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Question 1

Equation for sensitivity

Answer 1

Sensitivity= #True positives/ (#True positives + #False negatives)

Sensitivity = 1 - false negative rate

“Positive In Disease” PID

Question 2

Equation for specificity

Answer 2

Specificity = #True negatives/ (#True negatives + # False positives)

Specificity = 1 - false positive rate

“Negative In Health” NIH

Question 3

Equation for positive predictive value

Answer 3

PPV = # True positives / (#True + False positives)

Question 4

Equation for negative predictive value

Answer 4

NPV = # True negatives / (# True + False negatives)

Question 5

How do PPV and NPV change with prevalence?

Answer 5

HIGHER prevalence will INCREASE PPV
HIGHER prevalence will DECREASE NPV

LOWER prevalence will DECREASE PPV
LOWER prevalence will INCREASE NPV

Question 6

What quality is desired for a screening test?

Answer 6

HIGH SENSITIVITY– we want to make sure we get ALL of the true positives, even if there are false negatives

Question 7

What quality is desired for a diagnostic test?

Answer 7

HIGH SPECIFICITY– we want to make sure we ACCURATELY diagnose people!!

Question 8

An infant presents to the ER with vomiting. What features would lead you to suspect congenital pyloric stenosis?

Answer 8

• 2-6 weeks old
• First born males»> (generally m»>f)
• non bilious, projectile vomiting, dehydration, metabolic alkalosis with hypokalemia and ^Cl-

Question 9

What is the Plummer Vinson Triad?

Answer 9

• esophageal webbing
• glossitis
• Fe+ deficiency anemia

Question 10

What is Dressler syndrome?

Answer 10

Autoimmune attack of myocardium 2-4 weeks after MI

Presents with chest pain, fever and high sed rate