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Review / Wrong Answers > 6/3 UWorld > Flashcards

6/3 UWorld Flashcards

1
Q

Mutation and presentation of Williams syndrome

A

Microdeletion of long arm of chromosome 7 (deletion includes elastin gene)

“Elfin” facies, intellectual disability, hypercalcemia, well-developed verbal skills, extreme friendliess with strangers

THINK: Will Ferrel in the movie elf

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2
Q

Presentation of Gardner syndrome

A
  • Familial adenomatous polyposis + tumors outside the colon
  • Osteomas / soft tissue tumors
  • Supernumerary teeth
    • THINK: Gardener from the Kaposi sketchy
      • Digging through haustra-shaped planters à FAP
      • Digs up a bone à osteoma
      • Old lady smiles with extra teeth à supernumerary teeth
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3
Q

Mutation and presentation of Tuberous sclerosis

A
  • Due to mutated hamartin (or tuberin) gene
    • TSC1/TSC2 mutation on chromosome 16
  • Triad:
    • Angiofibromas, mental retardation, seizures
  • Other symptoms: Ash-leaf spots, hamartomas of CNS and skin, angiomyolipoma
  • Incomplete penetrance and variable presentation
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4
Q

Presentation of VHL disease

A

Presentation = HARP

  • Hemangioblastoma (retina, brainstem, cerebellum)
  • Angiomatosis
  • bilateral Renal cell carcinoma
  • Pheochromocytoma
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5
Q

Compare pathogenesis in albinism vs. vitiligo

A

Albinism = normal melanocyte number with decreased melanin production (due to decreased tyrosinase activity)

Vitiligo = autoimmune destruction of melanocytes

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6
Q

What are the branches of the common hepatic artery

A
  • Common hepatic artery
    • Gastroduodenal artery
      • R gastroepiploic = greater curvature of stomach (anastomoses with L gastroepiploic)
      • Anterior superior pancreaticoduodenal à head of pancreas, proximal duodenum
    • Right gastric artery = lesser curvature of stomach (anastomoses with L gastric a.)
    • Proper hepatic artery
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7
Q

Differentiate between case-control study and cohort study

A

Case control = compare a group with disease to group without disease and look for prior exposures/risk factors (is retrospective)

Cohort study = compare a group with risk factor to a group without risk factor and look for likelihood of disease (can be prosepective or retrospective)

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8
Q

Differentiate between incidence and prevalence

A
  • Prevalence = existing cases at a point in time
  • Incidence = number of new cases during a specific time period
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9
Q

Using this table, what are the formulas for sensitivity, specificity, PPV, and NPV

A
  • Sensitivity = true positive rate
    • Proportion of people with the disease who get a positive test result
    • TP / (TP + FN)
  • Specificity = true negative rate
    • Proportion of people without the disease who get a negative test result
    • TN / (TN + FP)
  • Positive predictive value
    • Proportion of positive test results that actually have the disease
    • TP / (TP + FP)
  • Negative predictive value
    • Proportion of negative test results that don’t actually have the disease
    • TN / (TN + FN)
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10
Q

Which values (sensitivity, specificity, PPV, NPV), change with disease prevalence

A

PPV and NPV

  • Positive predictive value
    • TP / (TP + FP)
    • Increases with increased disease prevalence
      • Total # with disease increases, so TP and FN increase
      • Increased TP = increased PPV
  • Negative predictive value
    • TN / (TN + FN)
    • Decreases with increased disease prevalence
      • Total # with disease increases, so TP and FN increase
      • Increased FN = decreased NPV
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11
Q

What are the branches of the celiac trunk:

A

Common hepatic

Splenic

Left gastric

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12
Q

What is the equation for incidence

A
  • Incidence = number of new cases during a specific time period
    • (# of new cases) / (# of people at risk)
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13
Q

Differentiate between precision and accuracy

A
  • Precision
    • Reliability of consistency of a test
    • How reproducible is it?
  • Accuracy
    • Validity of a test
    • How accurate is it?
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14
Q

Describe relative risk and its formula based on this table

A
  • Probability of getting disease in exposed group vs. probability of getting disease in unexposed
    • Calculated from cohort studies
  • Equation:
    • RR = [a/(a+b)] / [c/(c+d)]
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15
Q

Describe odds ration and its formula given this table

A
  • Odds that group with disease (case) was exposed to a risk factor vs. odds that group without disease (control) was exposed
    • Calculated from case-control studies
  • Equation:
    • OR = [(a/c) / (b/d)] = ad/bc
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16
Q

Describe attributable risk and its equation given this table

A
  • Difference in risk among exposed and risk among unexposed
  • Equation:
    • [a/(a+b)] – [c/(c+d)]
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17
Q

