Literature Eval Midterm Practice

1. Studies with larger sample populations are more likely to have good external validity or generalizability.

True

False

(Course Assessment #1) Larger studies are more generalizable than smaller studies.

Explanation

(Course Assessment #1) Larger studies are more generalizable than smaller studies.

2. What does the study NOT tell us? Select all the apply:

The optimum dose of a drug (studies usually evaluate just one or two different doses)

The optimum duration of therapy (usually just one duration is measured)

Whether another drug might have been more effective in the particular population

Whether certain combination therapies might be more effective

(Putting it all together softchalk)

Explanation

(Putting it all together softchalk)

Submit

3. Practice guidelines in the United States use the same evidence-grading system, so an evidence rating of 2C can be universally applied across all guidelines.

True

False

(course assessment #2) Practice guidelines use a wide variety of evidence-grading systems to grade their recommendations. A rating of 2C in one guideline may be based on different criteria than a 2C rating in another guideline.

Explanation

(course assessment #2) Practice guidelines use a wide variety of evidence-grading systems to grade their recommendations. A rating of 2C in one guideline may be based on different criteria than a 2C rating in another guideline.

4. When deciding how to use the findings of a clinical trial, which of the following should be considered?

Validity of the evidence

Clinical significance of the findings

Risk versus benefit

All the above

(course assessment #2) All of these factors should be considered in making a determination about whether a study's findings should change our practice.

Explanation

(course assessment #2) All of these factors should be considered in making a determination about whether a study's findings should change our practice.

5. In a randomized, controlled trial, Phil's Heart Supplement was compared to placebo for reducing the risk of myocardial infarction in patients with existing cardiovascular disease. One hundred (100) patients received Phil's Heart Supplements and 100 patients received placebo. After 2 years of treatment, 25 patients receiving Phil's Heart Supplement experienced a myocardial infarction. In the placebo group, 35 patients experienced a myocardial infarction. The difference was statistically significant (P < 0.05).Calculate the the relative risk of myocardial infarction and select the correct answer below.

0.71

1.4

0.69

0.61

(assessing results softchalk) Relative risk is probability in the treatment group divided by probability in the control group. In this question, RR = 25/35 = 0.71

Explanation

(assessing results softchalk) Relative risk is probability in the treatment group divided by probability in the control group. In this question, RR = 25/35 = 0.71

6. In the 4S study 4444 patients with high cholesterol and CHD were given either simvastatin or placebo. After treatment for 5.4 years the following results were found: Simvastatin group: 182 (8%) died Placebo group: 256 (12%) died RR = 8% / 12% or 0.08 / 0.12 = 0.66From this we can conclude what about simvastatin and the risk of the chance of death:

Since the result is < 1, then we can determine that simvastatin reduced the risk or the chance of death.

Sine the result is < 1, then we can determine that simvastatin increased the risk or the chance of death.

There is no significant difference between groups.

We do not have enough information to answer.

(assessing results softchalk) Note: RR is always expressed as a decimal, not as a percentage. When we are interpreting a RR, we look to see if that decimal is above or below 1. Then we can assess HOW MUCH it is above or below 1 by calculating the RR increase or RR decrease.

Explanation

(assessing results softchalk) Note: RR is always expressed as a decimal, not as a percentage. When we are interpreting a RR, we look to see if that decimal is above or below 1. Then we can assess HOW MUCH it is above or below 1 by calculating the RR increase or RR decrease.

7. A study provides results for the relative risk of myocardial infarction in patients receiving drug X: 95% CI = 0.75 (0.6-0.93)Drug X appears to reduce the risk of myocardial infarction somewhere in the range of: _-_%

(Assessing results softchalk) in this example risk REDUCTION is calculated as follows:

1-0.6 = 0.4 = 40%

1-0.93 = 0.07 = 7%

Explanation

(Assessing results softchalk) in this example risk REDUCTION is calculated as follows:

1-0.6 = 0.4 = 40%

1-0.93 = 0.07 = 7%

Submit

8. A study provides results for the relative risk of myocardial infarction in patients receiving drug X: 95% CI = 0.75 (0.6-0.93)What is the relative risk for myocardial infarction?

