07-04-2007, 11:04 AM
The following vignette applies to the next 2 items.
A 58-year-old white man comes to the emergency department because of chest heaviness for the past 45 minutes associated with shortness of breath and a sense of doom. He has not seen a physician since he was 18 years old. He smokes approximately two packs of cigarettes per day. He takes no prescription medications. He has had increasing heartburn recently and he has been taking eight to twelve antacid tablets daily during the past 3 weeks. He is mildly nauseated and diaphoretic. Vital signs are: temperature 37.2°C (99.0°F), pulse 98/min, respirations 20/min and blood pressure 160/96 mm Hg. Electrocardiogram shows that ST-T segment changes are indeterminate. You are aware of a new blood test, CQ, that can diagnose an acute myocardial infarction (MI) more quickly than the creatine kinase isoenzymes. The receiver operating characteristic (ROC) curve for CQ is shown in the exhibit for four cut-off points. You believe the likelihood of an acute MI is high in this patient and you want to minimize the chance of a false negative.
Item 1 of 2
7. Which of the following is the most appropriate cut-off point on the ROC curve?
A
) A
B
) B
C
) C
D
) D
E
) It cannot be determined with the data provided
Item 2 of 2
8.
The cut-off point at which the test performance for CQ is most accurate in the detection of an acute MI is which of the following?
A
) A
B
) B
C
) C
D
) D
E
) It cannot be determined from an ROC curve
End of Set
i don't have the graph.?
My doubt is----in the second q of the set wht do they mean by--most accurate in the detection of an acute MI -----are they asking abt most point of highest sensitivity or specificity or PPV ??
Note: There is a small paragraph in last clinical epidemiology lesson of washington manual----i have been searching for this ROC concept since long---i saw that just now.
hope it helps.
A 58-year-old white man comes to the emergency department because of chest heaviness for the past 45 minutes associated with shortness of breath and a sense of doom. He has not seen a physician since he was 18 years old. He smokes approximately two packs of cigarettes per day. He takes no prescription medications. He has had increasing heartburn recently and he has been taking eight to twelve antacid tablets daily during the past 3 weeks. He is mildly nauseated and diaphoretic. Vital signs are: temperature 37.2°C (99.0°F), pulse 98/min, respirations 20/min and blood pressure 160/96 mm Hg. Electrocardiogram shows that ST-T segment changes are indeterminate. You are aware of a new blood test, CQ, that can diagnose an acute myocardial infarction (MI) more quickly than the creatine kinase isoenzymes. The receiver operating characteristic (ROC) curve for CQ is shown in the exhibit for four cut-off points. You believe the likelihood of an acute MI is high in this patient and you want to minimize the chance of a false negative.
Item 1 of 2
7. Which of the following is the most appropriate cut-off point on the ROC curve?
A
) A
B
) B
C
) C
D
) D
E
) It cannot be determined with the data provided
Item 2 of 2
8.
The cut-off point at which the test performance for CQ is most accurate in the detection of an acute MI is which of the following?
A
) A
B
) B
C
) C
D
) D
E
) It cannot be determined from an ROC curve
End of Set
i don't have the graph.?
My doubt is----in the second q of the set wht do they mean by--most accurate in the detection of an acute MI -----are they asking abt most point of highest sensitivity or specificity or PPV ??
Note: There is a small paragraph in last clinical epidemiology lesson of washington manual----i have been searching for this ROC concept since long---i saw that just now.
hope it helps.