Rise in CJD is not a true increase

BMJ 1996; 313 doi: (Published 17 August 1996) Cite this as: BMJ 1996;313:383

The rise in the number of cases of Creutzfeldt-Jakob disease (CJD), the human form of bovine spongiform encephalopathy, is more likely to reflect increased awareness among healthcare professionals than a true rise in the number of new cases, according to Austrian researchers.

Although the incidence of CJD cases reached a peak in the United Kingdom in 1994, with 59 definite or probable deaths reported to the CJD Surveillance Unit in Edinburgh, the UK figure remained only 62% of the number of cases confirmed by postmortem examination in Austria in the same year. The number of neurologically confirmed cases in 1995 totalled 1.25 per million of the Austrian population, a figure which was considerably higher than any other European country, including the UK, according to researchers writing in the Journal of Neurology, Neurosurgery, and Psychiatry (1996;61:139-42).

“Since our figures for the first half of 1996 are comparable to those of 1995, we are confident that we are missing very few cases of CJD,” said Herbert Budka, professor of neuropathology at the University of Vienna, one of the study's authors. “However, in many other parts of Europe, including the UK, there may still be a considerable degree of underreporting.”

Between 1985 and 1994 the total number of reported UK cases more than doubled, from 28 to 59 cases, which the researchers attribute to better reporting.

However, the researchers exclude the 10 cases of a new CJD variant in people under the age of 42 (average age 27), described in March by the UK's CJD Surveillance Unit. Although two of the 79 patients diagnosed as having CJD in Austria between 1969 and 1995 were 27 and 30 years old, both had classic features of CJD. “The new CJD variant appears to be evidence of increased incidence, rather than a reporting artefact. Furthermore, it appears to be unique to Britain at this time,” Professor Budka said.

Not a single case of bovine spongiform encephalopathy has been reported in Austria, so CJD is unlikely to be linked to consumption of contaminated beef products there. Austria does have many more neurologists and a higher rate of routine necropsy than Britain.

“We autopsy 70% of suspected CJD cases, but we could still improve on this figure,” said Dr James Ironside, senior lecturer in pathology at the University of Edinburgh. “While the unit is willing to help as much as it can, and we frequently perform autopsies or examine neural tissue of suspected CJD cases, we still depend on initial notification,” he added.—ALISON BOULTON, medical journalist, London

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