(Assessing results softchalk)

Explanation

(Assessing results softchalk)

Submit

9. Setting filters on a search increases the number of results retrieved.

True

False

(Course Assessment #1) Adding filters to a search decreases the number of results retrieved. This allows the searcher to zero in on the most relevant information to answer the question.

Explanation

(Course Assessment #1) Adding filters to a search decreases the number of results retrieved. This allows the searcher to zero in on the most relevant information to answer the question.

10. For most clinical questions regarding drug therapies, the most relevant research design is usually a:

Randomized controlled trial

Population Study

Cohort study

Case study

(Course Assessment #1) Randomized controlled trials are typically preferred for evaluating therapies because they are capable of showing cause-and-effect. Other study designs are not capable of showing cause-and-effect.

Explanation

(Course Assessment #1) Randomized controlled trials are typically preferred for evaluating therapies because they are capable of showing cause-and-effect. Other study designs are not capable of showing cause-and-effect.

11. What are the ultimate goals of medicine?

Improve health

Improve quality of life

Reduce cholesterol

Improve quantity of life

Save health care dollars

Ultimately, the purpose of medicine comes down to two goals - improving quality and quantity of life. (Intro to EBP softchalk)

Explanation

Ultimately, the purpose of medicine comes down to two goals - improving quality and quantity of life. (Intro to EBP softchalk)

Submit

12. You are writing a review article on HMG-CoA reductase inhibitors (statins) and need to gather clinical trials evaluating their efficacy. You are particularly interested in determining which, if any, of the statins have a mortality benefit in secondary prevention. After conducting your search and setting your filters you read through the article abstracts and choose only those studies which assessed patient mortality as an outcome. Thus, studies looking at mortality would meet your ___________ criteria.

Inclusion

Exclusion

Evidence

Cherry-picking

(Course Assessment #1) In order to further narrow a search after defining search terms and setting filters it is important to select appropriate inclusion and exclusion criteria. In this case, you are "including" articles that met a specific "criteria" (in this case mortality as a study outcome), hence the term "inclusion criteria".

Explanation

(Course Assessment #1) In order to further narrow a search after defining search terms and setting filters it is important to select appropriate inclusion and exclusion criteria. In this case, you are "including" articles that met a specific "criteria" (in this case mortality as a study outcome), hence the term "inclusion criteria".

13. Which of the following is not a low level question?

Is lithium available as an oral solution?

What are the storage requirements for dabigatran?

Does the evidence support the use of montelukast for migraine prevention?

What are the FDA-approved indications for gabapentin?

(Course Assessment #1) This is a high level question related to the therapeutic efficacy of montelukast. The other options are low level questions related to drug product availability, storage, and indications.

Explanation

(Course Assessment #1) This is a high level question related to the therapeutic efficacy of montelukast. The other options are low level questions related to drug product availability, storage, and indications.

14. Evidence-based practice gives us the tools we need to know if the diagnostic tests and treatments we give actually contribute to achieving our ultimate goals.

True

False

(Intro to EBP softchalk)

Explanation

(Intro to EBP softchalk)

15. Confidence intervals can tell us if results are statistically significant just like a P value. They can also give us a much more descriptive picture of the true treatment effects.

True

False

(Assessing results softchalk)

Explanation

(Assessing results softchalk)

