Zipf law for surgical pathology

In almost every segment of life, a small number of items usually account for the bulk of the observed activities. Though there are millions of authors, a relatively small number of authors account for the bulk of the books sold (think J.K. Rowling). A small number of diseases account for the bulk of deaths (think cardiovascular disease and cancer). A few phyla account for the bulk of the diversity of animals on earth (think arthropods). A few hundred words account for the bulk of all word occurrences in literature (think in, be, a, an, the, are). This phenomenon was observed and described by George Kingsley Zipf, who devised Zipf's law as a mathematical description. Wikipedia has an excellent discussion of Zipf's law.

Zipf's law applies to the diagnoses rendered in a pathology department. I helped write an early paper wherein three years' worth of surgical pathology reports, for a a university-associated hospital, were collected and reviewed.

There were 64,921 diagnostic entries (averaging 1.6 SNOMED codes per specimen and 1.4 specimens per patient), that were accounted for by 1,998 different morphologic diagnoses. A mere 21 diagnostic entities accounted for 50% of the code occurrences. 265 entities accounted for 90% of the code occurrences, indicating that the diagnostic efforts of pathology departments are primarily devoted to a small fraction of the many thousands of described pathologic entities.

This paper, published in 1994, is available for review

-Jules J. Berman

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tags: common disease, orphan disease, orphan drugs, genetics of disease, disease genetics, rules of disease biology, rare disease, pathology, anatomic pathology, medical nomenclature