Low specificity and sensitivity of smell identification testing for the diagnosis of Parkinson's disease

The aim of this study is to determine if the University of Pennsylvania's Smell Identification Test (UPSIT) is an accurate diagnostic tool for olfactory dysfunction in Parkinson's disease (PD).

We included 138 non-demented PD subjects and 175 control subjects matched by gender. Smell identification was tested using UPSIT.

The mean number of UPSIT items correctly identified by controls was 27.52 ± 5.88; the mean score for PD subjects was 19.66 ± 6.08 (p=<0.001). UPSIT sensitivity was 79.7% with a specificity of 68.5% using a cut-off score of ≤ 25. The overall accuracy for the diagnosis of PD was of 75.3%.

UPSIT accuracy and specificity were lower than what has been previously reported. Our data demonstrates that 17.5% of items of the UPSIT were not well identified by healthy controls. Further research of the identification of a truly cross-cultural test is warranted.