Original article by Donna C. Bergen, M.D. published 29 October 2009 in World Neurology Vol 24 No. 5

Collaboration between the World Federation of Neurology and the World Health Organization has moved into the important area of disease classification.

Although systems of disease classification were begun as early as the 18th century, since its founding in 1946 the WHO has been responsible for preparing and updating the International Lists of Diseases and Causes of Death (ICD). In fact, the ICD is more than 100 years old, making it older than the WHO. One of the WHO's earliest official actions was to approve the ICD-6.

Since then, the WHO has periodically revised the ICD codes. The current ICD-10, which is being used in most countries, was approved in 1990 by the World Health Assembly, which consisted of the health ministers of the WHO member states. The codes are used as universally recognized diagnostic labels by clinicians, by epidemiologists charting disease prevalence and incidence, by researchers, and by public health officials and health care planners responsible for resource allocation and training programs. Ministries of health use the code when reporting causes of death and disease rates to the WHO, and some health systems use the disease codes in reimbursement for health care. (Some countries, notably the United States, still use the ICD-9 version.)

In June, the ICD-11 Committee was convened in Geneva by Dr Shekhar Saxena and Dr Tarun Dua of the WHO's Programme for Neurological Diseases and Neuroscience, Department of Mental Health and Substance Abuse, the WHO division that is responsible for disorders of the nervous system. The meeting was chaired by Dr Raad Shakir of Imperial College, London. Representatives from a range of international neurological organizations participated, including Alzheimer's Disease International, the International Brain Research Organization, International Child Neurology Association, World Federation of Neurosurgical Societies, International Neuropsychological Society, International League Against Epilepsy, International Headache Society, Multiple Sclerosis International Federation, World Stroke Organization, and Movement Disorder Society. Dr Johan Aarli represented the WFN. The revision will include three versions: for primary health care workers, neurology specialists, and researchers.

For the first time, the revision process will be fully transparent. A beta draft is expected in 2011, and it will be field-tested at various sites around the world for feasibility, reliability, clinical utility, and validity. Committee members will be seeking and choosing these sites over the next half year. The penultimate draft will be posted on the WHO Web site, and interested parties and the public will be invited to respond. It is hoped that the final version will be submitted to the World Health Assembly in 2014.

Advances in neurogenetics, molecular biology, neuroimmunology, and other fields have prompted dramatic changes in disease classifications. Categories of disorders once classified by clinical phenotype, for example, have been reshuffled to reflect their specific genetic causes, new disorders have been discovered, and some diagnostic categories have been redefined to reflect new understanding of their causes and risk factors. Many hope computerized health data management will facilitate more frequent remodelling of the ICD-11 codes to keep up with the growth of neuroscientific and clinical knowledge. The absolute need to track epidemiological disease data over time requires each modification of the ICD to be "mappable" onto the previous version, a function simple for computers but highly complex for those devising each new classification. (See www.who.int/classifications/icd.) ■


At time of print, Donna C. Bergen, M.D. was Chair of the WFN Public Relations and WHO Liaison Committee