The development of a disease classification system, based on the International Classification of Diseases, for use by neurologists.

Effective planning and evaluation of medical services is only possible if appropriate and reliable information is available. Diagnoses of patients seen are essential data. The epidemiological value of standard, reliable diagnostic data could also be considerable. The International Classification of Diseases (ICD) is the only system currently available which provides a common basis of classification for general statistical use. A booklet, using ICD codes, for classifying in-patients and out-patients seen by neurologists has been developed. It is simple and easy to use, affords the necessary economy of time, and should result in uniformity of coding. Reliability studies confirm that inaccuracies occur when patients' diagnoses are coded retrospectively from their medical files, even when observers are medically trained. It is recommended that doctors should accept personal responsibility for coding patients' diagnoses at the time of consultation or discharge from hospital.