USMLE Biostatics Question Base

A 48-year-old man is brought to the psychiatric emergency department after an attempted suicide. He claims to hear voices telling him to kill himself. The patient’s family notes that he has been on several different kinds of antipsychotic medications, with no improvement of his symptoms. The attending psychiatrist places the patient on a new medication and admits him. One week after therapy has begun, a routine blood test reveals profound depletion of polymorphonuclear leukocytes. Which of the following drugs is most likely responsible for these symptoms?

After a bout of aseptic meningitis, a patient is unable to recall a surgical procedure he underwent before the infection. He is, however, able to register and recall present events. The patient most likely has which of the following conditions?

A 9-year-old boy has been caught stealing the lunches of his classmates on three separate occasions. He sleeps in class and usually does not participate in the educational process. The boy is small for his age and generally does not interact with his classmates except when they hit him. When his fourth-grade teacher tries to contact the parents for a conference, she discovers that they have no telephone and the address given to the school is a post office box. Which of the following is most likely cause of this child’s behaviour?

A city has a population of 250,000. Of these, 10,000 have disease X, which is incurable. There are 1,000 new cases and 400 deaths each year from this disease. There are 2,500 deaths per year from all causes. The prevalence of this disease is given by

A 64-year-old man is brought to the emergency department by the police after he is discovered wandering in a local park late one evening. When examined, the man is able to give his name but appears confused and asks repeatedly where he is and how he got there. He is, however, able to accurately answer questions about the current year and president. Level of consciousness and attention span are both normal on the mental status exam. Subsequent investigation shows that the man was reported missing several days ago by his relatives who live some 300 miles away in a different city. Which of the following is the most likely preliminary diagnosis?

A 30-year-old heterosexual man repeatedly cross-dresses to achieve sexual excitement but is content with his biologic gender. Which of the following is the most likely diagnosis?

In a medical class of 147 students, the distribution of scores on a biochemistry final examination has a mean equal to 67, is median equal to 76, a mode equal to 80, a standard deviation equal to 5.5, and a variance equal to 30.25. Three students were unable to take the test on the scheduled date and were given a different form of the exam I week later. Which parameter is most likely to be the least biased estimator of central tendency for this distribution of biochemistry test scores?

A 27-year-old man believes that he lives on a planet circling the star Alpha Centauri. His speech is rambling, he giggles frequently at inappropriate times, and he does not make sense when talking with others, He exhibits purposeful behaviors that do not accomplish an end and often “hears voices.” The first episode of this behavior occurred when he was 18 years old. Which of the following is the most likely diagnosis?

A 5-year-old boy is taken to a dermatologist to remove a suspicious-looking lesion from his back. He is extremely afraid of receiving an injection and of the procedure in general. The best way to alter his pain perception threshold would be to

A 64-year-old woman is hospitalized for an acute exacerbation of schizophrenia. The medications that she is prescribed cause some immediate adverse effects, but she tolerates them and continues to be compliant. A few years pass and she begins to develop neurological abnormalities. These include involuntary, repetitive movement of the lips and tongue, as well as of her trunk and extremities. Which of the following medications should now be prescribed to this patient?

A 27-year-old woman reveals to her gynecologist that her last three miscarriages were caused by spousal abuse while she was pregnant. Her husband also abuses her at times when she is not pregnant. When the husband is confronted with this report, he does not deny it. The husband’s behavior is most likely explained by which of the following?

A 25-year-old actress tends to behave seductively and with exaggerated charm to obtain continuous attention. She often puts on an overdramatized display of emotion but lacks genuine deep feelings. She craves control in her interpersonal relationships, often causing them to disintegrate. This patient most likely has which of the following personality disorders?

A 57-year-old woman is diagnosed with pancreatic cancer. After a complete workup, she is informed that she has between 6 months and 1 year to live. Kubler-Ross’s stages of dying are listed below:

1. Acceptance
2. Anger
3. Bargaining
4. Denial
5. Sadness/depression

Which of the following correctly expresses the order in which she will most likely experience these stages?

A 32-year-old man reports difficulty maintaining an erection during intercourse with his wife. This has developed gradually over the past 3 years. He had experienced no such difficulty prior to marriage. He reports full morning erections with wakening. He had a sexual experience on a recent business trip and noted no difficulty on that occasion. He looks embarrassed as he gives his history. Although there is no evidence for anger when speaking about his wife, evidence of anxiety is prominent. Which of the following is the most likely diagnosis?

An 88-year-old man complaining of abdominal pain enters the emergency department with his wife. A mini-mental status exam reveals pronounced forgetfulness and confusion. The patient is discovered to have acute appendicitis requiring immediate surgery. He is unable to understand the situation and cannot provide informed consent. Which of the billowing huffier actions must the physician take?

A 37-year-old man is referred to a psychiatrist for evaluation for sexual reassignment. Ile states that from as early as he can remember, he has been sexually attracted only to other men. However, he always feels enormous guilt after a sexual liaison with a man. While he has functioned adequately with women, he has no emotional or physical affinity for them. I le is requesting sexual reassignment because he wants to have a husband and a normal heterosexual life. Which of the following is the most likely diagnosis?