16. Read the abstract below. Which of the following is true about the finding related to the primary outcome? Coenzyme Q10 (CoQ10) deficiency has been proposed to be causal in 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor (statin)-induced myopathies. However, the clinical benefit of supplementation is unproved. The purpose of the present study was to assess the effect of CoQ10 supplementation on myalgias presumed to be caused by statins. Patients currently receiving a statin who developed new-onset myalgias in ≥ 2 extremities within 60 days of initiation or a dosage increase were eligible. Patients continued statin therapy and were randomized using a matched design to either CoQ10 60 mg twice daily or matching placebo. Double-blind treatment continued for 3 months, and patients completed a 10-cm visual analog scale (VAS) and the Short-Form McGill Pain Questionnaire at baseline and at each monthly visit. The primary end point was the comparison of the VAS score at 1 month. A total of 76 patients were enrolled (40 in the CoQ10 arm and 36 in the placebo arm). The mean VAS score was 6 cm at baseline in both groups. At 1 month, no difference was seen in the mean VAS score between the 2 groups (3.9 cm in the CoQ10 group and 4 cm in the placebo group; p = 0.97). However, 5 patients in the CoQ10 group and 3 in the placebo group discontinued therapy during the first month because of myalgias. The baseline median score on the Sensory Pain Rating Index subscale was 10 in the CoQ10 group and 11.5 in the placebo group. At 1 month, these scores had decreased to 6.5 and 7.5, respectively, with no statistically significant difference (p = 0.34). In conclusion, CoQ10 did not produce a greater response than placebo in the treatment of presumed statin-induced myalgias.

The difference is not statistically significant.

There is a statistically significant difference.

The difference is statistically significant, but not clinically significant.

The difference is clinically significant, but not statistically significant.

(assessing results softchalk) The P value is 0.97 for the primary outcome of VAS. This is a p value > 0.05 which means that it is not statistically significant.

Explanation

(assessing results softchalk) The P value is 0.97 for the primary outcome of VAS. This is a p value > 0.05 which means that it is not statistically significant.

17. P value tells us the direction of the difference (better or worse, higher or lower, etc) and it tells us the strength or magnitude of the treatment effect.

True

False

(assessing results softchalk) P vale does not tell us either of these things.

Explanation

(assessing results softchalk) P vale does not tell us either of these things.

18. In a randomized, controlled trial, Phil's Heart Supplement was compared to placebo for reducing the risk of myocardial infarction in patients with existing cardiovascular disease. One hundred (100) patients received Phil's Heart Supplements and 100 patients received placebo. After 2 years of treatment, 25 patients receiving Phil's Heart Supplement experienced a myocardial infarction. In the placebo group, 35 patients experienced a myocardial infarction. The difference was statistically significant (P < 0.05). Calculate the the relative risk reduction or increase for myocardial infarction and select the correct answer below.

29% reduction

39% increase

71% reduction

39% reduction

(assessing results softchalk) RRR or RRI is calculation by determining how far above or below 1 the RR is. In this example, we are calculating a RRR because the RR is below one. RRR = 1-0.71 = 29%

Explanation

(assessing results softchalk) RRR or RRI is calculation by determining how far above or below 1 the RR is. In this example, we are calculating a RRR because the RR is below one. RRR = 1-0.71 = 29%

19. In a randomized, controlled trial, Phil's Heart Supplement was compared to placebo for reducing the risk of myocardial infarction in patients with existing cardiovascular disease. One hundred (100) patients received Phil's Heart Supplements and 100 patients received placebo. After 2 years of treatment, 25 patients receiving Phil's Heart Supplement experienced a myocardial infarction. In the placebo group, 35 patients experienced a myocardial infarction. The difference was statistically significant (P < 0.05).What is the probability for the treatment group and the control group?

Treatment = 25% Control = 35%

Treatment = 75%Treatment = 75% Control = 65%

Treatment = 35% Control = 25%

Treatment = 71% Control = 40%

(assessing results softchalk) To calculate probability take the number of events in a group and divide by the total number in that group. So for the treatment group, probability = 25/100 = 25%. For placebo, 35/100 = 35%

Explanation

(assessing results softchalk) To calculate probability take the number of events in a group and divide by the total number in that group. So for the treatment group, probability = 25/100 = 25%. For placebo, 35/100 = 35%

20. In a randomized, controlled trial, Phil's Heart Supplement was compared to placebo for reducing the risk of myocardial infarction in patients with existing cardiovascular disease. One hundred (100) patients received Phil's Heart Supplements and 100 patients received placebo. After 2 years of treatment, 25 patients receiving Phil's Heart Supplement experienced a myocardial infarction. In the placebo group, 35 patients experienced a myocardial infarction. The difference was statistically significant (P < 0.05). Calculate the the absolute difference for myocardial infarction and select the correct answer below.

