Quiz 1

Question 1 A clinical trial is done to determine whether a new drug would increase the 5year survival of patients with breast cancer. The final analysis shows that the relative risk of death for those taking the drug is 0.8 (95% CI = 0.6-0.9). Which one best describes the result? This new drug increases the risk of death by 80% The risk of death after taking the new drug is now 80% The risk of death after taking the new drug is reduced by 80% This new drug increases the risk of death by 20%

Question 2 A clinical trial is done to determine whether a drug would improve the overall 5-year survival of patients with colon cancer. After a mean followup of 5.4 years, the final analysis shows that of the 325 subjects randomized to take the drug, 25 died. Of the 326 subjects who took placebo, 34 died during the follow-up period. The relative risk of death for taking the drug is: 0.36 0.74 9.0 1.36 Question 3 The best study design that can answer a question regarding the benefit of a therapeutic intervention is: Cross sectional survey Cohort study Randomized controlled trial Case-control study Question 4 In literature search of articles about treatment and/or prevention, the best methodological filter is; randomized, controlled trial (RCT) Bolerian theorem Thesaurus literary prescription

Question 5 A RCT of a new drug seeking to reduce infection rates following gastrointestinal surgery reveals a relative risk of 1.25 (95% CI 1.03-1.65). This result is best interpreted as: The new drug is not better than the control drug. The new drug is worse than the control drug.

The new drug is possibly better but needs further studies. The new drug confers the same benefit compared with the control drug. Question 6 A clinical trial is done to determine whether a drug would increase the 5year survival of patients with breast cancer. The final analysis shows that the relative risk of death for those taking the drug is 0.8 (95% CI = 0.41.3). Which one of the following p values is consistent with the result? A p value of less than 0.05 A p value of less than 0.01 A p value of 0.05 A p value of greater than 0.05 Question 7 The efficacy of a new treatment for a particular disease should be compared to; placebo prevailing standard treatment any other drug different doses of the same drug Question 8 A RCT of a new antidepressant drug reports that there is no difference in outcome between the drug and placebo (p greater than 0.05) in reducing episodes of depression. However, an additional previously unplanned analysis of the data was able to demonstrate a better response rate for the new drug versus placebo in the women in the trial (p=0.04). Which one of the following is the most valid conclusion from this trial? The trial should have listed 2 primary outcomes The new drug works in women but not in men The response rate reported for the entire group should be analyzed as a secondary outcome A prospective trial designed to test the drug in men compared to women should be considered Question 9 A clinical trial is done to determine whether a new chemotherapeutic intervention would increase the survival of patients with breast cancer. The result shows that the relative risk of death for the experimental arm is 0.7 (95% CI = 0.5-0.8). Which one best describes the result? This new intervention increases the risk of death by 70% The risk of death following the intervention is now only 70%. The risk of death following the intervention is reduced by 70%

This new intervention increases the risk of death by 30%.

Question 10 To determine if you would believe the outcome of an RCT for therapy in spite of incomplete follow up, which process should be done: Intention to treat analysis Worse case scenario analysis Both Neither Question 11 A study involving 100 subjects post breast surgery comparing the efficacy of a drug in reducing postoperative infection gives the following result. Drug A (Control) = 12 cases of post op infection (0.12) and Drug B (Experimental) = 7 cases of post op infection (0.07). Considering that subjects were accounted for, what is the number needed to treat? 5 10 15 20

Question 12 Drug A is for prevention of stroke. Studies on Drug A report risk reduction of stroke, risk reduction of hypertension, control of high serum cholesterol and lipid levels and decrease appetite for fatty and oily food. Which is a surrogate outcome? Hypertension stroke appetite to fatty and oily food serum cholesterol and lipid levels uestion 13 A clinical trial is done to determine whether an oncologic drug would improve the survival of colon cancer patients. After a mean follow-up of 4.1 years, the final analysis shows that of the 365 subjects randomized to take the drug, 15 died while of the 366 subjects who took placebo, 34 died. To prevent one death, you have to treat: 9 19 36 72 Question 14

