Reliability of death certificate data on vascular lesions affecting the central nervous system.

Although it is generally stated that national mortality statistics are to some extent unreliable, it is difficult to ascertain their degree of unreliability. In studies carried out in limited areas of Czechoslovakia, Japan and Sweden it has been possible to determine the cause of death at autopsy in a large series of cases, and the findings relevant to "vascular lesions affecting the central nervous system" (CNS) have been compared with the national mortality statistics for the same causes and with the clinical findings.It was found that death rates for vascular lesions affecting the CNS, taken as a whole, obtained from the autopsy studies were close to the national figures but that the ratio of cerebral haemorrhage to cerebral infarction was lower in the autopsy data, indicating that classification into cerebral haemorrhage and cerebral thrombosis is incorrect in the national figures and that the former is over-diagnosed at the expense of cerebral thrombosis.Comparison of the autopsy data with clinical diagnoses in Prague and Malmö showed that only 70% of the cases of fresh cerebral vascular accidents regarded as the principal cause of death by the pathologist were diagnosed before autopsy, and that many cases found by the pathologist but not considered to be the principal cause of death were not suspected clinically. Less than 1% of cases of cerebrovascular accident regarded as the principal cause of death by the clinician were not found by the pathologist.