that are readily diagnosed and for which treatment efficacy has been shown to be equivocal in evidence from a number of clinical trials d. Diseases with a natural history that can be altered by medical intervention