10%

4%

0.71

29%

(assessing results softchalk) Absolute difference is probability in one group minus probability in the other. In this case, AD = 35% - 25% = 10%. Remember AD has no + or - associated with it.

Explanation

(assessing results softchalk) Absolute difference is probability in one group minus probability in the other. In this case, AD = 35% - 25% = 10%. Remember AD has no + or - associated with it.

21. Which of the following is included in "the big three" validity assessments?

Was patient allocation adequately concealed?

Were groups similar at baseline?

Was a per-protocol or intention to treat analysis used?

Were patients in each group treated similarly?

Allocation concealment is one of the big three validity measures, in addition to randomization and blinding.

Explanation

Allocation concealment is one of the big three validity measures, in addition to randomization and blinding.

22. If the NNH is lower than the NNT then more people will experience harm than will experience benefit.

True

False

(assessing results softchalk) Also, if the NNT is lower than the NNH, then more people will experience benefit than will experience harm.

Explanation

(assessing results softchalk) Also, if the NNT is lower than the NNH, then more people will experience benefit than will experience harm.

23. In a randomized, controlled trial, Phil's Heart Supplement was compared to placebo for reducing the risk of myocardial infarction in patients with existing cardiovascular disease. One hundred (100) patients received Phil's Heart Supplements and 100 patients received placebo. After 2 years of treatment, 25 patients receiving Phil's Heart Supplement experienced a myocardial infarction. In the placebo group, 35 patients experienced a myocardial infarction. The difference was statistically significant (P < 0.05). Calculate the the number needed to treat for myocardial infarction and select the correct answer below.

10

3

4

5

(assessing results softchalk) NNT = 100/AD (%). In this case 100/10 = 10.

Explanation

(assessing results softchalk) NNT = 100/AD (%). In this case 100/10 = 10.

24. A P value of 0.05 means that there is a 5% probability that an observed difference is actually due to chance. Similarly, there is a 95% probability that the observed difference represents a true difference that is not due to chance.

True

False

(Assessing Results softchalk) As the P value gets smaller, the smaller probability there is that an observed difference is solely due to chance.

Explanation

(Assessing Results softchalk) As the P value gets smaller, the smaller probability there is that an observed difference is solely due to chance.

25. When there is a 1 to 1 ratio or a relative risk of "1" then there is a statistical difference

True

False

(assessing results softchalk) Most treatment studies assess relative risk or odds ratios. This data is expressed as percentage or ratio. For these studies, confidence intervals that cross or contain 1 are not statistically significant. This is because "1" is within the range of possibilities. When there is a 1 to 1 ratio or a relative risk of "1" then there is no difference

Explanation

(assessing results softchalk) Most treatment studies assess relative risk or odds ratios. This data is expressed as percentage or ratio. For these studies, confidence intervals that cross or contain 1 are not statistically significant. This is because "1" is within the range of possibilities. When there is a 1 to 1 ratio or a relative risk of "1" then there is no difference

26. Which of the following is an appropriate method for random allocation?

Flipping a coin

Drawing straws

Assignment based on eye color

Drawing numbers from a hat

(Course Assessment #1) Any random process such as flipping a coin is appropriate for randomization. The other methods listed cannot ensure a random result.

Explanation

(Course Assessment #1) Any random process such as flipping a coin is appropriate for randomization. The other methods listed cannot ensure a random result.

27. A physician asks you about the interaction between proton pump inhibitors and clopidogrel. After researching the question, you make a recommendation to the physician to use rabeprazole 20mg daily in his patient. You base your recommendation on a handful of conflicting studies that use patient-oriented evidence. Most trials agree that rabeprazole is a safe and effective option, but they don't all agree. Based on the kind of evidence used, what SORT rating would you give this recommendation?

