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

OBJECTIVE: 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).

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

RESULTS: 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%.

CONCLUSION: 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.