Please Help Urgently,
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12 points possible (graded)
This week, we discussed a 2000 study in the New England Journal of Medicine (NEJM) that compared patients with rheumatoid arthritis who were randomly assigned to take either Vioxx or a conventional pain reliever, naproxen. In 2005, it came to the attention of the editors of the NEJM that three heart attacks from the Vioxx group were deliberately omitted from the data published in the paper (the authors truncated the study early to avoid inclusion of these three late events). The corrected data are shown below:
The revised numbers including the three additional heart attacks.
Number per group Person-years of exposure* Number of heart attacks
Vioxx group 4047 2698 20
Naproxen group 4029 2699 4
Reference: Curfman GD, Morrissey S, Drazen JM. Expression of concern: Bombardier et a., "Comparison of upper gastronintestinal toxicity of rofecoxib and naproxen in patients with reeumatoid arthritis," N Engle J Med 2000;343:1520-8. N Engl J Med 2005; 353:2813-4.
Question 1.
What is the absolute difference in the incidence rates of heart attacks for Vioxx versus Naproxen? Please calculate as events per 1000 person-years and round to the nearest tenth (e.g., x.x); do not write the units when entering your answer.
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Question 2.
What is the absolute difference in the risk of heart attacks for Vioxx versus Naproxen? Please report as a percentage, rounded to the nearest hundredth (e.g., .xx). Do not include the % sign.
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Question 3.
What is the rate ratio comparing Vioxx with Naproxen? Please round to the nearest tenth (e.g., x.x).
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Question 4.
What is the number needed to harm? Round to the nearest whole number.
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Question 5.
The following figure comes from a retrospective cohort study in which researchers compared HIV patients on three different anti-retroviral treatment regiments—one pill per day, two pills per day, and three or more pills per day—in terms of adherence to treatment and hospitalization.
Bar chart showing percentage adjusted risk of hospitalization for single pill per day, two pills per day, and three pills per day regimens. Single pill per day regimen= 7.7%, two pills per day regimen= 9.9%, three pills per day regimen= 9.9%
What percent of single-pill users were hospitalized during follow-up? (do not include the % sign)
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Question 6.
What percent of three-or-more-pill users were hospitalized during follow-up? (eg. x.x, do not include the % sign)
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Question 7.
Calculate the risk ratio comparing the risk of hospitalization in single-pill users versus three-or-more-pill users. Round to the nearest hundredth (e.g., .xx).
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Question 8.
Calculate the odds ratio comparing the odds of hospitalization in single-pill users versus three-or-more-pill users. Round to the nearest hundredth (e.g., .xx).
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The following table displays the results of a double-blind randomized weight-loss trial that compared three doses of the drug tesofensine (0.25 mg, 0.5mg, and 1.0mg) with a placebo pill. The authors reported the percentage of patients in each group that achieved a weight loss of 5kg or more and the percentage who achieved a weight loss of 10kg or more.
Placebo Tesofensine Odds ratio (95% Cl)
0.25mg 0.5mg 1.0mg 0.25mg tesofensine 0.5mg tesofensine 1.0mg tesofensine
Weight reduction of 5kg or more
<5kg 32 (71%) 20 (41%) 6 (13%) 4 (9%) 4.0 (1.6-9.9; p=0.0023) 20.9 (6.8-64.3; p<0.0001) 31.5 (9.0-111.0; p<0.0001)
≥5kg 13 (29%) 29 (59%) 41 (87%) 42 (91%)
Weight reduction of 10kg or more
<10kg 42 (93%) 32 (65%) 22 (47%) 12 (26%) 9.5 (2.4-37.4; p=0.0013) 23.0 (5.8-42.0; p<0.0001) 57.7 (13.7-242.0; p<0.0001)
≥10kg 3 (7%) 17 (35%) 25 (53%) 34 (74%)
Question 9.
What is the likely reason that the authors have reported odds ratios rather than risk ratios or rate ratios for these data?
The data come from a case-control study.
They analyzed the data with logistic regression.
They cannot calculate rates or risks from their data.
Odds ratios are the preferred measure of relative risk.
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Question 10.
The adjusted odds ratio comparing the1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 5kg or more was 31.5. Calculate the unadjusted risk ratio for this comparison (using the percentages given in the table). Round to the nearest tenth (e.g., x.x).
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Question 11.
The adjusted odds ratio comparing the1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 5kg or more was 31.5. Calculate the adjusted risk ratio for this comparison using the conversion formula below. Round to the nearest tenth (e.g., x.x).
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Question 12.
Which of the following is the best way for the authors to interpret the odds ratio of 57.7 (comparing the1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 10kg or more) for their readers?
The drug increases a persons’ chance of losing at least 10kg by 57.7-fold.
The drug increases a person’s odds of losing at least 10kg by 57.7-fold.
The odds ratio here is highly misleading; thus, the authors should only report the odds ratio if they additionally give the readers the unadjusted or adjusted risk ratio.
