経験頻度、主観確率

最近、実感するのは、英語が日本語に比べ、総論と各論を明確に区別する言語であるということ。それが、冠詞や数に反映されているのではなかろうか。しかし、臨床的な推論において、一般論は、個人的な経験の回数などたかが知れているので、「３の法則」持ち出すまでもなく、"Always"や"Never"の極論の主張は限定的なものとなり、蓋然性を伴うものになる。

Always(33) 100%

• Endocarditis is always a concern in an elderly patient with a prolonged, nonlocalizing fever. "Ring around the Diagnosis"

Usually(145) 90% / Generally(69) 75%

• Erythema nodosum is usually a clinical diagnosis and does not generally require biopsy unless atypical features are present. "Footprints"

Often(198) / Frequently(64) 60%

• The serum phosphate level is often low in primary hyperparathyroidism, but the presence of renal failure in this patient clearly limits its usefulness. "Stopping Short of Certainty"
• Trichinosis frequently produces subclinical infections, but late presentations often include muscle aches, cardiac symptoms, and eye disturbances that are absent in this patient. "Where Are You From?"

Sometimes(41) 50%

• An atrial myxoma can sometimes cause episodic dyspnea, but usually not chest pain. "Rare × Rare"

Occasionally(28) 40%

• Back pain is occasionally the presenting symptom of endocarditis, although it is not usually associated with radiographic abnormalities. "Where Did Good Old Clinical Diagnosis Go?"

Rarely(39) 20%

• Bacterial infections are rarely a cause of chronic diarrhea. "Needle in a Haystack"

Hardly ever(0) 10%

Never(11) 0%

• Treatment with cephalosporins often results in a positive Coombs' test but almost never causes hemolysis. "Chest Pain with a Surprising Course"

参考

• オッズの非数値表現
• 医療における頻度を表す言葉と確率の接点