Volume 8: Variant CJD
4. Work of the CJD Surveillance Unit
Retrospective study of CJD

4.2 Although there had been epidemiological studies of CJD carried out between 1970 and 1984 in both England and Wales, these studies had not been extended beyond 1984. The CJDSU's first task was therefore to fill this gap in epidemiological data and include data from Northern Ireland and Scotland.

4.3 Information for the retrospective analysis came from death certificates provided by the Office of Population Censuses and Surveys (OPCS) and equivalent bodies in Northern Ireland and Scotland. Direct referral of cases from neuropathologists, neurologists and electrophysiologists was also encouraged. A total of 260 suspect cases of CJD were ascertained in this study. ¹ Hospital records were obtained for all these cases, but no questionnaires were used. These suspect cases were then classified using criteria based on those established by Masters et al. in 1979 ² (see paragraph 3.12 for a description of the criteria).

4.4 The overall incidence over the period studied, 1985 to 1990, was 0.46 per million per annum, which was consistent with the 1980-84 survey of CJD in the UK.

4.5 The clinical features of CJD in this survey were also analysed. This was an important aspect of the survey as it was believed that if BSE was transmitted to humans it might present itself in a different manner to that previously seen in CJD. The frequency of clinical features such as myoclonus (muscle spasms), pyramidal signs (abnormal reflexes) and akinetic mutism (impairment of voluntary movement) were comparable to the previous investigations.