Richard EarlamRichard Earlam

Disease Names

NUMBERS AND WORDS

About 40 years ago my first epidemiological article appeared in 1969 from the Mayo Clinic showing that achalasia had an incidence of about 1:100,000 (PDF 12Download file). In spite of the clinic having the largest series of achalasia in the world it was difficult to obtain all the cases in the surrounding district because of vague words used in the diagnosis. Another article was written emphasizing words and numbers but in relationship to junior surgical training posts, their names and the length of time spent in training to become an independent consultant based on a comparison with the atomic nucleus and physics (PDF120 Download file).

The last article on the subject appeared in 2007 (PDF 146Download file) but this time words and their true arithmetic equivalent meaning, assessed by measuring probabilties in actual percentage figures, used in obtaining consent for an operation was the main interest.

PROFESSOR J G SCADDING

In by 1988 I discovered a wise man from the past who was interested in how doctors used words for diagnosis and what the true endpoint was in each and every usage. This was Professor John Guyett Scadding (1907-99), respiratory physician from the Brompton Hospital. His best quotes are;
“At whatever point the diagnostic process comes to a halt, its end-result is expressed in terms of disease”.
“The concept of a disease is thus an abstraction from the reality of phenomena observed in patients, useful because it permits of thinking, speaking and writing in generalisations”.
Scadding was interested in the medical classification of diseases and, in retrospect, unluckily, used the original Greek word nosology which had the unfortunate result hiding the true value of his work.

The American pathologists had developed the Systematised Nomenclature of Pathology SNOP based on the two axes of Topography or Anatomy and Morphology or Pathology. Its limitations were recognised and they developed the Systematised Nomenclature of Disease (SNOMED) in 1979 which added four more axes to make six, namely Aetiology, Function or Symptoms, Procedure and Disease. There are now 11 (is it becoming too large ?). Scadding demonstrated this methodology for respiratory disease, with examples:

  1. bronchial carcinoma – topography and morphology
  2. pulmonary tuberculosis – topography, morphology and aetiology
  3. bronchia asthma – disease, symptoms F, topography, morphology and aetiology.

This basically presented the same problem which gastroenterologists have with the “old” end points of hiatus hernia, peptic ulcer and gallbladder disease. With the research that led to the confirmation that the epigastric pain of duodenal ulceration arose from the lower oesophagus and not the stomach or duodenum, it was clear that the end point of a duodenal ulcer diagnosis was false. This was discussed in the last section and it is the reason why the author became interested in the nomenclature of diseases and SNOMED. In the UK this has now been institutionalised as SNOMED CT. Luckily it is compatible with the older International Classification of Diseases (ICD).

SNOMED

This diagram represents SNOMED, which is a multiaxial hierarchial and computerised system of nomenclature. It acts as a background to the following research done over the last forty years.

SYSTEMATISED NOMENCLATURE OF MEDICINE

img002

EPIDEMIOLOGY

For most diseases it is helpful to have some idea about the epidemiology of its incidence and prevalence. Not only does this help in diagnosis because “commonest things are common” but it assists the analysis of treatment. Achalasia is rare (PDF 12Download file) and because it does not shorten life whether treated or not its prevalence can be calculated once the age of presentation is known. A study of the workload of a general surgeon in 1983 demonstrated that many of the common cancers were treated by them so it would be valuable to have their incidence (PDF 74Download file, 80Download file). These were examples of commoner diseases than achalasia. A study on the incidence and survival of breast cancer patients indicated that one third did not die because of their disease but died a natural death unrelated to it (PDF 112Download file), thus providing some optimism. A study of pancreatic cancer in England and Wales confirmed that two-thirds did not undergo a surgical operation and about half were over the age of 70 at presentation (PDF 84Download file). Survival was less than 3% at five years. This was the numerical part of the analysis but the use of words, disease and nomenclature was important because there is a subset of pancreatic cancer called carcinoma of the Ampulla of Vater which is much more benign its natural history. It was these patients who provided most of the five year survivors. Information from epidemiology is essential for decisions about screening for pancreatic cancer (PDF 86Download file).

Further studies were done on the numerical analysis of survival in oesophageal cancer in England and Wales based on mortality figures (PDF 72Download file). This showed that the crude death rates per 100,000 were 8.7 for males and 6.4 for females and that the figures had increased by about one-third in 1982 over the previous 10 years. It was clear that the data was incomplete both in regard to anatomical and histological axes, contained no separation between squamous-cell and adenocarcinoma, no staging, nor whether operative surgery or other treatments had been used.

Later studies on oesophageal cancer were improved by analysing the literature in regard to histology, staging and treatment (PDF 62Download file). But in the absence of histology, information about investigations and pre-treatment staging, no useful epidemiology of the incidence of oesophageal cancer can yet be made.

TNM CLASSIFICATION OF CANCER AND SNOP

The staging of cancer is based on the assessment of the TUMOUR T, the loco-regional lymph NODES N and distant METASTASES M. With different combinations of TNM, staging can and must be performed for each and every patient in any treatment or epidemiological paper. Without this data proper comparisons can not be made unless it is apparent that similar groups of patients are equal. For instance this also applies in breast cancer screening by mammography when comparing Sweden with the UK. In a study of breast cancer data collection we confirmed that the five year survival rate for breast cancer is 80% for Stage I, 60% for Stage II, 40% for Stage III and 20% for Stage IV (PDF 112Download file). Data from the Hospital Activity Analysis HAA for operations was useless; for instance a code could be chosen for “mastectomy not elsewhere classified (NEC)” so 20% were thus coded. The TNM classification via SNOP has now been included in SNOMED under the T and M axes.

