Severe drug-induced liver injury (DILI) remains a major safety issue due to its frequency of occurrence, idiosyncratic nature, poor prognosis, and diverse underlying mechanisms.

https://pubmed.ncbi.nlm.nih.gov/26206150/

Glaucoma following penetrating keratoplasty is one of the serious complications due to its frequency of occurrence, difficulty in diagnosis and management, risk of graft failure and irreversible visual loss due to optic nerve damage.

https://www.ijclinicaltrials.com/index.php/ijct/article/view...

Par argument de fréquence, les pneumonies lobaires bactériennes, bronchiolites infectieuses et œdèmes pulmonaires cardiogéniques sont les diagnostics différentiels le plus souvent retrouvés.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7203047/

Il faut tout d’abord localiser la lésion dans le genou, puis la rattacher à une structure anatomique ; enfin le contexte clinique, épidémiologique (âge du patient, argument de fréquence, signes associés) et la caractérisation en IRM permettent de mieux préciser le diagnostic

https://www.sciencedirect.com/science/article/abs/pii/S22115...

Despite the absence of an epithelial contingent on this biopsy material, the hypothesis to be favoured by its greater incidence is that of a caecinosarcoma ;

https://www.britannica.com/science/prevalence#:~:text=Preval...

it means that the diagnosis is made more probable ALSO based on how many people already have the disease in the current population; the positive predictive power is indeed a combination of prevalence and the statistical features of the tests/diagnostic methods (specificity and sensitivity)

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Note added at 19 hrs (2023-02-18 12:53:25 GMT)
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https://sphweb.bumc.bu.edu/otlt/MPH-Modules/EP/EP713_Screeni...

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Note added at 19 hrs (2023-02-18 12:58:47 GMT)
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Put more simply in plain English it means : because it's the most probable among the possible diagnoses given the symptoms and other clinical examinations or tests.

Sutton's law states that when diagnosing, one should first consider the obvious. It suggests that one should first conduct those tests which could confirm (or rule out) the most likely diagnosis.
https://en.wikipedia.org/wiki/Sutton's_law




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Note added at 1 day 16 hrs (2023-02-19 10:03:37 GMT)
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Or: Woodward's maxim ("When you hear hoofbeats think of horses not zebras"). Based on this saying, more exotic diagnoses are still called "zebras" in med slang.