Reliability and validity of the classification of death in general practice.

The general practitioner in the Netherlands is solely responsible for assigning the natural causes of a patient's death when it occurs at home and for entering it on the certificate of death B, which is then forwarded to the CSO (Central Statistics Office). The CSO however, records the cause of death in the appropriate category of the ICD-9 of the WHO. The value of these data, therefore, depends upon the agreement between the general practitioner's cause of death and the CSO categories of causes of death. To assess the degree to which the CSO classification reflects the general practitioner's cause of death, form B from eight general practitioners practicing in Hoorn were compared with the classification of the CSO during a period of five years, 1979-83. There was a 65% (237/365) agreement between the classifications. Of the remaining 128 cases 68% (87/128) of the classification differences were caused by a wrongly described cause of death on the B certificate. In 32% (41/128) the classification rules of WHO made it hardly possible for the general practitioner to classify uncertain causes of death. The conclusions of this survey are that the quality of the statistics on causes of death will improve if the general practitioners are more careful with filling in the certificate of death B; the classification rules of the ICD-9 makes it possible to classify unknown causes of death; and if the certificate of death B becomes more 'user friendly'.