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USMLE Step 1 Lecture Notes 2020: Behavioral Science and Social Sciences (2020)

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    USMLE ® Step ! Lecture Notes "#"# Behavioral Science and Social Sciences 00_USMLE_FM.indd 1 7/29/19 8:25 PM

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    USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME), which neither sponsor nor endorse this product. This publication is designed to provide accurate information in regard to the subject matter covered as of its publication date, with the understanding that knowledge and best practice constantly evolve. The publisher is not engaged in rendering medical, legal, accounting, or other professional service. If medical or legal advice or other expert assistance is required, the services of a competent professional should be sought. This publication is not intended for use in clinical practice or the delivery of medical care. To the fullest extent of the law, neither the Publisher nor the Editors assume any liability for any injury and/or damage to persons or property arising out of or related to any use of the material contained in this book. © 2020 by Kaplan, Inc. Published by Kaplan Medical, a division of Kaplan, Inc. 750 Third Avenue New York, NY 10017 !LLRIGHTSRESERVED4HETEXTOFTHISPUBLICATION ORANYPARTTHEREOF MAYNOTBEREPRODUCEDINANY MANNERWHATSOEVERWITHOUTWRITTENPERMISSIONFROMTHEPUBLISHER 10 9 8 7 6 5 4 3 2 1 Course ISBN: 978-1-5062-5472-2 Retail ISBN: 978-1-5062-5470-8 4HISITEMCOMESASASETANDSHOULDNOTBEBROKENOUTANDSOLDSEPARATELY Kaplan Publishing print books are available at special quantity discounts to use for sales promotions, employee premiums, or educational purposes. For more information or to purchase books, please call the Simon & Schuster special sales department at 866-506-1949. 00_USMLE_FM.indd 2 7/29/19 8:25 PM

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    Editors Behavioral Science Alice Akunyili, MD Assistant Professor, Department of Cell Biology and Pharmacology FIU Herbert Wertheim College of Medicine Miami, FL Alina Gonzalez-Mayo, MD Psychiatrist Department of Veterans Administration Bay Pines, FL Mark Tyler-Lloyd, MD, MPH Executive Director of Academics Kaplan Medical New York, NY Basic Science of Patient Safety Ted A. James, MD, MS, FACS Chief, Breast Surgical Oncology Vice Chair, Academic Affairs Department of Surgery Beth Israel Deaconess Medical Center Harvard Medical School Boston, MA Th e editors would like to acknowledge Kevin Schuller, MD, Irfan Sheikh, MD, and Kevin Yang, MD for their contributions. 00_USMLE_FM.indd 3 9/7/18 3:35 PM

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    We want to hear what you think. What do you like or not like about the Notes? Please email us at medfeedback@kaplan.com . 00_USMLE_FM.indd 4 9/7/18 3:35 PM

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    v Table of Contents Part I: Epidemiology and Biostatistics Chapter 1: Epidemiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Chapter 2: Biostatistics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 Part II: Behavioral Science Chapter 3: Developmental Life Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 Chapter 4: Theories of Learning and Behavioral Modification. . . . . . . . . . 65 Chapter 5: Defense Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Chapter 6: Psychological Health and Testing . . . . . . . . . . . . . . . . . . . . . . . . .77 Chapter 7: Substance Use Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 Chapter 8: Sleep and Sleep Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Chapter 9: Psychiatric (DSM-5) Disorders . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Chapter 10: Psychopharmacology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 Chapter 11: Brain Function and Neurocognitive Disorders . . . . . . . . . . . 125 Chapter 12: Ethics, Law, and Physician Behavior . . . . . . . . . . . . . . . . . . . 135 Chapter 13: Health Care Delivery Systems. . . . . . . . . . . . . . . . . . . . . . . . . 157 Part III: Social Sciences Chapter 14: Basic Science of Patient Safety . . . . . . . . . . . . . . . . . . . . . . . . . 161 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193 Additional resources available at www.kaptest.com/usmlebookresources 00_USMLE_FM.indd 5 9/7/18 3:35 PM

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    00_USMLE_FM.indd 6 9/7/18 3:35 PM

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    PART I Epidemiology and Biostatistics 01_USMLE_PartI_Ch01.indd 1 9/8/18 1:45 PM

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    01_USMLE_PartI_Ch01.indd 2 9/8/18 1:45 PM

