All practice questions

A multicenter prospective cohort study evaluates the safety of a newly approved oral Janus kinase (JAK) inhibitor compared to traditional disease-modifying antirheumatic drugs (DMARDs) for the treatment of severe rheumatoid arthritis. The primary safety outcome is the incidence of unprovoked venous thromboembolism (VTE) over a 5-year follow-up period.

Initial analysis of the data reveals a crude relative risk (RR) of 2.1 (95% CI: 1.6 - 2.8, $p < 0.01$) for VTE in the JAK inhibitor group compared to the traditional DMARD group.

Concerned about baseline genetic differences, the investigators perform a stratified analysis based on the presence or absence of an inherited thrombophilia (e.g., Factor V Leiden mutation). The stratum-specific results are as follows:

- Among patients without inherited thrombophilia: RR = 1.2 (95% CI: 0.8 - 1.6, $p = 0.35$)
- Among patients with inherited thrombophilia: RR = 6.4 (95% CI: 4.5 - 8.9, $p < 0.001$)

Based on the results of the stratified analysis, which of the following epidemiological phenomena best explains the relationship between the JAK inhibitor, inherited thrombophilia, and VTE risk observed in this study?

A $42$-year-old female patient arrives at the outpatient clinic reporting a $12$-month history of unexplained weight gain, severe fatigue, and frequent bruising. Her blood pressure is $155/95\text{ mm Hg}$. Physical examination is notable for central adiposity, facial plethora, and wide, purplish striae on the lower abdomen. She denies taking any medications, including topical, inhaled, or intra-articular corticosteroids. The physician suspects an endogenous endocrine disorder. Arrange the following interventions in the most appropriate chronological sequence for the diagnosis and surgical management of this patient's condition.

A $38$-year-old woman presents to the emergency department with a $6$-hour history of sudden-onset, severe, colicky periumbilical abdominal pain, accompanied by multiple episodes of bilious vomiting. Two years ago, she underwent an uncomplicated laparoscopic Roux-en-Y gastric bypass for morbid obesity. She takes a daily multivitamin. Temperature is $38.4^\circ\text{C}$ ($101.1^\circ\text{F}$), blood pressure is $88/54\text{ mm Hg}$, pulse is $124/\text{min}$, and respirations are $22/\text{min}$. Physical examination reveals a moderately distended abdomen. There is marked tenderness to palpation in the periumbilical region with involuntary guarding and rebound tenderness. Bowel sounds are hypoactive.

Laboratory studies show:
Leukocyte count: $18,500/\text{mm}^3$
Serum bicarbonate: $16\text{ mEq/L}$
Lactic acid: $3.8\text{ mmol/L}$

An upright abdominal radiograph demonstrates multiple dilated loops of small bowel with air-fluid levels and a paucity of colonic gas.

Which of the following is the most appropriate next step in the management of this patient?

Match each clinical presentation of a vascular disorder with its most likely underlying anatomic pathology or mechanism.

A 28-year-old man is brought to the trauma center following a high-speed motorcycle collision. His airway is intact, and his hemodynamics are stabilized with intravenous fluids. A pelvic binder is applied for a complex pelvic ring fracture. Physical examination reveals a scrotal hematoma and fresh blood at the urethral meatus. Digital rectal examination demonstrates a high-riding, nonpalpable prostate. He reports lower abdominal discomfort and a strong urge to void, but has not urinated since the accident. Arrange the following urologic interventions in the most appropriate chronological order for the evaluation and definitive management of this patient's genitourinary injury.

Match each specific orthopedic injury with its most commonly associated acute neurovascular physical exam finding.

An industrial city's health department is planning an intervention to completely eliminate occupational exposure to a specific aerosolized solvent. Historical data show that 30% of the city's adult residents are exposed to this solvent at their workplaces. Extensive cohort studies have demonstrated that the relative risk of developing a severe demyelinating neuropathy in exposed residents compared to unexposed residents is $3.0$. The baseline annual incidence of this neuropathy in the unexposed population is $5$ cases per $1,000$ people.

Assuming the intervention successfully reduces exposure to zero with an immediate effect on risk, and the population size remains stable, how many incident cases of this neuropathy will be prevented per $100,000$ residents in the first year?