A study involving 100 subjects post breast surgery comparing the efficacy of a drug in reducing postoperative infection gives the following result. Drug A (Control) = 12 cases of post op infection (0.12) and Drug B (Experimental) = 7 cases of post op infection (0.07). Considering that subjects were accounted for what is the absolute risk reduction? 1.71 0.58 .05 .42 Question 15 The most important advantage of a randomized controlled clinical trial over other study designs in determining treatment benefit is: The subject population can be equally allocated to each of the groups Blinding of the subjects and researchers can be done Unknown variables that may influence outcome are equally distributed Data are collected prospectively Question 16 Which part of the article/manuscript should one look at to check whether the randomization was effective? Abstract Table 1 of Results Conclusion Statistical significance of results Question 17 Why is randomization important in a study comparing treatment? To eliminate/minimize bias To ensure that the groups would have equal chances of falling under the experimental or control arm To ensure that the result/outcome is due to the intervention being tested and not to any confounder All of the above are correct Question 18 A RCT is conducted to test the hypothesis that a new vasodilator improves congestive heart failure. Patients are randomized to either the new drug or to placebo while continuing their pre-trial drugs. At the end of the trial, intention-to-treat analysis shows no statistical difference in outcome. The authors then decide to perform an analysis based on actual therapies that patients received. Data from patients who did not finish at least 60% of their assigned drug would be included in the placebo group. This time the analysis shows that the new drug is better than placebo (p less than 0.05). Which of the following is the best course of action based on these results? Recommend the drug for all patients with congestive heart failure.

Recommend the new drug for patients who adhere to their current therapies. Only recommend the new drug for early stage congestive heart failure. Do not recommend the new drug and wait for further studies. Question 19 The best study design to determine the presence of any treatment advantage between an intervention and placebo is: Cross sectional survey Cohort study Randomized controlled trial Case-control study Question 20 In a randomized controlled trial involving two drugs to be tested for efficacy, a process that ensures that both investigators and subjects will not know the treatment arm that a certain group belongs to is to make similar preparations of the drug in terms of color, packaging etc. This process is called: Random allocation Secret allocation Double dummy Double blinding Question 21 After an adequate history taking and complete physical examination the clinician have an initial clinical impression, differential diagnoses and personal preferences whether to treat, not to treat or do diagnostic workups. This is reflected in the:

Spectrum of disease diagram Upper testing threshold Lower testing threshold Pre-test probability of disease Question 22 One hundred (100) females, 40-50 years old is admitted due to persistent right upper quadrant pain for the past 12 hours had an ultrasound of the abdomen. US findings were as follows (50 acute cholecystitis, 10 salphingitis, and 10 right ovarian cyst) while in 30 the readings were ‘normal’ or indeterminate or no abnormality noted. Surgery was done in 50 of the 70 with positive findings and the ultrasound readings were compared with the operative/histopathologic findings (45 acute cholecystitis, 2 ovarian cyst, and 3 pelvic inflammatory disease). The rest (50) who were not immediately operated were followed up until final resolution during the hospitalization (25 acute gastro-enteritis, 20 pelvic inflammatory disease, and 5 subsequently operated for

appendicitis). The verification bias was avoided by:

Doing the ultrasound and reference standard to all study subjects Just operating on those with positive findings Complete follow-up Complete follow-up Question 23 A 45 year-old female with right upper quadrant pain, nausea and vomiting presents in your clinic, she wants to know if she needs immediate surgery for Acute Cholecystitis. 10%

25%

80%

0 -------/--------/--------------------------------/-------------100% Lower TT Pre-test Prob.

Upper TT

What is the best methodologic filter for a question on diagnosis? Sensitivity Clinical trial patient Cohort studies Guidelines Question 24 A 45 year-old female with right upper quadrant pain, nausea and vomiting presents in your clinic, she wants to know if she needs immediate surgery for Acute Cholecystitis. 10%

25%

80%

0 -------/--------/--------------------------------/--------------100% Lower TT Pre-test Prob.

Upper TT

The most likely question in this scenario is: What is the best diagnostic test that will detect will detect acute cholecystitis among women with right upper quadrant pain? What is the diagnosis? When do you recommend surgery in right upper quadrant pain? What is the relevance of right upper quadrant pain among women?

Question 40 Sensitivity = 0.50, specificity = 0.50 of this particular test. Clinically the test is;

