Test-retest reliability of the San Diego odor identification test and comparison with the brief smell identification test

This study described the San Diego Odor Identification Test (SDOIT) reliability and compared the SDOIT and the Brief Smell Identification Test (B-SIT). Ninety participants aged 50-70 years completed this 2-visit olfaction study. During visit 1, the SDOIT and B-SIT were administered according to standard protocols. Three weeks later, participants returned to retake the SDOIT. The SDOIT score was the total number of odorants correctly identified out of 8 odorants presented, and olfactory impairment was defined as correctly identifying less than 6 odorants. The B-SIT score was the total number of odorants correctly identified out of 12 odorants presented, and participants correctly identifying less than 9 odorants were categorized as abnormal. The SDOIT reliability was high (concordance correlation coefficient = 0.85, 95% confidence interval [CI] = 0.79-0.91). The same score was obtained on retest for 73% of participants, whereas 18% improved, and 9% declined. Test-retest agreement was 96% for the SDOIT; 4% improved from impaired at visit 1 to unimpaired at visit 2. Overall, SDOIT impairment classification and B-SIT abnormal classification agreed in 96% of participants (κ = 0.81, 95% CI = 0.63-0.99). In conclusion, the SDOIT showed good test-retest reliability. Agreement for impaired/ abnormal olfaction was demonstrated for the SDOIT and the B-SIT.