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    3 Learning Objectives R Answer questions about epidemiologic measures R Use knowledge of screening tests R Explain information related to study designs EPIDEMIOLOGIC MEASURES Epidemiology is the study of the distribution and determinants of health-related states within a population. It refers to the patterns of disease and the factors that in fl uence those patterns. • Endemic : the usual, expected rate of disease over time; the disease is maintained without much variation within a region • Epidemic : occurrence of disease in excess of the expected rate; usually presents in a larger geographic span than endemics ( epidemiology is the study of epidemics) • Pandemic : worldwide epidemic • Epidemic curve : visual description (commonly histogram) of an epi- demic curve is disease cases plotted against time; classic signature of an epidemic is a “spike” in time Th e tools of epidemiology are numbers; the numbers in epidemiology are ratios converted into rates. Th e denominator is key: who is “at risk” for a particular event or disease state. To determine the rate, compare the number of actual cases with the number of potential cases: = = Actual cases Potential cases Numerator Denominator RATE Rates are generally, though not always, per 100,000 persons by the Centers for Disease Control (CDC), but can be per any multiplier. (Vital statistics are usually per 1,000 persons.) A disease may occur in a country at a regular annual rate, which makes it endemic . If there is a sudden rise in the number of cases in a speci fi c month, we say that there is an epidemic . As the disease continues to rise and spread to other countries, it becomes a pandemic . Th us the terminology is related to both the number of cases and its geographical distribution. Epidemiology 1 01_USMLE_PartI_Ch01.indd 3 9/8/18 1:45 PM

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    4 Part I O Epidemiology and Biostatistics Medical Genetics Behavioral Science/Social Sciences Th e graph below represents the incidence of 2 diseases (cases in 100,000). Disease 1 is endemic as the rate of disease is consistent month to month with minor variation in the number of cases. Disease 2 experiences an epidemic in March and April in which the number of cases is in excess of what is expected. January February March April May June July August 3 4 3 4 4 4 3 3 5 5 8 8 5 5 5 5 Figure 1.1 Epidemic vs. Endemic Cases Consider the following scenario. A Japanese farmer begins to sell meat that is infected with salmonella. Within 2 days, hundreds of villagers begin to experi- ence crampy abdominal pain. Th is is an example of an epidemic. Th e sudden rise of salmonella gastroenteritis in this village is much higher than the average incidence for the given time period. Now what if the farmer ships 1,000 pounds of infected beef to other regions of Japan before he realizes what happened? What can one anticipate would happen? Th e answer is there would be no change to the endemic rate of gastroenteritis. Th e farmer is only shipping out 1,000 pounds of beef to a few cities nationwide. Unlike the earlier scenario which addressed the population of a village, this would be the entire nation. Assuming that every person who consumes the beef gets gastroenteritis, that number would not signi fi cantly in- crease the national average of cases and would therefore not signi fi cantly change the incidence of the disease nationwide. Incidence and Prevalence Incidence rate (IR) is the rate at which new events occur in a population. • The numerator is the number of new events that occur in a defined period. • The denominator is the population at risk of experiencing this new event during the same period. Although the data is in 100,000 cases, the variation in disease 1 is still consistent when compared to disease 2. 01_USMLE_PartI_Ch01.indd 4 9/8/18 1:45 PM

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    Chapter 1 O Epidemiology 5 Incidence rate Number of new events in a specified period Number of persons “exposed to risk” of becoming new cases during this period 10 n = × Th e IR includes only new cases of the disease that occurred during the speci fi ed period, not cases that were diagnosed earlier. Th is is especially important when working with infectious diseases such as TB and malaria. If, over the course of a year, 5 men are diagnosed with prostate cancer, out of a total male study population of 200 (with no prostate cancer at the beginning of the study period), the IR of prostate cancer in this population would be 0.025 (or 2,500 per 100,000 men-years of study). Attack rate is the cumulative incidence of infection in a group of people observed over a period of time during an epidemic, usually in relation to food-borne illness. It is measured from the beginning of an outbreak to the end of the outbreak. = Attack rate Number of exposed people infected with the disease Total number of exposed people Attack rate is also called attack ratio ; consider an outbreak of Norwalk virus in which 18 people in separate households become ill. If the population of the community is 1,000, the overall attack rate is × = 18 1,000 100% 1.8%. Figure 1.2 Reported Cases of Hepatitis C in the United States Figure 1.3 Cumulative Incidence 2005–2015 01_USMLE_PartI_Ch01.indd 5 9/8/18 1:45 PM

