Keeping an Open Mind

A CLINICAL PROBLEM-SOLVING article by Nasia Safdar from University of Wisconsin–Madison School of Medicine.
A 67-year-old man presented with a 3-month history of fatigue and fever. He had undergone heart transplantation 6 years earlier for idiopathic cardiomyopathy. During the previous several weeks, the patient had been seen by his regular physicians and was initially prescribed oral amoxicillin followed by levofloxacin for nasal stuffiness due to presumed sinusitis, with no change in his fever. Evaluation during this time included a complete blood count, liver-function tests, and routine serum chemical analyses. Results were normal. Serum polymerase-chain-reaction assays for CMV and Epstein–Barr virus were negative. A serum cryptococcal-antigen test was negative. Chest radiography revealed no infiltrate. A CT of the head showed mild hydrocephalus but no focal lesions.
His fever persisted and profound apathy developed. His treating physicians diagnosed depression.
How can clinicians avoid mistakenly ruling out a disease when a highly sensitive test is negative? It is important to remember that no test is 100% sensitive and that technical problems and factors specific to the organism or patient may result in a false negative test. This case highlights another important question: When should we begin treatment for a disease that is suspected but not yet verified?

PDCA要約

P: A 67-year-old man presented with a 3-month history of fatigue and fever.
D: This patient has a prolonged fever without focal symptoms years after a heart transplant.
C: When the diagnosis is elusive, repeating studies or using different diagnostic methods may be necessary. These approaches avoid the cognitive error of “blind obedience,” in which a negative test result inhibits further consideration of a diagnosis despite a high pretest probability of the disease.
A: Cryptococcal meningitis