• Shuffle
Toggle On
Toggle Off
• Alphabetize
Toggle On
Toggle Off
• Front First
Toggle On
Toggle Off
• Both Sides
Toggle On
Toggle Off
Toggle On
Toggle Off
Front

### How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

Play button

Play button

Progress

1/24

Click to flip

### 24 Cards in this Set

• Front
• Back
 What is Sensitivity? = proportion of patients who have disease who test positive = true positives / (true positives + false negatives) What is Specificity? = proportion of patients who do not have the disease who test negative = true negatives / (true negatives + false positives) Sensitive tests... Rule Out (snOUT) Specific tests... Rule In (spIN) Receiver Operating Curce (ROC) High Cutoff = Medium Cutoff = Low Cutoff = High = Specific, nonSensitive Medium = between Low = non-specific, Sensitive Positive Predictive Value = post test probability Probability of Having the Disease Given a Positive Result = TP / (FP + TP) Negative Predictive Value = post test probability TN / (FN + TN) How does the fact that a disease is rare (low pretest probability) affect the interpretation of a positive test? A positive test may actually be more likely to come from a healthy person FP > TP !!! Anxiety What is the Treatment Threshold? When the post-test probability is high enough, Treat. What is the Test Threshold? When the post-test probability is low enough, Stop Testing. What is likelihood ratio? probability of result in those who have the disease / probability of result in those who do have the disease What is likelihood ratio if test is positive? Sensitivity / (1 - Specificity) What is likelihood ratio if test is negative? (1 - sensitivity) / specificity The Nomogram: why do you use it? Draw a line from the pre-test probability through the likelihood ratio to get to the post test probability What magnitudes of LRs are useful? > 5-10 for rule in < 0.1 - 0.2 for rule out What is Efficacy? = usefulness in ideal circumstances What is Effectiveness? = usefulness in usual circumstances What is a surrogate outcome? An outcome that stands in for desired clinical outcome, e.g. increased CD4 count in ARVs or decreased cholesterol in preventing MIs Is fever a good surrogate outcome for predicting death from sepsis? No. Can give acetominaphen to reduce fever but death will happen regardless. What is a Type I error? Probability of finding difference in populations despite absence of difference What is a Type II error? Probability of finding no difference when difference exists = beta. Power = 1 - beta. What is NNT? Number needed to treat. NNT = 1 / ARR What are good cutoffs for NNT? Treatment? Prophylaxis? Tx = 2 - 5 Prophylaxis = 10 - 100 What is NNH? NNH = 1 / ARI