Describe absolute risk reduction and its equation given this table

A
  • Looking at how much a beneficial intervention (rather than a risk factor) will affect the risk of disease
    • Risk of those not receiving intervention minus risk of those receiving intervention
  • So:
    • a/(a+b) = people who received intervention and still got disease
    • c/(c+d) = people who did not receive intervention and got the disease
  • Equation:
    • ARR = [c/(c+d)] - [a/(a+b)]
    • THINK: ARR = NPV – PPV
18
Q

Equation for number needed to treat

A
  • 1/ARR
19
Q

Equation for number needed to harm

A

1/AR (attributable risk)

20
Q

Describe relative risk reduction and its equation

A
  • The proportion of risk reduction attributable to the intervention as compared to a control
  • Equation:
    • RRR = 1 – RR
  • Example:
    • If 2% of people who received a flu vaccine develop the flu vs. 8% of unvaccinated people who develop the flu, then RR = 2/8 = 0.25, and RRR = 0.75
21
Q

What is it called when a study population is chosen from the hospital

A

Berkson bias

22
Q

What is non-response bias

A

Nonrespondants meaningfully differ from respondants

23
Q

What is procedure bias?

A
  • Subjects in different groups are not treated the same
24
Q

What is the Pygmalion effect

A
  • Self-fulfilling prophecy
  • Researcher’s belief in treatment changes the outcome
25
Q

What is it called when study subject change their behavior because they know they are being observed

A

Hawthorne effect

26
Q

What is a crossover study

A

When patients serve as their own control

27
Q

In a positive skew, which side is the tail, and rank mean median and mode in order from greatest to least

A
  • Longer tail on the right
  • Mean > median > mode
28
Q

What is the null hypothesis (H0) vs. alternative hypothesis (H1)

A
  • Null hypothesis (H0)
    • States that there is no association between exposure and outcome
  • Alternative hypothesis (H1)
    • States that there is an association between exposure and outcome
29
Q

What does a P-value tell you?

Does a p-value < 0.05 mean you accept or rejec the H0?

A
  • Probability that the study results occurred by chance alone, given that the null hypothesis is true
    • In other words, how compatible is study data with the null hypothesis
  • Small P-value means that it is unlikely that results occurred by chance alone, and thus you can most likely reject the null hypothesis
    • P < 0.05
      • Means you can reject the null hypothesis and accept the alternative hypothesis
      • It means there is a relationship between exposure and outcome
      • “Statistically significant”
30
Q

Differentiate between Type I (alpha) and Type II (beta) error

A
  • Type I error (alpha)
    • False-positive error
    • Incorrect rejection of the null hypothesis
    • Investigator says there is an association between exposure and outcome, when in reality there is none
  • Type II error (beta)
    • False-negative error
    • Incorrect acceptance of the null hypothesis
    • Investigator says there is no association between exposure and outcome, when in reality there is
31
Q

What does “power” refer to?

A

Probability that the test will correctly reject the null hypothesis, when it is indeed false

32
Q

What is the formula for confidence interval

A
  • CI = range from [mean – Z(SEM)] to [mean + Z(SEM)]
    • SEM = standard error of mean
      • SEM = standard deviation / square root of sample size (n)
    • For 90% CI, Z = 1.64
    • For 95% CI, Z = 1.96
    • For 99% CI, Z = 2.58
      • As you increase your confidence level, you widen your confidence interval
      • As you decrease sample size, you widen your confidence interval
33
Q

What is the test used to check for differences between the means of 2 groups with continous variables

A
  • T-test
    • THINK: Tea is meant for 2
34
Q

What is the test used to check for the difference between means of 3 or more groups with continuous variables

A
  • ANOVA:
    • THINK: 3 words in “Analysis Of Variance”
35
Q

What is the test used to check for the difference between 2 or more percentages or proportions of categorical outcomes (not means)

A
  • Chi-square:
    • THINK: Chi-tegorical
36
Q

Which system, HMO or PPO, requires primary care referrals in order to see specialists + only includes “in-network” physicians

A

HMO - Health maintencance organization

  • Preferred Provider Organization (PPO)
    • No gatekeeper to the specialist
    • Patient can see whomever they want; however, the cost is higher for “out-of-network” medical care
    • More expensive than HMO
37
Q

Medicare vs. Medicaid

A

Medicare = elderly + those with certain conditions and end-stage disease

Medicaid = low income

38
Q

Mutation in familal adenomatous polyposis (FAP)

A

Due to mutation of APC tumor suppressor on chromosome 5q

39
Q

What is the defect in Li-Fraumeni syndrome

A

Defective p53 (tumor suppressor) - multiple malignancies at an early age

40
Q

Presentation of tuberous sclerosis

A
  • Triad: Angiofibromas, mental retardation, seizures
  • Other symptoms: Ash-leaf spots, hamartomas of CNS and skin, angiomyolipoma, rhabdomyoma (cardiac tumor)

Review / Wrong Answers (140 decks)

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