B

A

C

(Course assessment #2) A SORT rating of B is given when the evidence supporting the recommendation is inconsistent or limited quality patient oriented evidence.

Explanation

(Course assessment #2) A SORT rating of B is given when the evidence supporting the recommendation is inconsistent or limited quality patient oriented evidence.

28. From top to bottom, which of the following is in the correct order with regard to the hierarchy of evidence?

Systematic Reviews, Randomized Controlled Trials, Cohort Studies, Expert Opinion

Cohort Studies, Systematic Reviews, Expert Opinion, Randomized Controlled Trials

Randomized Controlled Trials, Cohort Studies, Systematic Reviews, Expert Opinion

Expert Opinion, Randomized Controlled Trials, Systematic Reviews, Cohort Studies

(course assessment #2) Evidence at the top of the hierarchy is generally of higher quality and has more authority than evidence at the bottom. The hierarchy of evidence from top to bottom follows: systematic reviews and meta-analyses, randomized controlled trials, cohort studies, case-control studies, cross-sectional studies, case series, case reports, editorials, and expert opinion.

Explanation

(course assessment #2) Evidence at the top of the hierarchy is generally of higher quality and has more authority than evidence at the bottom. The hierarchy of evidence from top to bottom follows: systematic reviews and meta-analyses, randomized controlled trials, cohort studies, case-control studies, cross-sectional studies, case series, case reports, editorials, and expert opinion.

29. When a clinical trial provides a hazard ratio for the primary outcome, it is appropriate to also calculate the relative risk.

True

False

(Course assessment #2) It doesn't make sense to calculate a Relative Risk when a Hazard Ratio is provided because the Hazard Ratio is more informative than a simple Relative Risk.

Explanation

(Course assessment #2) It doesn't make sense to calculate a Relative Risk when a Hazard Ratio is provided because the Hazard Ratio is more informative than a simple Relative Risk.

30. A patient comes to your pharmacy and asks if the supplement SAM-e will help with her fibromyalgia symptoms. You do some research and find that a few limited quality trials with patient oriented evidence found SAM-e to be beneficial for reducing fibromyalgia symptoms. You recommend that the patient give SAM-e a try. True or False: You should tell the patient that your recommendation has an evidence rating of B.

True

False

(course assessment #2) Grading evidence is done to better communicate the confidence of specific recommendations to healthcare professionals. Including an evidence rating when discussing therapy with a patient would likely lead to confusion.

Explanation

(course assessment #2) Grading evidence is done to better communicate the confidence of specific recommendations to healthcare professionals. Including an evidence rating when discussing therapy with a patient would likely lead to confusion.

31. Evidence-based practice is defined by three components. Select the three components of evidence-based practice.

Systematic searching

Clinical experience

The best available evidence

The most current evidence

Randomized controlled trials

(Course Assessment #1) The three components of evidence-based practice are using the best available evidence identified through systematic searching and using that evidence in combination with clinical experience.

Explanation

(Course Assessment #1) The three components of evidence-based practice are using the best available evidence identified through systematic searching and using that evidence in combination with clinical experience.

Submit

32. Which of the following are components of a well-built clinical question? Choose all that apply.

Patient or Problem

Patient Prognosis

Intervention or treatment

Outcomes

Comparison

(Course Assessment #1) PICO is an acronym we can use to help us define a well-built question. P=Patient or problem I = Intervention or treatment C = Comparison O = Outcomes

Explanation

(Course Assessment #1) PICO is an acronym we can use to help us define a well-built question. P=Patient or problem I = Intervention or treatment C = Comparison O = Outcomes

Submit

33. Systematic searching is important because it... (choose all that apply):

Ensures that we look for the right kind of information to answer the question.

Allows us to cherry pick evidence.

Helps us know when to stop searching.

Improves our efficiency in identifying evidence.

(Course Assessment #1) Systematic searching is important because it ensures that we look for the right kind of information to answer the question, helps us know when to stop searching, improves our efficiency in identifying evidence, and prevents us from cherry-picking evidence.

