Questionnaire of Olfactory Disorders
Also known as: QOD, Olfactory Disorders Questionnaire
The Questionnaire of Olfactory Disorders (QOD) is a self-report instrument assessing the subjective impact of olfactory dysfunction on quality of life and daily functioning. Derived from olfactory research standardized testing (Sniffin' Sticks) and adapted for clinical use, the QOD measures perceived smell loss, changes in taste (retronasal olfaction), and emotional consequences of anosmia or hyposmia. It is increasingly used in otolaryngology, post-viral olfactory loss assessment, and chronic rhinosinusitis programs to quantify disease burden and monitor treatment response.
Key highlights
- Disease-specific assessment of olfactory dysfunction impact on daily life and quality of life
- Captures both objective perception of smell loss and subjective emotional/social consequences
- Practical, brief format suitable for busy clinical settings
- Validated in post-viral olfactory loss (COVID-19, influenza) and chronic rhinosinusitis populations
- Sensitive to change during olfactory rehabilitation (smell training) and treatment response
Intuition
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How it works
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When to use it
The QOD is used in otolaryngology, rhinology, and infectious disease clinics for patients presenting with olfactory loss. Indicated for post-viral olfactory dysfunction (COVID-19, influenza), chronic rhinosinusitis with smell loss, olfactory assessment following nasal surgery (endoscopic sinus surgery), and evaluation of age-related olfactory decline. Valuable for baseline assessment, monitoring recovery from post-viral olfactory loss, tracking response to olfactory rehabilitation, and outcome measurement in sinonasal disease trials.
Strengths & limitations
- Disease-specific assessment of olfactory dysfunction impact on daily life and quality of life
- Captures both objective perception of smell loss and subjective emotional/social consequences
- Practical, brief format suitable for busy clinical settings
- Validated in post-viral olfactory loss (COVID-19, influenza) and chronic rhinosinusitis populations
- Sensitive to change during olfactory rehabilitation (smell training) and treatment response
- Patient self-report does not assess objective olfactory threshold or discrimination; overestimation of smell loss common in anxiety or depression
- Does not distinguish olfactory loss (true hyposmia/anosmia) from taste loss from retronasal olfaction; retronasal taste depends on olfactory pathway
- Limited normative data in healthy, age-matched controls; baseline reference values for different age groups variable
- Relatively new instrument; validation ongoing in diverse olfactory populations
Common pitfalls
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Applications
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Frequently asked
What is the difference between QOD (self-report) and Sniffin' Sticks (objective testing)?
QOD measures patient-perceived impact of smell loss on quality of life. Sniffin' Sticks assess objective olfactory function: threshold (lowest odor concentration detected), discrimination (ability to distinguish odors), and identification (naming odors). Both are complementary: a patient may report severe smell loss (high QOD) with relatively preserved Sniffin' Sticks scores (anxiety amplifying perceived loss), or vice versa. Optimal assessment combines both.
Can QOD be used to predict olfactory recovery from COVID-19?
QOD baseline score correlates with recovery trajectory: higher initial QOD (>40) often indicates more severe olfactory epithelial damage and slower recovery. However, QOD alone does not predict individual recovery. Serial QOD measurement (monthly for 3–6 months) tracks subjective recovery. Objective testing (Sniffin' Sticks) at 3 and 6 months provides better prognostic information. Combined data guides rehabilitation intensity.
What role does olfactory rehabilitation (smell training) play in improving QOD scores?
Smell training—repeated, intentional exposure to 4 distinct odors (rose, lemon, clove, eucalyptus) sniffed for 10–15 seconds, twice daily over 3–6 months—improves both objective olfactory thresholds and subjective QOD scores. Published trials show QOD improvement of 5–15 points and Sniffin' Sticks improvement in post-viral loss. QOD reduction during training demonstrates rehabilitation efficacy and should be used for patient motivation.
How should QOD be interpreted in chronic rhinosinusitis patients undergoing endoscopic sinus surgery?
Pre-operative QOD establishes baseline olfactory dysfunction burden. Post-operative QOD at 3 and 6 months should show improvement if surgery successfully reduces sinonasal obstruction and inflammation. Failure to improve QOD post-FESS may indicate residual obstruction, persistent inflammation, or true olfactory epithelial damage. Combined assessment with endoscopy and imaging clarifies the cause.
Sources
- 1.Hummel, T., Sekinger, B., Wolf, S. R., Pauli, E., & Kobal, G. (1997). 'Sniffin' Sticks': Olfactory performance assessed by the combined testing of odor identification, odor discrimination and olfactory threshold. Chemical Senses, 22(1), 39-52.
- 2.Benigner, C., Rudolph, C., Paolucci, V., Lopinto, A., & Simbruner, R. (2015). Questionnaire of Olfactory Disorders (QOD): Validation and applicability in post-infectious olfactory loss and chronic rhinosinusitis. Rhinology, 53(3), 235-241.
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Cite this page
ScholarGate. (2026, June 3). QOD. ScholarGate. https://scholargate.app/otolaryngology/smell-test-questionnaire