Validity and Reliability of Persian Smell Identification Test

Introduction: Smell Identification Tests (SIT) are routinely utilized for the clinical evaluation of olfactory function. Since Iran consists of various ethnic subgroups, the reliability and validity of this test as a national SIT are required to be evaluated across the country.   Materials and Methods: This cross-sectional study evaluated the cultural adaptation of SIT administered to 420 healthy volunteers from 6 various ethnic subgroups (i.e., Fars, Turk, Kurd, Lor, Baluch, and Arab) living in 7 cities (one city for each subgroup, and Tehran [capital of Iran] with mixed ethnicities). The SIT consists of pens pre-filled with 24 odorants. The correct identification response rate was evaluated in all and each subgroup. The test was performed twice on 60 participants with a 2-week interval to assess its reliability. The SIT was further administered to 150 cases with documented abnormal olfactory function to evaluate its validity.   Results: The correct identification response rate was estimated at 70% for all odorants in all and each subgroup. The mean odor identification score was 21.41±1.37 (score range: 17- 24) with no significant difference among various subgroups. Moreover, the test-retest correlation coefficient was obtained at 0.77. The mean odor identification score in patients with olfactory impairment was 10.69±3.76, which was significantly different from that in healthy participants (P<0.001). The best cut-point for the beginning of olfactory impairment was 17.5 (95% CI: 9-100, Sensitivity=99, Specificity=81). Females obtained higher scores of odor identification, compared to males (P=0.025).   Conclusion: The results indicated the reliability and validity of the SIT, which can be used nationally for the assessment of olfactory function in various ethnic subgroups across the country.