Explanation

(Course Assessment #1) Systematic searching is important because it ensures that we look for the right kind of information to answer the question, helps us know when to stop searching, improves our efficiency in identifying evidence, and prevents us from cherry-picking evidence.

Submit

34. Which of the following outcomes would be considered patient-oriented evidence?

HbA1c

Kidney failure

Hamilton D Rating Scale

LDL levels

Stroke

(Course Assessment #1) Patient oriented outcomes are those that patients notice and care about. Kidney failure and stroke are serious conditions that significantly impact a patients quality of life. Similarly, the Hamilton-D rating scale measures symptoms of depression - another measure of how a patient feels.

Explanation

(Course Assessment #1) Patient oriented outcomes are those that patients notice and care about. Kidney failure and stroke are serious conditions that significantly impact a patients quality of life. Similarly, the Hamilton-D rating scale measures symptoms of depression - another measure of how a patient feels.

Submit

35. Review the following abstract and select the primary outcome below: Coenzyme Q10 (CoQ10) deficiency has been proposed to be causal in 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor (statin)-induced myopathies. However, the clinical benefit of supplementation is unproved. The purpose of the present study was to assess the effect of CoQ10 supplementation on myalgias presumed to be caused by statins. Patients currently receiving a statin who developed new-onset myalgias in ≥ 2 extremities within 60 days of initiation or a dosage increase were eligible. Patients continued statin therapy and were randomized using a matched design to either CoQ10 60 mg twice daily or matching placebo. Double-blind treatment continued for 3 months, and patients completed a 10-cm visual analog scale (VAS) and the Short-Form McGill Pain Questionnaire at baseline and at each monthly visit. The primary end point was the comparison of the VAS score at 1 month. A total of 76 patients were enrolled (40 in the CoQ10 arm and 36 in the placebo arm). The mean VAS score was 6 cm at baseline in both groups. At 1 month, no difference was seen in the mean VAS score between the 2 groups (3.9 cm in the CoQ10 group and 4 cm in the placebo group; p = 0.97). However, 5 patients in the CoQ10 group and 3 in the placebo group discontinued therapy during the first month because of myalgias. The baseline median score on the Sensory Pain Rating Index subscale was 10 in the CoQ10 group and 11.5 in the placebo group. At 1 month, these scores had decreased to 6.5 and 7.5, respectively, with no statistically significant difference (p = 0.34). In conclusion, CoQ10 did not produce a greater response than placebo in the treatment of presumed statin-induced myalgias.What was the primary outcome?

VAS Score at 1 month

McGill Pain Questionaire

Sensory Pain Rating Index at baseline

Statin-induced myalgia

(Assessing Results softchalk) The VAS is a commonly used way to measure pain. It is quick and simple. The abstract specifically states that this was the primary endpoint.

Explanation

(Assessing Results softchalk) The VAS is a commonly used way to measure pain. It is quick and simple. The abstract specifically states that this was the primary endpoint.

36. In a study, 100 people were treated with vitamin D and 100 people received placebo control during the flu season. The researchers wanted to determine if vitamin D treated was associated with the risk of developing the flu. In the vitamin D group 22 patients developed the flu. In the placebo group, 29 patients developed the flu. The finding was statistically significant with a p < 0.05. Calculate the number needed to treat.

14

7%

4

Cannot be calculated with the values given.

(Course assessment #2) NNT = 100/AD. In this case the absolute difference is 7%. 100/7 = 14.

Explanation

(Course assessment #2) NNT = 100/AD. In this case the absolute difference is 7%. 100/7 = 14.

37. You are conducting a systematic search in PubMed to identify guidelines for the treatment of prostate cancer. Which of the following filters would NOT be appropriate.

Article type: Randomized Controlled Trial

Language: English

Species: Human

Article Type: Practice Guideline

(Course Assessment #1) Filtering this search to randomized controlled trials would not allow you to efficiently and effectively identify guidelines for treating prostate cancer. Adding filters for English language, human subjects, and practice guidelines would be appropriate in this case.

