Medical Coding in the United States: Introduction and Historical Overview

Abstract

The Merriam-Webster definition of “code” includes the concepts of a system of principles or rules, a system of letter and number symbols used to represent assigned meanings, and a set of instructions for a computer [1]. Medical diagnostic and procedural coding as we know it today incorporates all of these concepts and has diverse applications including vital statistics tracking, hospital medical record indexing, clinical research abstraction, health care delivery analytics, and medical service reimbursement. The origins of modern medical coding, however, lie in medieval epidemiology. Europe was being ravaged by recurring epidemics of bubonic plague, and efforts at infection control included determining when deaths were due to plague or to other causes. In early sixteenth century London, the causes of death were assigned by “searchers” who viewed the bodies and reported their findings as either plague or other; physicians were consulted only when searchers were uncertain. In Northern Italy, boards of health undertook similar initiatives but required that final diagnoses be certified by a physician or surgeon [2]. Although the plague subsided, interest in the population health data stored in death registries grew as the Industrial Age unfolded. The need for standardized language and systematic classification of the data became apparent, leading to products such as the Nomenclature of Diseases Presented by the Royal College of Physicians, first published in 1869. The Royal College of Surgeons also contributed to this work. Multinational efforts undertaken under the auspices of the International Statistical Institute resulted in the release of the International List of Causes of Death in 1893, which recently had become known as “ICD.” Supplements to its first revision (“ICD-1”) included guidelines for data entry clerks and an alphabetized index with mapping to the tabular main list; these features continue in ICD as we know it today [2].