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Answers to the Quiz on Evidence Based Health (with answers) #

Q1. Which of the following activities is the best example of evidence based health practice?

Explanation: Evidence based health is essentially about critical appraisal, so this is a best example.

Q2. You have conducted a study on the association between weekly fast food consumption and prevalence of obesity among university students at the University of Canterbury (UC). Which of the following will limit the external validity of your study?

Q3. You conducted a study (N = 200) among patients admitted to the Christchurch hospital on the association between self-reported cigarette smoking status and heart disease; you found that smokers in your sample had higher risk of heart disease (Odds Ratio = 2.5) and the results were statistically significant (p < 0.001 and 95% Confidence Interval: 1.26 - 3.25). Which of the following statements is a limitation of the internal validity of your study?

Q4. Which of the following statements about the sample size for a study is correct?

Q5. You have conducted a double blind randomised controlled trial of a new antidepressant medicine, comparing with treatment as usual, on university students who were diagnosed with depression. You found that the new medicine had better outcomes than treatment as usual in controlling depression among university students (p = 0.002). Which of the following statements is correct about limitation of your study?

Q6. To investigate if wood splitting with heavy axe can lead to heart attacks (acute myocardial infarction, aka AMI), you conducted a case control study at a hospital with 200 patients who suffered heart attack (“cases”), and 200 patients who were admitted for some other conditions (“controls”). For “wood splitting with heavy axe” and AMI, you found Odds Ratio = 0.87, 95% Confidence Interval: 0.78 - 2.20. Which ONE of the following statements is true about this study?

Q7. A company advertised a new “turmeric tablet” in the market. In their advertisement, they showed a famous doctor who claimed that he tested the “turmeric tablets” twice daily on 200 arthritis patients who had severe pain & who were selected at random from his clinics; 150/200 (75%) patients reported that they were pain free after three months of treatment. the company claimed that their “turmeric” medication was effective treatment of arthritic pain. Which ONE of the following statements about this claim is CORRECT?

Q8. You are about to assess the evidence on the effectiveness of screening programmes for cervical cancer. Which of the following statements is CORRECT about systematically developing an evidence base?

Q9. You want to find out if smoking increases heart failure risk. You select 100 heart failure patients admitted to the local hospital and recruited 100 other patients in the same hospital but in different wards. You then took their histories of smoking. What kind of study did you conduct?

Q10. You are a health protection officer at a factory and you suspect some workers are exposed to mercury in the plant that results in nerve damage to these workers. You decide to study old health records of the workers and decide to follow them for the previous 10 years. You learn about workers who started working healthy, then got exposed to mercury in the plant and subsequently developed nerve disease. You also reviewed similar health records of clerks who worked in other sections of the factory and were never exposed to mercury, for comparison. What is your study design?

Q11. A rare disease is defined as one whose age-adjusted annual rate is less than 1 per 10, 000. Age-adjusted annual rate of the cancer of the pancreas is 11 per 100, 000 population. You want to find out if heavy alcohol consumption causes pancreatic cancer. Which of the following study designs is best suited for such a research?

Q12. You want to find out the prevalence of high blood pressure (“hypertension”) among university students in New Zealand. You invite all UC students to participate in the study and those who were willing to participate, you asked them to report to the UC health centre on the last day of the term for their blood pressures to be taken by a nurse. You will use the blood pressure measurements to estimate the prevalence of hypertension in university students. Which of the following best describes your study design?

Q13. You work at the Canterbury District health board and they want you to report all new cases of gastroenteritis in healthy adults in Canterbury between 2018-2019. What study design should you set up to report gastroenteritis cases in the district between 2018-2019?

Q14. You are testing a drug to treat high blood pressure and you are conducting a double blind randomised controlled trial. What of the following is correct about double blinding?

Q15. You want to study the effectiveness of lifestyle modification in prevention of heart disease. If you have to select one method to study the association, which of the following is MOST appropriate for you to consider when you select your methodology?

Q16. You have read a report that stated, “For men with heart disease and high cholesterol, use of the drug Lipicor as opposed to Placebo reduces the five-year chance of death from 9 percent to 5 percent”. What is the relative risk reduction (in % value) in reduction of heart disease related deaths if patients were to use Lipicor?

Q17. You have read a report that stated, “For men with heart disease and high cholesterol, use of the drug Lipicor as opposed to Placebo reduces the five-year chance of death from 9 percent to 5 percent”. Based on this data, how many people would have to be treated (NNT) with Lipicor in order to prevent death in one person?

Q18. The following figure shows association between exercise and serum cholesterol levels (X axis = hours of exercise, Y axis = serum cholesterol level). On the left hand side, data shown for the entire population, on the right hand side graph, the same graph is stratified for 10-yearly age groups. The two figures are same, except the regression lines are different. Which of the following statements is CORRECT?
[](cholesterol-exercise.png)

Q19. Which of the following study designs is best suited to study causes of rare diseases such as cancers?

