All practice questions

A local public health department is investigating a community outbreak of a highly contagious viral respiratory illness originating from a single elementary school. Initial contact tracing identifies $20$ primary cases, all of whom are students at the school. These $20$ children live in $20$ distinct households. Demographic analysis reveals that the total number of individuals residing in these $20$ households is $105$. Medical record review confirms that among the household members who are not primary cases, $15$ individuals have documented immunity due to recent vaccination and are considered non-susceptible. During the recognized incubation period following exposure to the primary cases, $14$ new cases of the identical respiratory illness develop among the household members.

What is the secondary attack rate (in percentage) of this viral illness among the susceptible household contacts?

A medical center conducts a randomized controlled trial comparing a newly developed lipid-lowering medication to a standard statin therapy in 150 patients with familial hypercholesterolemia. After six months, the investigators report that the new medication reduces low-density lipoprotein (LDL) cholesterol significantly more than the standard therapy ($p = 0.04$). Based on these results, the medication is approved and widely prescribed at the institution. Two years later, a well-powered, multi-center trial with 5,000 patients reveals no statistically significant difference in LDL reduction between the two treatments. Assuming the large-scale trial's conclusion represents the true relationship, which of the following best describes the statistical phenomenon that most likely occurred in the initial study?

Match each clinical scenario of a newly admitted patient to the most appropriate initial infection control isolation tier required.

An inpatient medical team is evaluating a 47-year-old woman who recently presented with acute kidney injury due to a severe systemic lupus erythematosus flare. Laboratory studies reveal a blood urea nitrogen of 92 mg/dL, a serum creatinine of 6.8 mg/dL, and a potassium level of 5.1 mEq/L. Her electrocardiogram is normal, and she is currently hemodynamically stable. The nephrology service recommends urgent initiation of hemodialysis. The patient is awake, alert, and oriented to person, place, and time. She scores 29/30 on a standardized cognitive screening examination. During the interview, she communicates clearly and states she understands that the medical team believes her kidneys are failing and that dialysis is recommended to prevent fatal complications. However, she adamantly refuses the procedure. When asked to explain her reasoning, she states, "My kidneys are perfectly healthy. The doctors are lying to me so they can hook me up to that machine and extract my rare antibodies to sell to researchers." Which of the following is the most appropriate next step in management?

A 38-year-old woman with a known history of bipolar disorder, currently in a severe manic episode with psychotic features, is evaluated in the emergency department for a deep, contaminated laceration on her right forearm. The surgical team recommends urgent exploration and repair to prevent permanent nerve damage and severe infection. She adamantly refuses the surgery, stating that she has "superhuman healing abilities" and that the wound will magically close by tomorrow. She is highly agitated, pacing the room, and cannot focus on the conversation. The primary team must determine how to proceed with her care ethically and legally.

Arrange the following steps in the most appropriate sequential order for evaluating this patient's decision-making capacity and determining the subsequent course of action.

An infection control physician is reviewing the medical record of a patient who recently developed a fever in the intensive care unit. The patient is a 62-year-old male on postoperative day 8 following an extensive bowel resection. He has been receiving total parenteral nutrition through a multi-lumen central venous catheter. Over the past 24 hours, his temperature has risen to 38.9°C (102.0°F) with a pulse of 110/min. The catheter site appears clean and intact. Suspecting a catheter-related infection, the primary team drew paired blood cultures simultaneously from the central line and a peripheral vein. Which of the following laboratory outcomes establishes the central venous catheter as the definitive source of the bacteremia?

An attending physician is finalizing discharge paperwork for a 62-year-old woman who recently suffered a non-ST-segment elevation myocardial infarction. During the hospitalization, the patient's daily medication regimen was significantly modified: her pre-admission dose of metoprolol succinate was increased, ticagrelor and aspirin were initiated, and her daily over-the-counter ibuprofen was explicitly discontinued due to a heightened risk of gastrointestinal bleeding. The physician hands the patient a printed list of her new prescriptions and briefly explains that she should take the new blood thinners daily. Three weeks later, the patient is readmitted with melena and symptomatic anemia. She reports taking her new medications faithfully, alongside all her 'usual at-home pills,' which includes the ibuprofen. Which of the following transition-of-care strategies is the most appropriate systemic approach to prevent this patient's adverse event?

