Evaluation of the Australian CJD surveillance system.

An evaluation of the surveillance capacity of the Australian National Creutzfeldt-Jakob Disease Registry (ANCJDR) was undertaken. It focused on the ability of the Registry to detect CJD in Australia and, in particular, to identify cases that require public health responses. The Registry relies on a complex reporting system and staff with expertise to accurately identify and classify cases of CJD. The Registry satisfies the criteria of flexibility and acceptability and has a high positive predictive value and representativeness. The sensitivity of the system could not be evaluated, as the rarity of the condition precludes an independent assessment of the incidence of CJD, but the incidence of CJD is comparable to that found in other countries. The time required to establish a definite diagnosis of CJD is approximately 2 months, impacting negatively on the timeliness of the system. In order to maximise the likelihood of detecting all cases of CJD in Australia in a timely fashion, suggestions are made for improving the system's sensitivity and timeliness of reporting as well as for using methods that allow meaningful comparisons of incidence between populations with different age structures.