The report by Bongianni et al1 in this issue of JAMA Neurology compares the results of cerebrospinal fluid (CSF) and nasal brushings as samples for the detection of misfolded prion protein using the latest refinement of the real-time quaking-induced conversion (RT-QuIC) test. Two earlier studies2,3 reported test results of CSF and nasal brushings using a less refined RT-QuIC method on groups of patients with sporadic Creutzfeldt-Jakob disease (CJD) and patients with non-CJD neurologic and nonneurologic diseases. Taking into account some patient overlap, the total number of individuals undergoing testing from all 3 studies now includes 61 patients with sporadic CJD, 98 patients with other neurologic diseases, and 23 patients with nonneurologic diseases. The test has almost perfectly distinguished patients with sporadic CJD from the control groups, with a combined 97% sensitivity and 100% specificity (100% sensitivity and specificity for patients in the present study).
Brown P. A New Standard for the Laboratory Diagnosis of Sporadic Creutzfeldt-Jakob Disease. JAMA Neurol. 2017;74(2):144-145. doi:10.1001/jamaneurol.2016.4877