Useful when result is positive Useful when results are negative Relatively accurate Useless Question 39 "150 females, 11-20 years old admitted due to persistent abdominal pain for 6-12 hours had ultrasound of the lower abdomen. Of these, 70 had positive findings (50 acute appendicitis, 5 salphingitis, 5 right ovarian cyst, 10 fluid accumulation at the right gutter/pelvis) while in 80 the readings were 'normal' or indeterminate or no abnormality noted. Surgery was done in 65 of the 70 with positive findings and the ultrasound readings were compared with the operative/histopathologic findings (55 acute appendicitis, 5 ovarian cyst, 2 ruptured Graffian Follicle, 3 pelvic inflammatory disease). The rest (85) who were not immediately operated were followed up until final resolution during the hospitalization (65 acute gastro-enteritis, 8 cystitis, 7 pelvic inflammatory disease, 5 subsequently operated for appendicitis. The diagnostic test being evaluated is: Histopatholo gy Surgical findings Ultrasound Follow-up Question 38 The Magnetic Resonance Imaging (MRI) of the lungs was compared with CT guided aspiration biopsy findings in patients with solitary solid pulmonary nodule by chest X-Ray. Inclusion criteria for subject selection included what diagnostic test? Pulmonary MRI Pulmonary CT Chest Xray Solitary solid nodule Question 37 "150 females, 11-20 years old admitted due to persistent abdominal pain for 6-12 hours had ultrasound of the lower abdomen. Of these, 70 had positive findings (50 acute appendicitis, 5 salphingitis, 5 right ovarian cyst, 10 fluid accumulation at the right gutter/pelvis) while in 80 the readings were 'normal' or indeterminate or no abnormality noted. Surgery was done in 65 of the 70 with positive findings and the ultrasound readings were compared with the operative/histopathologic findings (55 acute appendicitis, 5 ovarian cyst, 2 ruptured Graffian Follicle, 3 pelvic inflammatory disease). The rest (85) who were not immediately operated were followed up until final resolution during the hospitalization (65 acute gastro-enteritis, 8 cystitis, 7 pelvic inflammatory disease, 5 subsequently operated for appendicitis. The pretest odds is: 0.4 0.1

0.8 0.7 5 Question 36 "150 females, 11-20 years old admitted due to persistent abdominal pain for 612 hours had ultrasound of the lower abdomen. Of these, 70 had positive findings (50 acute appendicitis, 5 salphingitis, 5 right ovarian cyst, 10 fluid accumulation at the right gutter/pelvis) while in 80 the readings were 'normal' or indeterminate or no abnormality noted. Surgery was done in 65 of the 70 with positive findings and the ultrasound readings were compared with the operative/histopathologic findings (55 acute appendicitis, 5 ovarian cyst, 2 ruptured Graffian Follicle, 3 pelvic inflammatory disease). The rest (85) who were not immediately operated were followed up until final resolution during the hospitalization (65 acute gastro-enteritis, 8 cystitis, 7 pelvic inflammatory disease, 5 subsequently operated for appendicitis. If the cells of the 2 X 2 table contain: a = 60; b = 5; c = 5; d = 80. The sensitivity is: 0.8 0.9 2 0.8 5 0.7 4 Question 35 The Magnetic Resonance Imaging (MRI) of the lungs was compared with CT guided aspiration biopsy findings in patients with solitary solid pulmonary nodule by chest X-Ray. In this study, the reference standard used is; Pulmonary MRI CT guided biopsy Solitary solid nodule Chest x-ray Question 34 "150 females, 11-20 years old admitted due to persistent abdominal pain for 6-12 hours had ultrasound of the lower abdomen. Of these, 70 had positive findings (50 acute appendicitis, 5 salphingitis, 5 right ovarian cyst, 10 fluid accumulation at the right gutter/pelvis) while in 80 the readings were 'normal' or indeterminate or no abnormality noted. Surgery was done in 65 of the 70 with positive findings and the ultrasound readings were compared with the operative/histopathologic findings (55 acute appendicitis, 5 ovarian cyst, 2 ruptured Graffian Follicle, 3 pelvic inflammatory disease). The rest (85) who were not immediately operated were followed up until final resolution during the hospitalization (65 acute gastro-enteritis, 8 cystitis, 7 pelvic inflammatory disease, 5 subsequently operated for appendicitis. If the cells of the 2 X 2 table contain: a = 60; b = 5; c = 5; d = 80. The clinical decision when the diagnostic test is positive: The patient should undergo surgery The patient need no surgery and medical treatment will do Repeat the diagnostic procedure or do another test