Q20. You are testing the effectiveness of a newly developed drug (“D”) versus treatment as usual (“TAU”) on blood pressure control for people with high blood pressure (“hypertensives”). You obtain data from hypertensives who had high blood pressure at baseline (“high BP group”) and relatively lower levels of blood pressure at baseline (“low BP group”) and obtained the following data (refer to the table below):
“`
Levels of blood pressure control in a study on the effectiveness of drug D versus TAU

| Condition | TAU group (N = 200) | D group (N = 200) |
|-----------|---------------------|-------------------|
| Low BP    | 81/87 (93%)        | 234/270 (87%)      |
| High BP   | 192/263 (73%)        | 55/80 (69%)      |
| Combined  | 273/350 (78%)        | 289/350 (83%)    |
```

Based on the data presented above, which of the following statements is CORRECT?

Q21. In your community, the prevalence of cigarette smoking among adults is 20%. You know the relative risk of cigarette smoking for lung cancer is about 20.0 (i.e., RR = 20.0). Assuming cigarette smoking is the ONLY cause of lung cancer, if you were to achieve 100% smoking cessation in your community, by how much would the incidence of lung cancer reduce? (Calculate the population attributable fraction of smoking cessation for lung cancer). Select the CORRECT value from the following figures

Q22. In your community, 10% of the population are exposed to Radon gas, 10% exposed to asbestos, and 20% people smoke. Exposure to all three (Radon, asbestos, and smoking) are high risks of lung cancer, with RRs between 10-20. You found that when you add up the population attributable fractions, they amount to 174% of the burden of lung disease. Which of the following statements is a CORRECT explanation of why the three exposures add up to174% of the burden of lung cancer?

Q23. You have conducted a meta-analysis of randomised controlled trials to study whether aerobic exercise can prevent heart disease among people over 50 years of age, and found that regular aerobic exercise can prevent heart disease (pooled Odds Ratio = 6.3, 95%CI: 5.2-8.5). Considering you used only meta-analysis of RCTs with high effect size, which of the following is the CORRECT listing to support causality?

Q24. Which of the following can be used as an argument against “Temporality” criterion of Hill’s criteria?

Q25. Sherlock Holmes advised Dr Watson in “Sign of Four”, “… when you have eliminated the impossible, whatever remains, however improbable, must be the truth”. Which ONE of the Hill’s criteria fits best with this statement?

Q26. You want to investigate whether cigarette smoking causes lung cancer. You know that people above 50 years of age, and men are more likely to both smoke and have lung cancer. You also know that smoking causes changes in lung tissue you can measure that in turn lead to lung cancer. Which of the following will be a confounding variable in your study between lung cancer and smoking?

Q27. Observational studies have suggested that menopausal hormone therapy (HRT) are associated with lower the risk of heart attack and stroke for women with heart disease. But RCTs now shows that women with heart disease should not take it. Which of the following statements is CORRECT about explaining the differences?

Q28. You conducted a case-control study on the association between coffee consumption and pancreatic cancer with adequate sample size; pancreatic cancer cases were selected from the cancer ward of the hospital and healthy controls were general members of the public. You took history of their coffee consumption by asking them about their coffee consumption patterns. Which of the following is a threat to internal validity?

Q29. You conduct a survey of students at the University of Canterbury to find out the prevalence of low back pain among students using clinical examination. Which of the following statements is correct?

Q30. Which of the following statement is CORRECT about controlling for confounding variables in a study:

Q31. Which of the following statements is correct about Randomised controlled trials

Q32. You are appraising a case-control study on the association between smoking and myocardial infarction (heart attack) and found Odds Ratios for ex-smokers as 2.4 (95% Confidence interval: 1.3 - 3.2), and for current smokers 4.7 (95% Confidence Interval: 3.4-6.8); your reference category was “never smokers” (hence OR 1.00). You adjusted for age, education, cholesterol, high blood pressure, and BMI. Which of the following statements is CORRECT about the study findings:

Q33. Which of the following sequences correctly orders the hierarchy of evidence in terms of highest to lowest in the order of evidence (best to the least)?

Q34. Franz Messerli (2012) published a study in the New England Journal of Medicine and reported a significant linear correlation (r=0.791, P<0.0001) between per-capita chocolate consumption and the number of Nobel laureates per 10 million persons in a total of 23 countries. When Sweden was excluded, the correlation coefficient increased to 0.862. They stated, “The slope of the regression line allows us to estimate that it would take about 0.4 kg of chocolate per capita per year to increase the number of Nobel laureates in a given country by 1”. Based on this, which of the following statements is correct?

Q35. Which of the following is true about biases in randomised controlled trials:

 
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