SURGICAL OPERATION CLASSIFICATION

This can either be done by choosing the most common operations provided by the HAA as a 10% sample taken by the Hospital Inpatient Enquiry (HIPE) or choosing from the Procedure P axis from SNOMED. The latter includes 0 = incision, 1 = excision, 2 = injection, implantation, 3 = endoscopy, 4 = repair, transplant, 5 = destruction, 6 = closure, 7 & 8 = manipulation(PDF 96Download file).

In two editions of a book entitled Concise Korner Coding Book 1st Ed 1988, 2nd Ed 1991, the author combined for each chosen surgical region in general surgery the ICD-9 four figure code for disease with the Office Public Census Survey OPCS operation code (103,113). Surgical operations were very carefully chosen as those being present in the accepted major textbooks of surgery indexes and then given a suitable code chosen from the usual nonsensical list, eliminating those that I as a surgeon could not even understand. It was thus a simplified CODING system for disease and operation. The pigeon holes had been chosen. Every operation had to have a name and number and every surgical operation had to have been performed for some defined reason, which did actually include vomiting or abdominal pain (vague or not elsewhere classified).

This was the unsatisfactory state that existed with the ICD coding system for diseases and the nonsensical list of possible operations provided by the government. Garbage in, garbage out. No simplification by practising surgeons was allowed to help the poor coding clerks in their complicated work. The problem was clearly defined in my article in the British Medical Journal in 1988 (PDF 96Download file).

NOMENCLATURE SNOMED IS DIFFERENT FROM CODING (ICD)

The original International Classification of Disease ICD was a single axis system limited because each concept has to be coded with a single number.

A multiaxial system like that used on the old UK car registration mixed three letters (1-26) with three numbers 1-999 but soon ran out of space. So use of towns identified by two letters, followed by two digits for the year of registration and than three letters gives more choices. It demonstrates that multiaxial alpha-numeric combinations can provide more spaces. But the hierarchical concept is even cleverer because each subdivision of 0-9 can add more specificity than any bi-axial system such as homo sapiens and his best friend canis domesticus. The additional advantage of a hierarchial system is that it can move downwards with more figures to a specific individual nomenclature or upwards to larger groups with less subdivision. This can not be provided by coding alone. But it has its origins in simple coding of single axis or bi-axial type.

Coding is not capable of development into the addition of new diseases or symptom complexes. SNOMED is capable of allowing new diseases due to aetiology or agreed collection of symptom complexes to devolve.

Screen Shot 2015-03-10 at 15.58.53

Coding is not capable of development into the addition of new diseases or symptom complexes. SNOMED is capable of allowing new diseases due to aetiology or agreed collection of symptom complexes to devolve.

An example of this comes from the Montreal Definition and Classification of Gastroesophageal Reflux disease: a global evidence-based consensus. Vikil N et al American J Gastroenterology 101:1900-20 (2006). The full article is available through Google Scholar. In 50 agreed statements they move to the establishment of a new disease based on the end points of symptoms rather than pathology. In their 205 references of an extremely well documented work they do not mention Professor J G Scadding nor SNOMED. They do not analyse how clinicians use the word disease. However they do correctly and in scientific detail describe a symptom complex that perfectly fits in with SNOMED’s D axis of a DISEASE COMPLEX. This is a great advance but it would have helped to explain the intellectual process of the new ideas versus the old.

REFERENCES

12. Achalasia of the esophagus in a small urban community (PDFDownload file)
Earlam R J, Ellis F H Jr, Nobrega F T
Mayo Clin Proc 44:478-83 (1969) PMID 5788257

62. Oesophageal squamous cell carcinoma : I A critical review of surgery. (PDFDownload file)
Earlam R J, Cunha-Melo J R
Brit. J. Surg 67:381-90 (1980) PMID 6155968

72. The epidemiology of oesophageal cancer with special reference to England and Wales.(PDFDownload file)
Earlam R J, Cunha-Melo J R, Donnan S P, Evans S J
Ital J Gastroenterol 14:244-9 (1982)

74. General surgical workload in England and Wales.(PDFDownload file)
Allen-Mersh T G, Earlam R J
Brit Med J 287:1115-8 (1983) PMID 6414594

80. Oesophageal cancer treatment in North East Thames region, 1981: medical audit using Hospital Activity Analysis data.(PDFDownload file)
Earlam R J
Brit Med. J. 288:1892-4 (1984) PMID 6203599

84. Pancreatic cancer in England and Wales: surgeons look at epidemiology.(PDFDownload file)
Allen-Mersh T G, Earlam R J
Ann Roy Coll Surg Eng 68: 154-8 (1986) PMID 3729266

86. Early diagnosis and screening for pancreatic cancer.(PDFDownload file)
Lancet 785-6 (1986) Editorial

96. Korner, nomenclature, and SNOMED. (PDFDownload file)
Earlam R J
Brit Med J 296:903-5 (1988) PMID 3129068

103. Concise Korner Coding Book for General Surgery and Urology
(1st Edition). Glaxo, April (1988) Book

112. Breast cancer data collection for surgical audit.(PDFDownload file)
Woods W G, Earlam R J
Ann Roy Coll Surg Eng (Eng.). 73: 364-72 (1991) PMID 1759766

113. The Concise Korner Coding Book for General Surgery and Urology
Earlam R J
2nd Edition. Chapman and Hall, London (1991) Book

120. Heisenberg’s uncertainty principle and the surgical registrar problem.(PDFDownload file)
Earlam R J
Theoretical Surgery 8:38-43 (1992)

146. Obtaining consent for an operation: a choice of words or numerical probabilities? (PDFDownload file)
Earlam R J, Rizwan-Hasib M, Tross S Z, Morris G
Clinical Risk 13:45-52 (2007)

info@richardearlam.com | Richard Earlam. All Rights reserved

Jigsaw Design Studio | Website Designer