Comparison of diagnostic findings using different olfactory test methods.

Objective: To quantify discrepancies in the diagnosis of olfactory function that might exist when comparing results obtained from centers using different methods of olfactory testing.

Study Design: Prospective study of 50 healthy adult volunteers and 25 adult patients with olfactory complaints.

Methods: Two test methods, the Connecticut Chemosensory Clinical Research Center (CCCRC) test widely used in the United States, and the Jet Stream Olfactometer (JSO) test used in Japan, were used to measure and categorize the diagnostic level of olfactory function (normosmia, mild hyposmia, moderate hyposmia, severe hyposmia, anosmia). Olfactory function was measured separately for each nostril.

Results: There was a significant correlation (rs = 0.788, P < .01, n = 150 nostrils) between diagnostic categories assigned by the CCCRC and JSO test methods. Diagnostic categories were identical for 66.7% of the nostrils tested, and in only 7.3% of the cases did the results differ by more than one category. For the anosmic and normosmic categories, test results were in agreement 91.7% of the time, whereas for the hyposmic categories (mild, moderate, and severe) results were in agreement only 22.2% of the time.

Conclusions: Our results demonstrate that when comparing clinical or research data obtained from centers using different olfactory test methods, subjects with diagnoses of anosmia or normosmia may be more reliably compared than those with different levels of hyposmia.