Using Catchment Population to Estimate Sporadic Creutzfeldt-Jakob Disease Incidence

Catchment populations have several uses. A method using catchment population to estimate the incidence of sporadic Creutzfeldt-Jakob disease (sCJD) is described.

A cohort of nine consecutive patients diagnosed with sCJD, symptom onset spanning 26 months, were observed at a rural tertiary university medical center that has approximately 40,000 hospital discharges annually. An effective catchment population was determined using surrounding county utilization frequency that captured all nine sCJD patients and accounted for over 87% of discharges.

The effective sCJD hospital catchment population was 1.266 million, implying an annual sCJD incidence rate of 3.39 per million (95% CIs, 1.55-6.43), assuming a Poisson distribution for sCJD occurrence.

This annual incidence rate suggests that many sCJD patients are unrecognized and unreported. An advantage of this catchment population method is independence from death certificate accuracy, important in rare diseases that are both rapidly and invariably fatal. The relative absence of significant healthcare systems competition in this rural population enhances the reliability of this finding. The most likely explanation for the high sCJD incidence rate suggested by this study is enhanced clinical suspicion and improved diagnostic accuracy.