The validity and reliability of the Italian Olfactory Identification Test (IOIT) in healthy subjects and in Parkinson's disease patients

BackgroundOlfactory function can be rapidly evaluated by means of standardized olfactory tests. Multiple-choice smell identification tests can be conditioned by cultural background. To investigate a new tool for detecting olfactory deficit in Italian subjects we developed a multiple-choice identification test prepared with odorants belonging to the Italian culture.MethodsThe Italian Olfactory Identification Test (IOIT) was developed with 33 microencapsulated odorants with intensity of odors and headspace Gas Chromatography being tested. Test-retest reliability of the IOIT was evaluated. The IOIT was administered to 511 controls and 133 Parkinson's patients.ResultsIn healthy subjects the number of IOIT errors increased with age for both females (p < 0.0001) and males (p < 0.0001), while in the Parkinson's disease group the number of IOIT errors was significantly greater where compared to healthy subjects (p < 0.0001 in all age groups). The reference limits applied to all age groups revealed an IOIT sensitivity of 93% and a specificity of 99%. The test-retest reliability was excellent.ConclusionThe IOIT is highly reliable, disposable, easy to administer, not fragile, and has a long shelf-life. All these features make the IOIT suitable for clinical use as well as for population screening and to discriminate Parkinson's patients from healthy subjects.