Explanation

(Course Assessment #1) Filtering this search to randomized controlled trials would not allow you to efficiently and effectively identify guidelines for treating prostate cancer. Adding filters for English language, human subjects, and practice guidelines would be appropriate in this case.

38. Which of the following are steps in the evidence-based approach to answering questions? Choose all that apply.

Applying evidence to the patient case.

Defining the question

Critically appraising the evidence

Searching PubMed

Assessing study size and power

(Course Assessment #1) The evidence-based approach to answering questions includes 4 steps: 1.) define the question, 2.) Systematically search the literature, 3.) Critically appraise the evidence, and 4.) Apply the evidence to the patient or case.

Explanation

(Course Assessment #1) The evidence-based approach to answering questions includes 4 steps: 1.) define the question, 2.) Systematically search the literature, 3.) Critically appraise the evidence, and 4.) Apply the evidence to the patient or case.

Submit

39. In a randomized, double-blind clinical trial, researchers were evaluating patients to determine the effect of Zombrex on mortality compared to placebo. At baseline, 45% of the patients in the treatment group were considered obese. In the placebo group, 25% were considered to be obese. Based on this information, this study is at risk for which threat to validity?

Confounding

Measurement bias

Expectation bias

Analysis bias

(Course Assessment #1) Confounding is a concern because obesity is linked to mortality outcomes and it is occurring at a higher rate in one group than in another.

Explanation

(Course Assessment #1) Confounding is a concern because obesity is linked to mortality outcomes and it is occurring at a higher rate in one group than in another.

40. Which of the following is a threat to validity? Choose all that apply.

Selection bias

Crossover study design

Financial conflict of interest

Confounding

Chance

(Course Assessment #1) Each of these factors (chance, confounding, and selection bias), can potentially invalidate study findings. Financial conflict of interest may prompt you to examine the study more closely, but is not evidence of bias in the study's design or conduct. Crossover study design does not inherently impact the validity of a trial.

Explanation

(Course Assessment #1) Each of these factors (chance, confounding, and selection bias), can potentially invalidate study findings. Financial conflict of interest may prompt you to examine the study more closely, but is not evidence of bias in the study's design or conduct. Crossover study design does not inherently impact the validity of a trial.

Submit

41. Which of the following is an adequate method for concealing allocation?

Third party random sequence assignment

Random allocation

Using a matching placebo treatment

Flipping a coin

(Course Assessment #1) Using a third party, which separates the process of enrollment and randomization, is appropriate for allocation concealment.

Explanation

(Course Assessment #1) Using a third party, which separates the process of enrollment and randomization, is appropriate for allocation concealment.

42. Most published studies don't actually have an impact on practice or don't necessitate a change in practice.

True

False

(Putting it all together softchalk) This is because they often evaluate disease-oriented outcomes (e.g., blood pressure). Typically, practice changes are made when more than one study shows that a particular therapy offers an advantage over other approaches in terms of patient-oriented outcomes.

Explanation

(Putting it all together softchalk) This is because they often evaluate disease-oriented outcomes (e.g., blood pressure). Typically, practice changes are made when more than one study shows that a particular therapy offers an advantage over other approaches in terms of patient-oriented outcomes.