Occupational health physicians are investigating the respiratory effects of prolonged exposure to a novel industrial solvent used in paint manufacturing. A longitudinal study follows employees at several facilities over a 10-year period. The study includes $1,500$ floor workers who directly handle the solvent and $4,500$ administrative staff at the same facilities who have no direct solvent exposure. Over the study duration, $120$ of the floor workers and $90$ of the administrative staff are newly diagnosed with adult-onset asthma. Based on these results, what percentage of the asthma cases among the floor workers is theoretically attributable to their solvent exposure?

A primary care physician is evaluating the safety profile of a recently approved weight-loss medication following multiple post-marketing reports of acute pancreatitis. To better understand this potential risk, she reviews a publication in a prominent medical journal. The authors of the paper identified $200$ patients diagnosed with acute pancreatitis and matched them with $400$ healthy patients without pancreatitis from a national health registry. A review of their pharmacy records reveals that $80$ of the patients with pancreatitis had been prescribed the weight-loss medication, whereas $40$ of the healthy patients had been prescribed the same medication. Based on the design of this study, which of the following is the most appropriate measure of association and its calculated value?

A 35-year-old man is brought to the emergency department after sustaining a knife wound to his left medial thigh during an altercation. Paramedics placed a bulky pressure dressing at the scene. His temperature is 37.1°C (98.8°F), blood pressure is 112/72 mm Hg, and heart rate is 108/min. On physical examination, removal of the dressing reveals a 4-cm laceration over the medial thigh with active, pulsatile hemorrhage and a rapidly expanding hematoma. The left foot is cool to the touch, and the left dorsalis pedis and posterior tibial pulses are absent. The right lower extremity has normal 2+ pulses. Which of the following is the most appropriate next step in management?

A $68$-year-old man presents to the emergency department complaining of severe, progressively worsening mid-back pain over the past $2$ weeks. He has a history of advanced prostate cancer treated with androgen deprivation therapy. Over the past $24$ hours, he has developed difficulty walking and states his legs feel "heavy." He also reports an inability to urinate since early this morning. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $142/88\text{ mm Hg}$, and pulse is $88\text{/min}$. On physical examination, there is exquisite point tenderness to palpation over the T10 spinous process. Neurologic examination reveals $3/5$ motor strength in the lower extremities bilaterally. There is decreased sensation to pinprick and temperature below the umbilicus. Deep tendon reflexes are $3+$ at the patellae and ankles, with bilateral upgoing plantar responses. Post-void residual ultrasound shows $550\text{ mL}$ of urine in the bladder. Which of the following is the most appropriate initial step in the management of this patient?

A $44$-year-old woman is evaluated on postoperative day $3$ following a complicated total abdominal hysterectomy for severe endometriosis. She reports new-onset right-sided flank pain and nausea. Her temperature is $38.2^{\circ}\text{C}$ ($100.8^{\circ}\text{F}$). Physical examination reveals right costovertebral angle tenderness. The pelvic surgical drain has abruptly started outputting a high volume of clear, watery fluid. Arrange the following diagnostic and therapeutic steps in the most appropriate sequential order for managing this patient's suspected urologic complication.

A 24-year-old man is brought to the emergency department via ambulance after diving into a shallow lake and striking his head on the bottom. He is conscious but reports an inability to move his arms or legs. His blood pressure is 78/40 mm Hg, heart rate is 52/min, and respiratory rate is 22/min. Oxygen saturation is 94% on room air. He has flaccid paralysis and absent reflexes in all four extremities. Arrange the following steps in the optimal sequence for the management of this patient, from initial presentation to definitive treatment.

An epidemiological review board is evaluating four recent clinical studies for methodological validity. Each study exhibits a distinct analytical or structural flaw that distorts its findings. Review the methodology descriptions below and pair each study with the specific epidemiological phenomenon that best characterizes its flaw.

An unrestrained 24-year-old male driver is transported to the emergency department following a severe front-end motor vehicle collision. Primary survey reveals a hemodynamically stable patient with an isolated right lower extremity injury. The right leg is visibly shortened, adducted, and internally rotated. The patient complains of intense right hip pain and an inability to feel the top of his right foot. Subsequent imaging during his care reveals an incongruent joint space requiring definitive operative intervention. Arrange the following steps in the correct chronological order for the optimal, evidence-based management of this patient's injury.