An 18-month-old child is brought to a pediatrician by his 17-year-old mother because the child weighs only 14 lb. His birth weight was 7.25 lb. The mother states the infant never “ate right.” Observation reveals a hypokinetic child who is dull and listless with a poverty of spontaneous activity. He appears sad and miserable but visually tracks the physician. Examination suggests malnourishment. His muscle tone is poor. and his skin is cool and more mottled than expected. There are no signs of physical trauma. The mother spends a great deal of time talking to the pediatrician about her own problems. Which of the following is the most likely diagnosis?

A 43-year-old man is sitting on the examining table with his shoulders slumped. His head and eyes are downcast. His eyes are red. He looks up slowly and, after a deep sigh, says “I am sorry to bother you, Doctor, but I have to talk to someone. I have been so discouraged and so depressed for over 2 years, and 1 can’t take it anymore” Which of the following is the most likely diagnosis?

A 30-year-old woman sees a psychiatrist three times a week. She is having an extremely hard time dealing with a death in her family, but at the moment she is concerned about the length of time that she has been feeling this way. She is somewhat comforted when the psychiatrist tells her that the grief and bereavement process typically takes the longest to resolve after the death of this family member. Which of the following family members most likely died?

A 73-year-old woman has difficulty concentrating and demonstrates some mild immediate-memory problems. She has a poor appetite and has lost 24 lb in 6 weeks. She resists participation in recreational activities, and she wakes up at 4:00 AN everyday and is unable to get back to sleep. Her condition is worsening on a daily basis. Which of the following is the most likely diagnosis?

A pharmaceutical researcher is examining the ulcerogenic potential of a new nonsteroidal anti-inflammatory drug. He gives 20 rats a single subcutaneous injection of the drug every day for 1 week, and gives a similarly matched group of 20 animals daily saline injections for 1 week. Twenty-four hours after the final injection, the investigator sacrifices the rats, removes their stomachs, and examines them to determine whether any ulcers were produced. He obtains the following data:

Which of the following tests would be most appropriate for determining whether administration of the drug increased the incidence of stomach ulcers?

A 29-year-old man reveals to his psychiatrist that he has been hearing voices telling him to kill his girlfriend. Which of the following principles requires that the physician inform the girlfriend that she is in danger?

A disgruntled surgical technician who is being treated for depression with phenelzine takes an analgesic he found on the drug cart in the surgical suite. Several hours later, he arrives at the emergency department in a delirious state and has a temperature of 105.0 F. Soon after his arrival, he begins having convulsions. Which of the following analgesics did he most likely take?

A child psychiatrist would like to evaluate the intellectual ability of a 3-year-old patient. Which of the following is the most appropriate test for him to use?

The parents of a 7-year-old boy divorce. The boy lives with the mother and sees his father every other weekend. During these visits, the boy is alternately sullen and angry with the father, but when it is time to return home, he clings to the father and cries in a desperate manner while saying “I’m sorry! I want you and mom to live together again.” Which of the following is the most helpful statement that the father can make to the son?

At the Academy Awards ceremony, a very successful movie star becomes loud and agitated when she does not win in the category in which she had been nominated. She states to those around her that her performance was superior to that of the winner, that the Academy clearly does not appreciate her genius and acting skills, and that there should be a separate category for persons of her extraordinary abilities. She further states that she did not win because the Academy members are envious of her skills. This person most likely has which of the following disorders?

A group of patients with lung cancer is matched to a group of patients without lung cancer. Their smoking habits over the course of their lives is compared. On the basis of this information, researchers compute the rate of lung cancer in patients who smoke versus those who never smoked. This is an example of a

A research study investigating the effects of three variables (age, sex, and ethnicity) on the efficacy of a new malaria vaccine reports a significant (p <0.001) analysis of variance (ANOVA) result. There is a significant two-way interaction. Regarding these variables, which of the following is the best interpretation of these results?

A 42-year-old man has just been informed that he has poorly differentiated small cell carcinoma of the lung. When asked whether he understands the serious nature of his illness, the patient proceeds to tell his physician how excited he is about renovating his home. Which of the following defense mechanisms is this patient exhibiting?

A new test is being designed to diagnose cervical Chlamydia trachomatis infections. Which of the following epidemiological parameters would directly affect the Positive predictive value of this test?

A 91-year-old woman with Alzheimer disease is hospitalised because of multiple injuries caused by elder abuse. She has a tilled humerus and a healing burn mark on her forearm. She has ecchymoses in various stages of resolution on her upper arms, buttocks, back, and less. Which of the following best describes the attributes of the individual who committed this abuse?

A 44-year-old man has completed college, has had a good work history, and has never had difficulty with the authorities. However, he has few friends and attends meetings of persons who share telepathic interests and “abilities.” When his cow8rkers attempt to talk to him about these meetings, he is quiet and vague regarding what is done at the meetings and where they are held. His only dose associations are with his relatives. He is more likely than the average person to have a relative with a diagnosis of

A 52-year-old white man who had been found wandering the streets is brought into the hospital by police. On initial physical examination, his motor behavior is notable for bradykinesia and a 4- to 6-Hz hand tremor at rest. He is kept under observation in the psychiatric ward but is not medicated. Over the next few days, his motor symptoms start to abate, but he becomes increasingly paranoid and confused and insists that he is the President of the United States. Which of the following conditions best describes the patient at the time of admission?

