LOUIS, PIERRE CHARLES ALEXANDRE

Pierre Charles Alexandre Louis (1787–1872) was a French physician who graduated from the Sorbonne in 1813. He spent several years in Russia, and when he returned to Paris, he worked at l'Hôpital Charité, where he began to collect and numerically analyze information about patients and the treatments they received. His numerical method was quite new to medical practice—no one had ever before counted cases, examined the pathological lesions they had, and classified the outcome of the treatments in such detail. Louis published the results of his studies in a series of monographs, beginning with the one that made him famous, Récherches Anatomico-Pathologiques sur la Phthisie (1825). (The first English translation, Researches in Phthisis—Anatomical, Pathological, Therapeutical, was published by the Sydenham Society of London in 1844.) This is a statistical study of 1,960 clinical cases and 358 autopsy dissections of tuberculosis, and it established his reputation as a distinguished medical scientist. It is now regarded as one of the classic works of medicine.

Louis's statistical analysis of a series of cases of typhoid included evidence enabling him to distinguish it from typhus, and in fact he gave typhoid its name. In 1835, he wrote a scathing polemic on the outcome of bloodletting as a way to treat diseases (Récherches sur les Effets de la Saignée ), which conclusively proved that far from benefitting patients, this widely used and fashionable procedure harmed, and sometimes even killed them. Aspiring medical scientists who were skeptical about prevailing standards of care and had an interest in Louis's numerical approach, from other countries as well as France, sought him out as a mentor. Among his pupils were William Farr, Oliver Wendell Holmes, and Lemuel Shattuck. Louis founded the Medecine d'Observation in Paris, and he is recognized as the founding father of modern medical statistics.

John M. Last

(see also: Statistics for Public Health )

Pierre Charles Alexandre Louis

1787-1872

French Physician and Statistician

Pierre Charles Alexandre Louis is best known for an approach to medicine known as the "numerical system." Louis's admirers credited him with establishing medicine as an exact science by demonstrating the value of the statistical method in diagnostics and therapeutics. Louis's meticulous work on tuberculosis and typhoid fever provided statistical studies of the major symptoms of the diseases and the postmortem lesions associated with them. By systematically testing the effectiveness of therapeutic phlebotomy, Louis demonstrated that the timing and quantity of bloodletting had no impact on the course or mortality of the diseases for which it was commonly employed.

The son of a vineyard keeper, Louis grew up in the Champagne region of France. After a few years of law school, he became interested in medicine and studied at Rheims and Paris. He was awarded the M.D. from Paris in 1813 and joined an official mission to Russia where he worked as an itinerant doctor before establishing a medical practice in Odessa. He returned to Paris for further training after finding himself helpless during a diphtheria epidemic and began his systematic analysis of clinical findings in the wards of the Charité, one of the major hospitals of Paris.

Most of Louis's professional life was spent in Paris at La Pitié Hospital. He was greatly respected and influential as a clinician and a teacher, but he never became a member of the Paris Faculty. He was especially popular with American students who regarded him with reverence bordering on idolatry, according to Oliver Wendell Holmes (1809-1894).

Like other members of the Paris clinical school of thought, Louis was opposed to all systematic ideas and medical practices based only on theories. His disdain of theory was so great that he has been called a "radical empiricist." Louis sought truth through observation, experiment, pathological anatomy, empiricism, and statistical methods.

In Anatomical-Pathological Researches on Phthisis (1825) Louis summarized his observations on phthisis (pulmonary tuberculosis). In addition to his analysis of 358 dissections and almost 2000 clinical cases, Louis discussed epidemiological and public health issues. His observations led him to formulate "Louis's Law," which asserts that tuberculosis usually originates in the left lung and that primary lesions in the lungs precede tuberculous lesions found elsewhere in the body.

Like most nineteenth-century families, Louis's was directly affected by tuberculosis. His only son died of the disease in 1828. Once again Louis left Paris, this time on an expedition to Gibraltar to investigate yellow fever. In 1839 he published his Anatomical, Pathological and Therapeutic Researches on the Yellow Fever of Gibraltar of 1828. In 1829 Louis returned to Paris and resumed his statistical analysis of his clinical observations.