A 55-year-old man presents to the emergency department with sudden-onset, tearing chest pain radiating to his back. The physician suspects acute aortic dissection. Based on his history, physical examination, and initial chest x-ray findings, the pre-test probability of an acute aortic dissection is estimated to be $20\%$. The physician orders a rapid D-dimer assay, which for this specific cutoff has a reported sensitivity of $80\%$ and a specificity of $95\%$ for aortic dissection in this clinical setting. The patient's D-dimer result returns negative.

Based on these test characteristics, what is the probability (expressed as a percentage) that this patient actually has an acute aortic dissection despite the negative test result?

A 34-year-old man comes to the clinic for a routine follow-up regarding his human immunodeficiency virus (HIV) infection. He was diagnosed 4 years ago but has been nonadherent to his antiretroviral therapy for the past 9 months due to a loss of insurance. Recent laboratory studies show a CD4 cell count of 180 cells/mm³ and an HIV viral load of 350,000 copies/mL. During the encounter, the patient mentions that he recently moved in with a new female partner who is currently 10 weeks pregnant. He states that they engage in unprotected sexual intercourse. The physician extensively counsels the patient on the high risk of transmitting the virus to his partner and the subsequent risk of perinatal transmission, strongly encouraging him to disclose his status. The patient adamantly refuses, stating, "I can't tell her; she will leave me. You are my doctor, so my medical information is strictly confidential." Which of the following is the most appropriate next step in management?

A 26-year-old male medical student is evaluating a 55-year-old man who was admitted to the hospital 1 day ago with a 3-week history of productive cough, low-grade fever, night sweats, and a 5-kg (11-lb) weight loss. The patient was initially placed on standard and droplet precautions for a suspected atypical bacterial respiratory infection. During the physical examination, the patient experiences paroxysms of coughing while the student is auscultating his lungs. The student is wearing a standard surgical mask, gown, and gloves. Later that afternoon, the patient's sputum acid-fast bacilli smear returns positive, and he is immediately transitioned to an airborne infection isolation room. The student is asymptomatic. A review of the student's occupational health records shows a negative interferon-gamma release assay (IGRA) documented 2 months ago during annual screening. Which of the following is the most appropriate next step in the management of this student?

A multicenter gastroenterology consortium establishes a prospective registry to evaluate the risk of cholangiocarcinoma in patients with primary sclerosing cholangitis. On January 1, 2020, the team screens 258 patients and excludes 4 who already have evidence of malignancy. The remaining 254 disease-free patients are followed until December 31, 2024.

During this exact 5-year observation period, the following events are recorded among the enrolled cohort:
- 30 patients are diagnosed with cholangiocarcinoma exactly 24 months after enrollment.
- 50 patients are lost to follow-up exactly 36 months after enrollment, with no evidence of malignancy prior to that point.
- 20 patients die from unrelated causes exactly 12 months after enrollment, without developing the cancer.
- The remaining patients complete the full 5-year follow-up period without developing the disease.

Assuming no other patients enter or leave the study, what is the incidence rate of cholangiocarcinoma in this cohort, expressed as cases per $1,000$ person-years?

A 29-year-old woman at 18 weeks gestation presents to the emergency department with a displaced fracture of her left radius and periorbital ecchymosis. After the physician establishes a private environment and builds rapport, the patient tearfully discloses that her husband caused the injuries by striking her with his fists and twisting her arm during a severe argument. She demonstrates clear, intact decision-making capacity. She insists that the physician must not contact the police or any state authorities, explaining that her husband has threatened to kill her if she tells anyone. Which of the following is the most appropriate legally and ethically sound action?