43. Review the following study abstract. Note that the primary outcome is knee pain severity as measured by the WOMAC scale. Which of the answers below correctly identifies the type of data for this outcome? OBJECTIVE: To determine whether vitamin D supplementation reduces symptom and structural progression of knee OA. DESIGN, SETTING, AND PATIENTS: A 2-year randomized, placebo-controlled, double-blind, clinical trial involving 146 participants with symptomatic knee OA (mean age, 62.4 years [SD, 8.5]; 57 women [61%], 115 white race [79%]). Patients were enrolled at Tufts Medical Center in Boston between March 2006 and June 2009. INTERVENTION: Participants were randomized to receive either placebo or oral cholecalciferol, 2000 IU/d, with dose escalation to elevate serum levels to more than 36 ng/mL. MAIN OUTCOME MEASURES: Primary outcomes were knee pain severity (Western Ontario and McMaster Universities [WOMAC] pain scale, 0-20: 0, no pain; 20, extreme pain), and cartilage volume loss measured by magnetic resonance imaging. Secondary end points included physical function, knee function (WOMAC function scale, 0-68: 0, no difficulty; 68, extreme difficulty), cartilage thickness, bone marrow lesions, and radiographic joint space width. RESULTS: Eighty-five percent of the participants completed the study. Serum 25-hydroxyvitamin D levels increased by a mean 16.1 ng/mL (95% CI, 13.7 to 18.6) in the treatment group and by a mean 2.1 mg/mL (95% CI, 0.5 to 3.7) (P < .001) in the placebo group. Baseline knee pain was slightly worse in the treatment group (mean, 6.9; 95% CI, 6.0 to 7.7) than in the placebo group (mean, 5.8; 95% CI, 5.0 to 6.6) (P = .08). Baseline knee function was significantly worse in the treatment group (mean, 22.7; 95% CI, 19.8 to 25.6) than in the placebo group (mean, 18.5; 95% CI, 15.8 to 21.2) (P = .04). Knee pain decreased in both groups by a mean -2.31 (95% CI, -3.24 to -1.38) in the treatment group and -1.46 (95% CI, -2.33 to -0.60) in the placebo group, with no significant differences at any time. The percentage of cartilage volume decreased by the same extent in both groups (mean, -4.30; 95% CI, -5.48 to -3.12 vs mean, -4.25; 95% CI, -6.12 to -2.39) (P = .96). There were no differences in any of the secondary clinical end points. CONCLUSION AND RELEVANCE: Vitamin D supplementation for 2 years at a dose sufficient to elevate 25-hydroxyvitamin D plasma levels to higher than 36 ng/mL, when compared with placebo, did not reduce knee pain or cartilage volume loss in patients with symptomatic knee OA.

Continuous

Nominal

Ordinal

Categorical

(assessing results softchalk) As described in the abstract, the WOMAC scale measures pain on a scale of 0-20. This data is sequenced and has a set value distance or value between each. Another clue is that in the results section, the authors provide a mean value for the data. Mean values or averages can be calculated for continuous data. They cannot be calculated for other data types.

Explanation

(assessing results softchalk) As described in the abstract, the WOMAC scale measures pain on a scale of 0-20. This data is sequenced and has a set value distance or value between each. Another clue is that in the results section, the authors provide a mean value for the data. Mean values or averages can be calculated for continuous data. They cannot be calculated for other data types.

44. Which of the following is NOT an experimental study design?

Crossover Study

Cohort Study

Randomized Controlled Trial

(Course Assessment #1) Cohort studies is an example of a population or observational study. The others are experimental designs.

Explanation

(Course Assessment #1) Cohort studies is an example of a population or observational study. The others are experimental designs.

45. Most of us feel more comfortable interpreting relative risk than odds ratio; however, in some study designs, a relative risk cannot be used. Which study design cannot use a relative risk calculation to estimate risk?

Case control study

Cohort study

RTC

Cross sectional study

(course assessment #2) Relative risk cannot be used with case-control studies because participants are selected based on an outcome rather than an exposure.

Explanation

(course assessment #2) Relative risk cannot be used with case-control studies because participants are selected based on an outcome rather than an exposure.

46. In a study using a time-to-event analysis and measuring healing rates, the hazard ratio gives the odds that a patient receiving treatment will heal faster than a patient receiving placebo. What additional information does the median ratio give?

How much faster healing occurred with treatment compared to placebo

The relative risk of healing faster

The probability of healing faster with treatment compared to placebo

The median ratio cannot be used with time-to-event analyses

(Course assessment #2) The median ratio gives information on how much faster healing might occur.

Explanation

(Course assessment #2) The median ratio gives information on how much faster healing might occur.