# Sniffin’ sticks smell identification test: exploring measurement properties in an adult Brazilian healthcare professionals sample

## TL;DR

This study examines how well the Sniffin’ Sticks smell test works in Brazilian healthcare professionals, finding that age, sex, and education affect odor identification.

## Contribution

The study provides new evidence on the psychometric properties and demographic influences of the SS-16 in a Brazilian sample.

## Key findings

- The SS-16 test is unidimensional and suitable for measuring smell identification in Brazilian adults.
- Age, sex, and education significantly affect identification of specific odors like coffee, rose, and cloves.
- Peppermint and cinnamon are easiest to identify, while apple and turpentine are most challenging.

## Abstract

Olfactory evaluation has gained significant attention in both neurological and otorhinolaryngological assessments, particularly following the COVID-19 pandemic where SARS-CoV-2 infection emerged as a frequent cause of chemosensory dysfunction. The Sniffin’ Sticks identification test is a widely used screening tool for olfactory function. This study aimed to investigate the psychometric properties, specifically validity evidence based on internal structure (unidimensionality) and relations to other variables (demographic effects), of the 16-item Sniffin’ Sticks odor identification test (SS-16) in a homogeneous sample of highly educated young and middle-aged Brazilian adults, while exploring item-specific demographic effects.

A prospective observational cross-sectional study was conducted on 144 highly educated adults. The SS-16 was administered using the ‘Odor-on-lines’ paradigm. Rasch analysis assessed person-item mapping and fit statistics, while multiple regression analyses determined the effects of age, sex, and education on both overall and item-specific performance.

Rasch analysis supported the unidimensionality of the SS-16. Item difficulty varied, with peppermint, cinnamon, and fish being easiest to identify, while apple, turpentine, and liquorice were the most challenging. Item-level analyses revealed specific demographic influences: older age was associated with poorer identification of coffee (β = −0.05, p = 0.021) and cloves (β = −0.123, p = 0.001); female sex was associated with significantly better identification of rose (β = 1.15, p = 0.026); and higher education level positively impacted identification of cloves and anise (β = 0.122, p = 0.011). These item-specific effects suggest potential differential age-related vulnerability for certain odorants, possible hormonal influences on floral odor detection, and educational effects potentially linked to semantic processing of complex aromas. Smell identification capacity was classified as “very low” (<P3, SS-16 score ≤10), “low” (≤P9, 11 points), “average” (P9.1–P84, 12–15 points), and “high” (>P84, 16 points).

This study provides insights into the psychometric properties of the SS-16 in a specific sample of Brazilian adults, demonstrating both general and item-specific demographic effects on olfactory performance. The identification of item-specific influences enhances understanding of the complex interplay between biological and sociocultural factors in olfaction. While the predominance of female participants and the homogeneous high educational profile limit broader generalizability, this analysis contributes preliminary reference data for this demographic and supports the potential utility of this culturally adapted SS-16 version for clinical screening in similar Brazilian settings. Future research requires more diverse samples to establish representative Brazilian norms.