Okay, just help in this one only. So that i can understand:
Placebo Tesofensine Odds ratio (95% Cl)
0.25mg 0.5mg 1.0mg 0.25mg tesofensine 0.5mg tesofensine 1.0mg tesofensine
Weight reduction of 5kg or more
<5kg 32 (71%) 20 (41%) 6 (13%) 4 (9%) 4.0 (1.6-9.9; p=0.0023) 20.9 (6.8-64.3; p<0.0001) 31.5 (9.0-111.0; p<0.0001)
≥5kg 13 (29%) 29 (59%) 41 (87%) 42 (91%)
Weight reduction of 10kg or more
<10kg 42 (93%) 32 (65%) 22 (47%) 12 (26%) 9.5 (2.4-37.4; p=0.0013) 23.0 (5.8-42.0; p<0.0001) 57.7 (13.7-242.0; p<0.0001)
≥10kg 3 (7%) 17 (35%) 25 (53%) 34 (74%)
Question 10.
The adjusted odds ratio comparing the1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 5kg or more was 31.5. Calculate the unadjusted risk ratio for this comparison (using the percentages given in the table). Round to the nearest tenth (e.g., x.x).
unanswered
Question 11.
The adjusted odds ratio comparing the1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 5kg or more was 31.5. Calculate the adjusted risk ratio for this comparison using the conversion formula below. Round to the nearest tenth (e.g., x.x).
The adjusted odds ratio comparing the1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 5kg or more was 31.5. Calculate the adjusted risk ratio for this comparison using the conversion formula below. Round to the nearest tenth (e.g., x.x).
To answer these questions, we need to perform calculations based on the provided data. Let's go through each question and explain how to get the answers.
Question 1: What is the absolute difference in the incidence rates of heart attacks for Vioxx versus Naproxen? Please calculate as events per 1000 person-years and round to the nearest tenth (e.g., x.x).
To calculate the incidence rate, divide the number of events (heart attacks) by the person-years of exposure and multiply by 1000. For Vioxx: 20 heart attacks / 2698 person-years * 1000 = Answer 1
Question 2: What is the absolute difference in the risk of heart attacks for Vioxx versus Naproxen? Please report as a percentage, rounded to the nearest hundredth (e.g., .xx). Do not include the % sign.
To calculate the risk difference, subtract the risk in the reference group (Naproxen) from the risk in the Vioxx group. For Vioxx: 20 heart attacks / 2698 person-years = risk_Vioxx, For Naproxen: 4 heart attacks / 2699 person-years = risk_Naproxen. Risk difference = risk_Vioxx - risk_Naproxen * 100 = Answer 2
Question 3: What is the rate ratio comparing Vioxx with Naproxen? Please round to the nearest tenth (e.g., x.x).
To calculate the rate ratio, divide the incidence rate in the Vioxx group by the incidence rate in the Naproxen group. Rate ratio = incidence rate_Vioxx / incidence rate_Naproxen = Answer 3
Question 4: What is the number needed to harm? Round to the nearest whole number.
The number needed to harm represents the number of individuals who would need to be exposed to the treatment (Vioxx) for one additional person to experience harm compared to the control group (Naproxen). It can be calculated as the reciprocal of the risk difference: Number needed to harm = 1 / (risk_Vioxx - risk_Naproxen) = Answer 4
Question 5: What percent of single-pill users were hospitalized during follow-up? (do not include the % sign)
The percentage can be calculated by multiplying the proportion of single-pill users hospitalized by 100. Answer 5 = Single-pill users hospitalized / Total number of single-pill users * 100
Question 6: What percent of three-or-more-pill users were hospitalized during follow-up? (eg. x.x, do not include the % sign)
Similar to question 5, Answer 6 can be calculated by multiplying the proportion of three-or-more-pill users hospitalized by 100.
Question 7: Calculate the risk ratio comparing the risk of hospitalization in single-pill users versus three-or-more-pill users. Round to the nearest hundredth (e.g., .xx).
The risk ratio can be calculated as the risk of hospitalization in single-pill users divided by the risk of hospitalization in three-or-more-pill users. Risk ratio = Risk_single-pill / Risk_three-or-more-pill = Answer 7
Question 8: Calculate the odds ratio comparing the odds of hospitalization in single-pill users versus three-or-more-pill users. Round to the nearest hundredth (e.g., .xx).
The odds ratio can be calculated using the provided odds ratio (95% Cl) values. Answer 8 = Odds ratio_single-pill / Odds ratio_three-or-more-pill
Question 9: What is the likely reason that the authors have reported odds ratios rather than risk ratios or rate ratios for these data?
The correct answer can be found in the given options. Read the provided options and select the one that best explains the authors' choice.
Question 10: The adjusted odds ratio comparing the 1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 5kg or more was 31.5. Calculate the unadjusted risk ratio for this comparison (using the percentages given in the table). Round to the nearest tenth (e.g., x.x).
The unadjusted risk ratio can be calculated by dividing the proportion of patients achieving the outcome in the tesofensine group by the proportion in the placebo group. Answer 10 = Proportion_1.0mg tesofensine / Proportion_placebo
Question 11: The adjusted odds ratio comparing the 1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 5kg or more was 31.5. Calculate the adjusted risk ratio for this comparison using the conversion formula below. Round to the nearest tenth (e.g., x.x).
The adjusted risk ratio can be calculated by converting the given adjusted odds ratio using the provided conversion formula. Answer 11 = exp(ln(Adjusted odds ratio)) = exp(ln(31.5))
Question 12: Which of the following is the best way for the authors to interpret the odds ratio of 57.7 (comparing the1.0 mg tesofensine group with the placebo group for the outcome of a weight loss of 10kg or more) for their readers?
Read the provided options and select the one that best represents an accurate interpretation of the odds ratio.
I hope this explanation helps you solve the questions. If you have any further questions, feel free to ask!