A 72-year-old man with advanced heart failure is admitted to the intensive care unit with cardiogenic shock. His mentation is significantly altered due to cerebral hypoperfusion; he is disoriented to time and place, cannot sustain attention, and is unable to comprehend his medical condition or prognosis. The critical care team believes that further invasive interventions would be medically futile and recommends transitioning to comfort-focused care. He has no written advance directive or designated healthcare proxy. His wife of 40 years is present and agrees with the transition to palliative care, stating, "He told me many times he wouldn't want to suffer on machines." Shortly after, the patient's adult son from a previous marriage arrives. He demands that all life-sustaining measures be continued and insists that a judge must be involved to officially declare his father incompetent before the care plan can be changed. Which of the following is the most appropriate response to the son's demand?

Match each healthcare payment and delivery model with the clinical operational scenario that best describes its mechanism of reimbursement and risk distribution.

An attending physician is evaluating four different patients to determine their medical decision-making capacity and the appropriate next ethical or legal steps. Match each clinical scenario with the most accurate capacity determination and clinical action.

A 52-year-old man presents to an urgent care clinic with progressive right calf swelling and pain. The physician strongly suspects a deep vein thrombosis (DVT) and performs a point-of-care D-dimer test, which returns positive. The facility's only ultrasound machine is currently undergoing unexpected maintenance. The physician decides to administer a stat dose of rivaroxaban and discharges the patient to home, instructing him to get a venous ultrasound at a neighboring imaging center the following morning. During this encounter, the physician fails to reconcile the patient's home medications, overlooking his chronic use of carbamazepine, a potent CYP3A4 inducer that significantly decreases rivaroxaban efficacy.

Six hours later, the patient is brought to the local emergency department with sudden, severe dyspnea and hypoxia, ultimately requiring systemic thrombolysis for a massive pulmonary embolism.

An institutional root cause analysis determines several factors led to this outcome: the failure to fully evaluate the leg pain, the overlooked pharmacokinetic interaction, the unsafe discharge plan, and the facility's complete lack of a contingency protocol for managing acute vascular risks during imaging equipment downtime.

Which of the following best categorizes the facility's lack of a contingency protocol?

A pharmacovigilance committee is investigating a potential pharmacological trigger for acute angle-closure glaucoma (AACG). Recent post-marketing surveillance reports suggest that the ingestion of over-the-counter oral sympathomimetic decongestants may precipitate an acute attack of AACG within 24 hours of use. AACG is a rare, vision-threatening emergency strongly associated with static, individualized anatomical risk factors—such as a narrow iridocorneal angle and a short axial length—which are difficult to systematically measure across large populations. The investigators aim to quantify the short-term risk associated with decongestant use while completely eliminating the confounding effects of these unmeasured, static between-person differences.

Which of the following is the most appropriate study design for this investigation?

Match each clinical scenario involving suspected physician impairment, misconduct, or cognitive decline with the most legally and ethically appropriate immediate intervention or reporting pathway.

A pharmaceutical company is designing a randomized controlled trial to evaluate the efficacy of a novel antihypertensive medication compared to a placebo. The research team is reviewing the statistical framework for the study. Match each statistical concept with its corresponding clinical description in the context of this trial.

A new self-administered screening questionnaire for generalized anxiety disorder (GAD) is validated in a specialized psychiatric outpatient clinic where the prevalence of GAD is $40\%$. In this high-prevalence setting, the questionnaire has a sensitivity of $90\%$, a specificity of $80\%$, a positive predictive value (PPV) of $75\%$, and a negative predictive value (NPV) of $92\%$.

Administrators at a large primary care network decide to use this questionnaire for routine screening in their general medicine clinics. Epidemiological data confirms that the prevalence of GAD in this general practice population is $10\%$. Assuming the intrinsic test characteristics (sensitivity and specificity) of the screening tool remain identical, which of the following describes the expected change in the predictive values when the questionnaire is used in the primary care clinics rather than the psychiatric clinic?