No clinical decision Question 33 After adequate history taking and complete physical examination the clinician has a primary initial clinical impression, some differential diagnoses and personal preferences whether to treat, not to treat or do diagnostic work-ups. This is reflected in the: Spectrum of disease diagram Upper testing threshold Lower testing threshold Pre-test probability of disease Question 32 "150 females, 11-20 years old admitted due to persistent abdominal pain for 6-12 hours had ultrasound of the lower abdomen. Of these, 70 had positive findings (50 acute appendicitis, 5 salphingitis, 5 right ovarian cyst, 10 fluid accumulation at the right gutter/pelvis) while in 80 the readings were 'normal' or indeterminate or no abnormality noted. Surgery was done in 65 of the 70 with positive findings and the ultrasound readings were compared with the operative/histopathologic findings (55 acute appendicitis, 5 ovarian cyst, 2 ruptured Graffian Follicle, 3 pelvic inflammatory disease). The rest (85) who were not immediately operated were followed up until final resolution during the hospitalization (65 acute gastro-enteritis, 8 cystitis, 7 pelvic inflammatory disease, 5 subsequently operated for appendicitis. If the cells of the 2 X 2 table contain: a = 60; b = 5; c = 5; d = 80. The clinical decision when the diagnostic test is negative/indeterminate/normal/no abnormality is: The patient should undergo surgery The patient need no surgery and medical treatment will do Repeat the diagnostic procedure or do another test No clinical decision Question 31 "150 females, 11-20 years old admitted due to persistent abdominal pain for 6-12 hours had ultrasound of the lower abdomen. Of these, 70 had positive findings (50 acute appendicitis, 5 salphingitis, 5 right ovarian cyst, 10 fluid accumulation at the right gutter/pelvis) while in 80 the readings were 'normal' or indeterminate or no abnormality noted. Surgery was done in 65 of the 70 with positive findings and the ultrasound readings were compared with the operative/histopathologic findings (55 acute appendicitis, 5 ovarian cyst, 2 ruptured Graffian Follicle, 3 pelvic inflammatory disease). The rest (85) who were not immediately operated were followed up until final resolution during the hospitalization (65 acute gastro-enteritis, 8 cystitis, 7 pelvic inflammatory disease, 5 subsequently operated for appendicitis. If the cells of the 2 X 2 table contain: a = 60; b = 5; c = 5; d = 80. The likelihood ratio of a test positive is: 15 10 5 0.8 5

Question 30

A population-based study was conducted of annual screening for breast cancer with sonomammography. The subjects underwent baseline evaluation in 1995, with repeat annual examinations the next 2 years. Confirmation of a breast cancer diagnosis was based on cellular pathology. Cancer + Sonomammogra + 56 532 phy - 4 13194 What is the likelihood ratio for a negative test result? 0.07 0.09 5 44 23.9 Question 29

A 25 year-old female with epigastric pain, anorexia, nausea and vomiting (2X) since 6 a.m. tod for appendicitis was performed which shows the following;

Histopath (appendicitis) Present Absent Ultrasoun Test d positive Test negative TOTAL

TOTAL

50

a

7

b

57 a+b

8

c

35

d

43 c+d 100 a+b+c+d

58 a+c

42 b+d

The pre-test odds is: 1.3 8 0.4 0.1 0.6 7 Question 28 A 45 year-old female with right upper quadrant pain, nausea and vomiting presents in your clinic, she wants to know if she needs immediate surgery for Acute Cholecystitis. 10%

25%

80%

0 -------/--------/--------------------------------/--------------100% Lower TT Pre-test Prob.

Upper TT

Your clinical action is:

Request for a diagnostic test Perform surgery now Treat patient as a case of peptic ulcer disease Re-evaluate patient for missing data in history and PE Quest ion 27 A 45 year-old female with right upper quadrant pain, nausea and vomiting presents in your clinic, she wants to know if she needs immediate surgery for Acute Cholecystitis. 10%

25%

80%

0 -------/--------/--------------------------------/--------------100% Lower TT Pre-test Prob.

Upper TT

The article most relevant to the case scenario is: The Accuracy of Ultrasound in the Diagnosis of Acute Cholecystitis Among Females with Significant Abdominal Pain Increased White Blood Cell count Influence Diagnosis in Abdominal Pain

Sensitivity and Specificity of Double Contrast Barium Enema in Detecting Ileo-cecal Problems of Elders with Right Iliac Pain Alvarado’s Criteria in the Diagnosis of Acute Appendicitis Among Males, 10-19 years old Quest ion 26 A 45 year-old female with right upper quadrant pain, nausea and vomiting presents in your clinic, she wants to know if she needs immediate surgery for Acute Cholecystitis. 10%

25%

80%

0 -------/--------/--------------------------------/--------------100% Lower TT Pre-test Prob.

Upper TT

The study population in this scenario is: Women with right upper quadrant pain Patients with acute cholecystitis Women presenting at the clinic

Women 45 years old Quest ion 25

Replication and standardization of a diagnostic test improve: Reliability Accuracy Validity Sensitivity