Introduction to Clinical Epidemiology (401173)ASSIGNMENT

QUESTION

 Introduction to Clinical Epidemiology (401173) FINAL ASSIGNMENT Autumn, 2019 Due date: 11.59pm , May 29 2019 This assignment is based on the learning objectives and concepts as  described in the Unit Learning Guide. There are 9 questions worth a  total of 64 marks and this assignment will contribute 64% towards the  total assessment for this subject. Your assignment should be typed, with adequate space left between  questions. Assignments should be submitted via vUWS. Be as concise as  possible in your answers, and use the number of marks allocated to each  question as a guide for how much to write. Please note this is an individual exercise. Late assignments will not be accepted without prior approval. You are required to answer ALL questions (1-9) Page 1 of 7 

Answer questions 1-2 based on the following scenarios: Q1: Fred, a 65-year-old obese man with a history of type 2 diabetes  mellitus and hypertension presents to the GP practice for a follow-up  appointment. During the consultation, he asks whether there is a better  medication to glicazide and metformin, his oral hypoglycemic  medications, which he has been taking to control his blood sugar. His  friend has recently been put on a newer oral hypoglycemic medication  (Liraglutide, a glucagon-like peptide-1 analogue), which has been shown  to help with weight management in patients with diabetes and obesity.  Fred has been finding it very difficult to lose weight for a few years  now as he has tried various lifestyle modifications. He asks whether the  new oral hypoglycemic medications could be an option for him in weight  reduction. 

Task [2 marks] a. Write a focused research question for this particular problem that  will help you organise a search of the literature for an answer (use the  PICO elements as appropriate). b. Identify the PICO elements in your research question Q2: In the past 2 years, as an Infectious Disease Specialist in one of  the tertiary hospitals in Australia, you have attended to 23 migrant  patients who were referred by their General Practitioners with symptoms  not typical of pulmonary tuberculosis. After taking a detailed history  and performing appropriate physical examinations, as well as reviewing a  range of relevant investigations, you clinically diagnosed and  microbiologically confirmed that those patients have multi-drug  resistance pulmonary tuberculosis (MDR-TB). The Public Health Department  was notified of disease and the patients were managed accordingly. Now,  you and some colleagues from Western Sydney University want to  investigate the risk factors for MDR-TB. 

Task [2 marks] a. Write a focused research question for this particular problem that  will help you organise a search of the literature for an answer (use the  PICO elements as appropriate). b. Identify the PICO elements in your research question 

Q3: Please select the single best answer for each of questions 3.I – VII I. Randomised controlled trials provide strong evidence that an observed  effect is due to the intervention. One main reason is because [1 mark]: a) When the study participants are randomised, many characteristics and  potential confounders are likely to be evenly distributed in the groups b) It is easier to measure the outcome variable with great precision in  randomised controlled trials compared to other study designs. c) The exposure level and the outcome are measured at the same time d) The study participants are volunteers and therefore motivated to take part in the study e) None of the above II.Blinding is an important feature of a randomised controlled trials because [1 marks]: a) It helps prevent measurement bias – the biased assessment of outcomes b) It helps reduce contamination and compliance problems c) It helps reduce confounding and selection bias d) It is required to do an intention-to-treat analysis e) It helps improve chance event and reduce misclassification III. Which of the following is true [1 mark]? a) Loss to follow-up can lead to selection bias in cohort studies. b) Selection bias can arise from conditioning on the common effect of  the exposure and an uncontrolled independent risk factor for the  outcome. c) Case-control studies are no more prone to selection bias than are cohort studies. d) Loss to follow-up is not a major source of bias in cohort studies. e) None of the above. IV. When epidemiologists judge the evidence to establish a possible cause of a health outcome, they 

consider [1 mark]: a) The strength of the association between an exposure and the outcome b) Evidence that the exposure of interest has appeared before the outcome. c) Evidence showing that reductions in the exposure level will reverse the risk of the outcome. d) A, B and C e) A and B only V. A double-blind study was designed to test the efficacy of a drug. One  group of the patients consisting of 1227 participants were given a  placebo and the other group of patients consisting of 1220 were given  the active drug. Both groups were to be followed up for one year. After  6-months of the trial, 35% of participants in the placebo groups dropped  out of the study and 4% of the participants taking the active drug  dropped out of the study. What is the SINGLE BEST explanation for this  occurrence [1 mark]? a) Failure of the active drug b) Insufficient information to interpret data c) Systematic error d) Chance event e) Breakdown of the double-blind study VI. The highest level of evidence provided for cancer treatment usually comes from: [1 mark] a) Randomised control trials b) Phase II clinical trials c) Phase III clinical trials d) Systematic reviews of observational studies e) Meta-analyses of intervention studies Page 3 of 7 

VII. A recent study examined the association between tea consumption and  ovarian cancer. The study included 414 women with primary epithelial  ovarian, fallopian, or peritoneal cancer and 868 age-and region-matched  women with non-neoplastic conditions. The adjusted odds ratio was 0.39  for those drinking tea daily and 0.23 for those drinking tea for 30  years, compared with non-tea drinkers. The study concluded that  increasing frequency and duration of tea drinking, especially green tea,  can reduce the risk of ovarian cancer. What type of study was conducted? [1 mark] a) Cross-sectional study b) Prospective cohort study c) Randomised controlled trial d) Retrospective cohort study e) Case control study Q4: Now select ONLY ONE research question from either Question 1 or 2  above that will help you organize a search of the clinical literature  for an answer. If you were to search Medline/PubMed/Web of science for  original research on this question: a. Describe what your search strategy would be, including keywords, MeSH  terms, inclusion and exclusion criteria, as well as evidence of the  Boolean operators used [4 marks]. b. What type of study design would best be able to address your selected research question? State why [1 mark]. c. Cite the best article from among those you find, using any referencing style of your choice [1 mark]. 