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    6 Part I O Epidemiology and Biostatistics Medical Genetics Behavioral Science/Social Sciences Prevalence is all persons who experience an event in a population. Th e numerator is all individuals who have an attribute or disease at a particular point in time (or period of time). Th e denominator is the population at risk of having the attribute or disease at that point in time or midway through the period. Pr evalence All cases of a disease at a given point / period Total population “at risk” for being cases at a given point / period n = × 10 Prevalence, in other words, is the proportion of people in a population who have a particular disease at a speci fi ed point in time (or over a speci fi ed period of time). Th e numerator includes both new cases and old cases (people who remained ill during the speci fi ed point or period in time). A case is counted in prevalence until death or recovery occurs. Th is makes prevalence di ff erent from incidence, which includes only new cases in the numerator. Prevalence is most useful for measuring the burden of chronic disease in a population, such as TB, malaria and HIV. For example, the CDC estimated the prevalence of obesity among American adults in 2001 at approximately 20%. Since the number (20%) includes all cases of obesity in the United States, we are talking about prevalence . Point prevalence is useful for comparing disease at di ff erent points in time in order to determine whether an outbreak is occurring. We know that the amount of disease present in a population changes over time, but we may need to know how much of a particular disease is present in a population at a single point in time (“snapshot view”). Perhaps we want to know the prevalence of TB in Community A today. To do that, we need to calculate the point prevalence on a given date. Th e numerator would include all known TB patients who live in Community A that day. Th e denominator would be the population of Community A that day. Period prevalence , on the other hand, is prevalence during a speci fi ed period or span of time. Th e focus is on chronic conditions. In the “prevalence pot ,” incident (or new) cases are monitored over time. New cases join pre-existing cases to make up total prevalence. General Population at Risk Incident Cases Prevalent Cases Recovery Mortality Recovery with Immunity Figure 1-4. Prevalence Pot Prevalent cases leave the prevalence pot in one of 2 ways: recovery or death. Note Prevalence is a measurement of all individuals (new and old) affected by the disease at a particular time, whereas incidence is a measurement of the number of new individuals who contract a disease during a particular period of time. 01_USMLE_PartI_Ch01.indd 6 9/8/18 1:45 PM

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    Chapter 1 O Epidemiology 7 Table 1-1. Incidence and Prevalence What happens if: Incidence Prevalence New effective treatment is initiated no change decrease New effective vaccine gains widespread use decrease decrease Number of persons dying from the condition increases no change decrease Additional Federal research dollars are targeted to a specific condition no change no change Behavioral risk factors are reduced in the population at large decrease decrease Contacts between infected persons and noninfected persons are reduced For airborne infectious disease? For noninfectious disease? decrease decrease no change no change Recovery from the disease is more rapid than it was one year ago no change decrease Long-term survival rates for the disease are increasing no change increase Figure 1-2. Calculating Incidence and Prevalence 1/1/2006 1/1/2007 1 2 3 4 5 6 7 8 10 9 Disease course, if any, for 10 patients Duration Key: Onset Terminal Event Lung Cancer Cases in a Cohort of Heavy Smokers Figure 1-5. Calculating Incidence and Prevalence Note Morbidity rate is the rate of disease in a population at risk (for both incident and prevalent cases), while mortality rate is the rate of death in a population at risk (incident cases only). 01_USMLE_PartI_Ch01.indd 7 9/8/18 1:46 PM

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    8 Part I O Epidemiology and Biostatistics Medical Genetics Behavioral Science/Social Sciences Based on the graph above, calculate the following: • Prevalence of lung cancer from 1/1/2006–1/1/2007 – Number of patients who “had” lung cancer in this time period from the graph: (7) – Number of patients at risk in this time period: (9) [exclude patient #2 who died before the time period] – Prevalence: (7/9) – Type of prevalence: (period prevalence) • Incidence of lung cancer from 1/1/2006–1/1/2007 – Number of patients who developed lung cancer in this time period: (4) – Number of patients at risk in this time period: (6) [exclude patients who were already sick at the start of the time period and those who died before the time period] – Incidence: (4/6) Recall Question Prevalence can be defined as which of the following? A. Number of new events in a specified period over the number of persons at risk of becoming new cases during the same period B. Number of exposed people infected with a disease over the total number of exposed people C. All cases of a disease at a given point over the total population at risk for being cases at the same point D. Number of actual cases over potential cases E. Rate of death in a population at risk Answer: C Crude, Specific, and Standardized Rates Crude rate is the actual measured rate for a whole population , e.g., rate of myocardial infarction for a whole population. Speci fi c rate is the actual measured rate for a subgroup of population , e.g., “age-speci fi c” or “sex-speci fi c” rate. For instance, the rate of myocardial infarction among people age > 65 in the population or the rate of breast cancer among the female population. If you are provided speci fi c rates, you can calculate the crude rate. Th e crude rate of an entire population is a weighted sum of each of the speci fi c rates. Th e weighted speci fi c rates that are added together is calculated in the table below. Note Use caution using the crude rate . Imagine that in a given city, there are a lot of older, retired people—the crude rate of myocardial infarction will appear higher, even though the rate for each age group has not actually changed. 01_USMLE_PartI_Ch01.indd 8 9/8/18 1:46 PM

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