Behavioral Science 2014 Step 1 Review

1. Behavioral Science2014 Step 1 Review Thursday, January 5th Seth Wander sawander@med.miami.edu

2. Behavioral Science Overview • Sample Questions • Study Strategy

3. Behavioral Science • Epidemiology • Biostatistics • Ethics/Doctoring • Psychology/Sociology

4. Study Design Analytic Descriptive Observational Interventional Case Reports Case-Control Clinical Trials Retrospective Rare diseases Odds ratio ** Recall Bias I – safety II – dosing/efficacy III – efficacy v. std of care ** Randomized + double-blind Cross-Sectional Measures prevalence Cohort Prospective Rare exposures Relative risk ** Loss to follow-up bias Test Solutions Identify Problem Identify Risk Factors

5. OR vs. RR Disease a b + - • Odds Ratio: • Odds of having disease in exposed vs. unexposed groups • Via case-control studies • Approx. relative risk if prevalence is low • OR = (a/b) / (c/d) = ad / bc + c d Risk Factor - • Relative Risk: • Likelihood of getting disease following a certain exposure • Via cohort studies • RR = Incidence (exposed) / Incidence (unexposed) • RR = a / (a+b) c / (c+d)

6. Sensitivity vs. Specificity • Sensitivity • Percent of people with disease who test positive • Sens. = a / (a+c) • High value – rules out Disease a b + - + PPV c d Test • Specificity • Percent of people without disease who test negative • Spec. = d / (d+b) • High value – rules in - Sensitivity Specificity • Positive Predictive Value • Percent of positive tests that are true positive • PPV = a / (a+b) Specificity  100% PPV  100% No false positives

7. Sensitivity vs. Specificity: Implications for Screening • Screening = 2° prevention • (+) asymptomatic screen must result in superior outcome (↓ morbidity, mortality) • if not – lead-time bias! Disease (-) Most accurate cutoff Disease (+) False Negatives False Positives Screening Values

8. Sensitivity vs. Specificity: Implications for Screening Disease (-) Disease (+) ↑ Sensitivity ↓ Specificity @100% Sensitivity: No FN, Lots FP ↓ Sensitivity ↑ Specificity @100% Specificity: No FP, Lots FN Screening Values

9. Hypothesis Testing • Null Hypothesis (H0) – no difference exists between disease and risk factor • Type 1 error (α) – identify an effect or difference when none exists (= p value) • Type 2 error (β) – fail to identify an effect when one exists (fail to reject H0) • Power = 1 – β = likelihood of finding a difference when one actually exists (increased with larger sample size). Power 1 - β H1 α Reality H0 β H1 Study Results H0 • Standard Deviation (1SD = 68%, 2SD = 95%, 3SD = 99.7%) • Standard Error = SD / √n (*Always less than SD) • Confidence interval – more informative than p value, larger sample size = smaller CI • p = 0.05 ~ 95% confidence interval, must not include 0

10. Ethics/Doctoring • Key areas: • Informed consent • Advance directives (oral, written, health care proxy) • Confidentiality • Medicare/Medicaid • Clinical situations and decision making (eg. end of life care, patient autonomy, etc).

11. Sleep Stages • Awake/alert (Beta waves) • Stage 1 – light sleep (alpha, theta) • Stage 2 – deeper sleep (increased theta, sleep spindles) • Stage 3-4 – deepest sleep, slow wave (delta) • Sleepwalking, night terrors, enuresis occurs here • REM – dreaming, loss of motor tone, memory processing, etc. (“paradoxical sleep”) • Duration increases throughout the night • Ach is the key NT in REM sleep • Key pharm. that decreases REM sleep: • Barbiturates • Alcohol • Phenothiazines • MAOi • ** REM rebound upon withdrawl!

12. 1) A large group of individuals are followed over 10 years. Every year, it is determined who develops heart disease and who does not. What type of study is this? A) Cross-Sectional B) Cohort C) Case-Control D) Case Report

13. 2) A man has flashbacks about his girlfriend’s death 2 months ago following a hit-and-run accident. He often cries and wishes for the death of the culprit. What is the diagnosis? A) Depression B) Bipolar Disorder C) Normal Bereavement D) Seasonal Affective Disorder

14. 3) You enter a treatment room to begin a physical exam on a patient. Prior to the exam, the patient states that they find you attractive. What is the most appropriate response? A) End the exam and refer the patient to another physician B) Begin seeing the patient socially C) Utilize a chaperone and perform the exam D) Ignore the patient’s comment

15. 4) A study is performed in which a large group of individuals are queried as to whether or not they have high blood pressure. They are subsequently asked about their exposure to a certain type of preservative frequently used in several food types. This study is particularly prone to what type of bias? A) Recall bias B) Lead-time bias C) Loss-to-follow-up bias D) Sampling bias

16. 5) A new test is devised to identify the presence of an asymptomatic disease. 200 people are tested for the disease. There are 60 true positives and 20 false positives. What is the positive predictive value for this new test? A) 100% B) 75% C) 30% D) 25%

17. 6) Which of the following is a common clinical change that occurs in the elderly? A) Decreased incidence of depression B) Improved immune response C) Decreased fat content D) Decreased REM sleep E) Improved pulmonary function

18. 7) A diagnostic test is available with an extremely high sensitivity but a relatively low specificity. Assuming a normal population distribution, which of the following accurately describes the usefulness of this test? A) There are a large number of false negatives and false positives B) There are very few false negatives or false positives C) There are a large number of false positives, but very few false negatives D) There are no false positives

19. 8) Which of the following accurately reflects the difference between prevalence and incidence? A) Incidence refers to the total number of cases in a population, while prevalence refers to new cases only B) Prevalence is equal to incidence for acute diseases C) Incidence is greater than prevalence for common diseases D) Incidence is approximately equal to prevalence multiplied by disease duration

20. 9) Following an experiment, two groups that experienced different treatments were found to manifest identical endpoints. The conclusion of the study was that no difference between these treatments existed. If, in fact, there was a difference but it was not identified in this study, what type of error has been made? A) Standard error B) Type I error C) Type II error D) Selection bias

21. 10) Following a private discussion with a patient you encounter several members of the patient’s immediate family in the hallway. They pull you aside and ask to speak privately with you about the patient’s current state and potential treatment options. Which of the following is the appropriate response? A) Discuss all the latest test results and seek their opinion regarding treatment options B) Ignore them entirely C) Discuss only minor aspects of the patient’s care with them D) Do not discuss patient information with family members without prior express permission from the patient