A 60-year-old man has had difficulty falling asleep for the past several weeks and asks his physician for advice. The patient has no underlying psychopathology. Which of the following is the most appropriate non-pharmaceutical treatment for this patient?

Medical students at a major teaching hospital are routinely assigned to observe obstetric patients and to assist during delivery. When a male medical student introduces himself to an obstetric patient, the patient becomes agitated and requests that no students be present during her delivery. The patient had been informed, prior to admission, that this was a teaching hospital and that a student would be assigned to her case. When informed of the patient’s refusal, the attending physician in charge should

Eight research scientists are brought into the hospital by paramedics. The scientists are experiencing diaphoresis, blurred vision, palpitations, and hallucinations with brilliant colors. Police suspect that the coffee at their lab meeting was laced with a psychoactive substance. Which of the following substances is most likely to be found in the coffee pot?

A patient comes to the physician for a periodic health maintenance examination. The patient has no specific complaints at this time; however, many friends of this patient have recently been diagnosed with HIV, and the patient is very concerned about contracting the disease. The patient reveals his/her sexual orientation and admits to having unprotected sex. The physician reassures the patient that s/he is within the sexually active group with the lowest risk of contracting HIV. Which of the following most likely describes this patient?

A 27-year-old, rather plain-appearing woman, fabricates a story that she was raped in the restroom at her child’s school. She inflicts wounds on her body with a pair of scissors, gives herself a mild concussion by hitting her head on the sink, and describes the attacker and the episode in great detail when the emergency care persons arrive and take her to the hospital. Later she admits that there was no attack and that she produced the signs and symptoms herself. She states that she did it to get more attention from her husband. If she has a personality disorder, the most likely diagnosis would be

A child is in psychotherapy that is financially supported by the parents. Which of the following is the best way to avoid breaching the child’s confidentiality while the parents are legally responsible for the child’s welfare?

A neuropsychologist is studying the effects of drug A and drug It on cognitive performance in Alzheimer patients. 1k administers a memory test to two groups of subjects (those taking drug A and those taking drug B) and compares their mean scores. Which of the following statistical tests would be most appropriate for this purpose?

A second-year medical student falls asleep during a lecture. The instructor observes that the instant the student falls asleep, his eyes make rapid lateral movements under his closed eyelids. Which of the following is the most likely diagnosis?

A previously healthy 32-year-old woman comes to the physician for a routine examination. She reports that she has been “very down” and has had trouble sleeping. She has also lost weight, even though she has not been trying to diet. For the last few months, she has been staying home at night and on weekends, despite friends’ efforts to take her out. Physical examination and laboratory studies are normal. The physician recommends cognitive therapy. This therapy is based on the theory that her disorder is caused by

In a study, a group of people are exposed to an environmental toxin but are not treated. Instead, they are observed over time on a standard set of measures to ascertain the potential effects of the toxin. This type of study design is called

A man is distraught because he has to sell his car and move from his house to a one-room apartment. He no longer has extra spending money, and he has difficulty covering his weekly grocery bills. He cannot afford to eat out in restaurants and has been unable to buy new clothes in years. He used to have enough money to cover all of these expenses. Which of the following is the most likely reason for this “downward move” in socioeconomic status?

A husband comes to the family physician to discuss his wife’s sleep behavior. During the past 2 months, she has been kicking and hitting him in her sleep. She does not remember these occurrences the next morning or if he wakens her in the night. He is concerned that she has developed some anger toward him, which she is unwilling or unable to discuss. Which of the following is the most likely diagnosis?

A 60-year-old man hospitalized with metastatic colon cancer signs a DNA order. This means that the medical staff treating him is required to

A patient comes to the physician because of sexual dysfunction. After a thorough evaluation and a trial of conservative therapy, the patient is scheduled for surgery. Which of the following is the most likely cause of this patient’s sexual dysfunction?

A group of researchers mistakenly concludes from a poorly designed experiment that acetaminophen cures the common cold. These researchers have committed which of the following types of error?

A girl is brought to the pediatrician for a well-child visit. The mother reports no problems with her daughter. Physical examination is unremarkable, and the child is up to date on her immunizations. Further evaluation reveals that the girl understands that the volume of a liquid poured out of a narrow glass remains the same when poured into a wider glass. This child is at which of Piaget’s stages of intellectual development?

In a restaurant, the parents of a 4-year-old child are talking with each other and not with the child. The child first says “Mommy”; when the mother does not respond, the intensity of the word “Mommy” increases. The child then begins to drop her eating utensils. When the parents still do not respond, the child knocks over her glass of milk. The parents then scold the child and busy themselves cleaning up the spilled milk and get. ting more for the child. This scenario is repeated three times before the parents angrily take the child from the restaurant. This entire scene is an example of which of the following types of learning?