A 24-year-old man is admitted to the hospital after sustaining a closed midshaft femur fracture in a motor vehicle collision. The fracture is temporarily immobilized in a traction splint, and he is scheduled for operative fixation the following morning. Twelve hours after admission, he develops sudden-onset shortness of breath, confusion, and a new petechial rash over his chest and anterior neck. Vital signs show a temperature of 37.6°C (99.7°F), blood pressure of 122/78 mmHg, pulse of 118/min, and respirations of 26/min. Oxygen saturation is 86% on room air. Auscultation of the lungs reveals scattered bilateral crackles. Which of the following is the most likely diagnosis?

A 46-year-old female patient is referred for surgical evaluation of an asymptomatic neck mass. She noticed the swelling while looking in the mirror two weeks ago. She denies any recent changes in weight, bowel habits, or temperature tolerance. Vital signs are within normal limits. Neck palpation confirms a $2.8\text{-cm}$, firm, well-circumscribed mass localized to the right thyroid lobe. The remainder of the gland is normal, and there is no palpable cervical lymphadenopathy. Laboratory results are as follows:

Thyroid-stimulating hormone (TSH): $0.02\text{ }\mu\text{U/mL}$ (Reference: $0.4-4.0\text{ }\mu\text{U/mL}$)
Free thyroxine (T4): $1.5\text{ ng/dL}$ (Reference: $0.9-1.7\text{ ng/dL}$)
Triiodothyronine (T3): $3.1\text{ pg/mL}$ (Reference: $2.3-4.2\text{ pg/mL}$)

Which of the following is the most appropriate next step in evaluating this patient's condition?

A retrospective cohort study investigates the association between a newly approved hypnotic medication and the incidence of next-day motor vehicle accidents (MVAs) among adults diagnosed with insomnia. The overall crude incidence rate ratio (IRR) for MVAs in patients taking the new medication compared to those not taking any sleep medication is 1.65 (95% CI: 1.45-1.85, p < 0.01).

To evaluate potential third variables, the researchers conduct separate stratified analyses for patient age and concurrent use of diphenhydramine.

Stratification by Age:
- Age > 65 years: IRR = 1.10 (95% CI: 0.90-1.30)
- Age ≤ 65 years: IRR = 1.08 (95% CI: 0.85-1.28)

Stratification by concurrent diphenhydramine use:
- Concurrent use: IRR = 3.10 (95% CI: 2.45-3.80)
- No concurrent use: IRR = 1.12 (95% CI: 0.92-1.35)

Which of the following is the most appropriate next step for analyzing and reporting these study results?

A large population-based study investigates the relationship between daily moderate alcohol consumption and the incidence of lung cancer. The unadjusted analysis shows a relative risk of 2.1 (95% CI: 1.5-2.8) for lung cancer in individuals who consume alcohol daily compared to those who do not. The investigators subsequently stratify the participants based on their history of tobacco smoking. In the stratified analysis, the relative risk of lung cancer is 1.0 (95% CI: 0.8-1.2) among active smokers and 1.0 (95% CI: 0.7-1.3) among non-smokers. Which of the following phenomena best explains the results of the initial unadjusted analysis?

A clinical investigator is reviewing data from a large observational registry of patients with moderate-to-severe plaque psoriasis to assess the safety of a recently introduced interleukin-23 (IL-23) inhibitor. The primary outcome is the rate of severe systemic infections requiring hospitalization. When comparing patients receiving the IL-23 inhibitor to those receiving traditional systemic therapy, the unadjusted relative risk (RR) for severe infection is $2.8$ ($p < 0.05$).

Recognizing that patient populations may differ, the investigator separates the subjects into two subgroups based on concurrent methotrexate use at baseline. Among patients not taking methotrexate, the RR for severe infection is $1.0$ ($p = 0.85$). Among patients actively taking methotrexate, the RR is $1.1$ ($p = 0.62$).

Which of the following strategies, if implemented during the study design phase, would have best prevented the discrepancy between the unadjusted and subgroup risk estimates?