Behavioral Science - UWorld

Question 1

A payer pays a fixed predetermined fee for all healthcare services required by a patient

Answer 1

Capitation. This is the concept behind HMOs.

Question 2

Positively vs. negatively skewed Bell curve

Answer 2

Positively skewed = most scores are on the lower end and mean > median > mode

Negatively skewed = most scores are on the high end and mode > median > mean

Question 3

Attrition bias

Answer 3

Study subjects are assigned to groups in a non-random fashion

Question 4

Cancers with highest incidence/mortality in US men and women

Answer 4

Men incidence: prostate > lung > colon
Men mortality: lung > prostate > colon

Women incidence: breast > lung > colon
Women mortality: lung > breast > colon

Question 5

Study’s ability to detect a difference when one exists

Answer 5

Power = 1 - beta, where beta = the likelihood of making a type II error (accepting the null when it’s actually false…i.e. say there isn’t a difference when there truly is). Thus, power is the likelihood of rejecting the null when there really is a difference.

Question 6

Type I error

Answer 6

Reject the null when it’s actually true…i.e. say there is a difference when there’s truly not.

Question 7

Odds ratio

Answer 7

AD/BC. Only use in case-control studies because you do not follow patients over time and cannot assess risk.

Question 8

A new study is developed for prostate cancer that is negative in 95% of patients who do not have cancer. If the test is used on 8 blood samples from patients without prostate cancer, what is the probability of getting one false-positive result?

Answer 8

The probability that one sample tests positive = 1 - (0.95^8) because you are testing the probability of a series of independent events, which requires mulitplication of the probability of each individual event.

Question 9

Relative risk

Answer 9

[a/(a+b)] / [c/(c+d)]

Question 10

How do you relate carrier, disease and gene frequency for an autosomal recessive disease with only two possible alleles?

Answer 10

Hardy-Weinberg Principle: p^2 + 2pq + q^2 = 1

• p = homozygous dominant individuals
• 2pq = carrier frequency
• q = homozygous recessive individuals (q^2 = disease frequency for autosomal recessive diseases)

***It is important to remember that you only need one value, p or q, and then you can calculate the frequency because there are only two alleles for the disease. Plug your known value into the Hardy-Weinberg equation, then substitute that value for (p+q)=1 and solve for the other variable, then plug it back into the Hardy-Weinberg Principle and it will give you that genotype frequency in the general population.

Question 11

Absolute risk reduction

Answer 11

Event rate in control group - Event rate in treatment group

Question 12

Relative risk reduction

Answer 12

Absolute relative risk / control rate.

Question 13

Number needed to treat

Answer 13

1/Absolute risk reduction or 1/(control rate - treatment rate)

Question 14

When does the OR approach RR?

Answer 14

When disease incidence is low

Question 15

Number needed to harm

Answer 15

1/Attributable Risk (treatment group event rate - control group event rate)

Question 16

Benzo with short t1/2 that can be used for short-term insomnia treatment in patients that cannot tolerate daytime sleepiness

Answer 16

Triazolam

Question 17

Attributable risk percent

Answer 17

100 x [(exposed risk) - (unexposed risk)]/exposed risk

or more simply

100 x (RR - 1)/RR

Question 18

Hypomanic vs. manic

Answer 18

Hypomanic = no psychosis, less severe, preserved functional status

Manic = more severe, > 1 week with functional impairment