Assessment of anosmia after traumatic brain injury: performance characteristics of the University of Pennsylvania Smell Identification Test.

OBJECTIVE: To examine the performance characteristics of two forms of the University of Pennsylvania Smell Identification Test (UPSIT) in a sample of persons with traumatic brain injury (TBI).
DESIGN: Analysis of consecutive admissions into a brain injury rehabilitation program.
SETTING: Midwestern medical center. PARTICIPANTS: One hundred twenty-two adults diagnosed with TBI (49% severe TBI, 16% moderate TBI, 35% mild TBI). MAIN OUTCOME MEASURES: University of Pennsylvania Smell Identification Test (UPSIT; 3- and 40-item versions).
RESULTS: Fifty-six percent of sample exhibited impaired olfaction on the full UPSIT; 40% of these patients were unaware of their deficits. Contrary to expectation, TBI patients detected dangerous odors (natural gas, gasoline, smoke) with high accuracy. Usefulness of a 3-item screening measure was examined: Missing even one item related to a 2:1 likelihood of being anosmic.
CONCLUSIONS: These findings support past investigations indicating that anosmia, and unawareness of olfactory dysfunction, are common in persons with TBI and related to injury severity. The use of the 3-item screening measure as a gross indicator was supported, although caution is advised, because nearly 20% of patients performing perfectly on the 3-item screen scored in the anosmic range on the full UPSIT.