Validity and Reliability Testing of the National Health and Nutrition Examination Survey (NHANES) Taste and Smell Protocol

The NHANES 2011–2014 protocol includes a taste and smell questionnaire (CSQ) in the home interview followed by brief olfactory and taste assessment in mobile exam centers. The CSQ asks self-reported taste and smell ability, and selected symptoms, comorbidities, and treatment for chemosensory disorders. In the taste assessment, participants rate intensities of 1 M NaCl and 1mM quinine hydrochloride applied to the tongue tip and these plus 0.32M NaCl sampled with the whole mouth. Smell function is assessed with two 4-item, scratch-and-sniff tests (Pocket TestsTM (PT), Sensonics, Inc.) to classify normosmia and olfactory dysfunction from microsmia to anosmia. We examined the NHANES protocol test-retest reliability and compared the PT to an Olfactometer identification task. Seventy-seven adults (mean age=39, range: 18-87 years) were tested at baseline and 2.5 weeks. Taste intraclass correlations (one-way random, single measures) ranged from 0.47-0.71 (moderate to substantial agreement). Classification of olfactory function agreed for 97% of participants across two PT trials (κ =0.65). Compared to the Olfactometer at each testing session, the PT averaged 50% sensitivity (true positive rate) and 100% specificity (true negative rate) to identify olfactory dysfunction. All adults incorrectly classified by PT were mild microsmics. If detecting moderate to severe dysfunction, the PT averaged 100% sensitivity and 97% specificity. A subsample (50 adults) completed testing at 6.5 months to test the CSQ stability. The six CSQ items pertaining to chemosensory impairment had moderate to near perfect agreement (ICC single measures, 0.57-0.94). These findings indicate that the NHANES chemosensory protocol has good test-retest reliability and is highly sensitive in identifying moderate to severe olfactory dysfunction.