Louis's landmark work Researches on the Effect of Bleeding in Various Inflammatory Diseases, and on the Action of Emetics and Cupping in Pneumonia was published in France in 1835, and in an English translation in 1836. Louis was a member of a generation of French doctors who had become skeptical about the efficacy of traditional drugs and therapies. Most of the doctors of the Paris Clinical School turned their attention to diagnosis, arrived at by a combination of physical examination and autopsy. Louis encouraged the advocates of "therapeutic skepticism" with his demonstration that bloodletting had little or no beneficial effect on various conditions.

Typhoid fever, one of the most important disease problems and diagnostic puzzles of the early nineteenth century, was characterized in Louis's landmark treatise on the anatomy, pathology, and therapeutics of the disease. Researches Anatomical, Pathological and Therapeutic on the Disease Known under the Names Gastro-Enteric, Putrid Fever, Adynamic, Ataxic or Typhoid Fever (1829) presented the classic pathological description of the disease. The book established typhoid fever as a specific disease identified at autopsy by characteristic lesions of the spleen and mesenteric glands, and Peyer's patches. Louis was the first to describe the characteristic lenticular rose spots. The question of whether typhoid fever was different from typhus was later answered by one of his many devoted American students, W. W. Gerhard.

LOIS N. MAGNER

Pierre Charles Alexandre Louis

The French physician Pierre Charles Alexandre Louis (1787-1872) was the founder of the "numerical method" in medicine—that is, medical statistics— and the champion of exact observation and conservative deduction in medical studies.

The son of a rich wine merchant, P. C. A. Louis was born in the small town of Ai (Marne). He began his studies in Reims in 1807 and received his medical degree in Paris in 1813. He spent the next 6 years practicing in Russia. He had witnessed the havoc wrought by a diphtheria epidemic in Odessa in 1820, and on his return to Paris he hoped that further study might enable him to deal with such a calamity.

In Paris Louis saw that medicine had not progressed. Medical theory was not based on reliable data; physicians relied on their memory of striking cases in the discussion of diagnosis and justified their treatment on theoretical grounds. Louis thought that medicine could become a science only if it was based on large numbers of detailed observations which lent themselves to numerical analysis. He spent the years 1820-1826 making daily observations of all patients on two wards of the Charité Hospital. He did not treat them but obtained complete family and personal histories, detailed accounts of the onset and progression of their illness, and a complete autopsy report of those who died. He relied exclusively on his own observations, including negative findings and the results of treatment. All data were carefully recorded and whenever possible presented in statistical tables, which gave the actual number of cases. This work led to several publications, including a book on consumption (1825) and a book on typhoid fever (1829), which were translated into English. His Researches on the Effects of Bloodletting (1835) demonstrated that the benefits claimed for this popular mode of treatment were unsubstantiated.

Louis's influence spread through the foreign students who flocked to Paris, attracted by his approach. His American students propagated Louis's numerical method in the United States, where the emphasis on the collection of observable, detailed data and their statistical analysis was readily appreciated and became a guideline for medical research.

Although Louis's work had been largely responsible for overthrowing the old theory, recognition of his importance in Paris was not unanimous. He was not elected to the faculty. He continued his teaching at the hospitals and became a member of the Academy of Medicine and, in 1832, president of the Society for Medical Observation in Paris, founded by his admirers and students. Out of a similar society founded in Boston grew the concept of the clinical-case conference.

Louis lived to see the rising importance of laboratory research for medicine. Medical science could not rest completely on the statistical analysis of bedside observations and autopsy findings, as he had proposed. But his demand for reliable quantifiable data in clinical medicine and for the statistical determination of the efficacy of treatment became one important basis of modern medicine.

Further Reading

There is little biographical material on Louis in English. Henry I. Bowditch eulogized him in Brief Memories of Louis (1872). His place in the development of medical statistics is defined in Charles Singer, A Short History of Medicine (1928; 2d ed. with E. Ashworth Underwood, 1962). An excellent description of contemporary medicine and of the context in which the work of Louis developed is in Erwin H. Ackerknecht, Medicine at the Paris Hospital, 1794-1848 (1967). □