Q5: Answer questions 5a-b based on the following information: A total of 1800 patients have a screening test to identify a protein  called “FEN-59’ to determine patients at risk of lung carcinoma,  followed by a standardized lung biopsy procedure. Of the 1800 children,  1533 have a negative FEN-59 and 267 have a positive FEN-59. In addition,  a lung biopsy (gold standard) was done on all patients. Of those  patients with a negative FEN-59, 1491 have a negative lung biopsy. In  the group with a positive FEN-59, 259 have a positive lung biopsy. Construct a 2×2 table using the information provided above, and answer the following questions (a and b): a) Calculate the sensitivity of the FEN-59 [2 marks] b) Calculate the positive predictive value of the FEN-59 [2 marks] c) The negative predictive value is dependent on all of the following:  prevalence, incidence, sensitivity and specificity [True/False] [1 mark] Please select the SINGLE BEST answer in questions 5e to f d) Using the image below, which value in the test result units is the point of maximum specificity? [1 mark] a) 30 b) 15 c) 5 d) 20 e) 25 e) A study was conducted in which 10,000 women participated. All women  underwent a cervical smear. 1,000 of 10,000 women had a positive smear.  Of these, 100 developed cervical cancer. 10 women who had negative smear  developed cancer. What is the SINGLE most likely terminology to  describe the 10 women with negative results who developed cervical  cancer? [1 mark] a. True negative b. False negative c. True positive d. False positive e. Chance event 

Q6: Answer questions 6a-d based on the following information: You have brought to the attention of the hospital medical services that a  published trial reported reduced body weight in patients with morbid  obesity who were treated with liraglutide, a glucagon-like peptide-1  equivalent. You mentioned this published paper to your Director, and  given the evidence reported, he asked you to give a presentation about  the study findings during the weekly seminar series. In your  presentation, she has asked you to address the following questions  (6a-d) based on the results of the published paper (Edited abstract is  shown below): A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight  Management (Xavier Pi-Sunyer, M.D., Arne Astrup, M.D., D.M.Sc., Ken  Fujioka et al. N Engl J Med 2015;373:11-22. 

DOI: 10.1056/NEJMoa1411892) Background: Obesity is a chronic disease with serious health  consequences, but weight loss is difficult to maintain through lifestyle  intervention alone. Liraglutide, a glucagonlike peptide-1 analogue, has  been shown to have potential benefit for weight management at a  once-daily dose of 3.0 mg, injected subcutaneously. Methods: We conducted a 56-week, double-blind trial involving 3731  patients who did not have type 2 diabetes and who had a body-mass index  of at least 30 or a BMI of at least 27 if they had treated or untreated  dyslipidemia or hypertension. We randomly assigned patients in a 2:1  ratio to receive once-daily subcutaneous injections of liraglutide at a  dose of 3.0 mg (2487 patients) or placebo (1244 patients); both groups  received counselling on lifestyle modification. Results: At week 56, patients in the liraglutide group had lost a mean  of 8.4±7.3 kg of body weight, and those in the placebo group had lost a  mean of 2.8±6.5 kg (a difference of -5.6 kg; 95% confidence interval,  -6.0 to -5.1; P 0.001). A total of 63.0% of the patients in the  liraglutide group as compared with 37.0% in the placebo group lost at  least 5% of their body weight (P 0.001). Conclusion: In this study, 3.0 mg of liraglutide, as an adjunct to diet  and exercise, was associated with reduced body weight and improved  metabolic control. Q6a. Construct a 2×2 table using relevant figures shown in the abstract, and answer the following questions: [4 marks] (i) What is the risk of losing at least 5% of body weight in all patients included in the study? (ii) What is the risk of losing at least 5% of body weight in patients who were treated with liraglutide? (iii) What is the risk of losing at least 5% of body weight in patients who were treated with placebo? (iv) What is the relative risk of treatment with liraglutide verus  placebo with regard to weight management? How would you interpret this  relative risk estimate? Q6b. If equal numbers of patients in the population were treated with  liraglutide vs placebo treatment, what would be the expected population  relative risk reduction (RRR) for liraglutide treatment? How would you  interpret this measure? [4 marks] Q6c. How many patients need to be treated with liraglutide for one more  patient to benefit compared with the placebo? What is this measure  called? How would you interpret this measure [4 marks]? Q6d. How does the measure in question 5b differ from question 5c? [4 marks] 

Read the attached original research article (Khorana et al., 2019), available in vUWS), and now answer Questions 7 to 9: Q7. What characteristics of the study would you consider in order to  determine if its findings are valid? Include wider considerations of  study quality/validity and give examples. (Q8 will address relevance,  and the next question will ask how to determine the importance of the  findings…for this question, focus on the internal validity of the study)  [8 marks] Q8. What characteristics of the findings would you consider, in order,  to determine if they are clinically meaningful and statistically  significant? Include examples. (You’ve already addressed validity…for  this question, focus on how to determine the clinical significance and  statistical significance of an effect reported in the study) [8 marks] Q9. What characteristics of the study would you consider, in order, to  determine if it is generalizable to your context? Explain your answers  and provide examples. (Questions 6 and 7 have asked how to determine if  the study is valid, and how important the findings are….for this  question, focus on how to determine if it is really relevant or  generalizable to your practice.) [8 marks] Note: 0 Please do not list the characteristics in questions 8–10, but explain your answers succinctly. 0 You can also download the article from the University Library using your student login details. 


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