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Olfactory dysfunction and all-cause mortality: a systematic review and meta-analysis
Zhuoshen Lin1,2, Wenjing Liao1,2, Meiqian Xu1,2
1The State Key Laboratory of Respiratory Disease, Department of Otolaryngology, Head and Neck Surgery, Laboratory of ENT-HNS Disease, Guangzhou Institute of Respiratory Health, First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China.
Journal of Global Health
|July 31, 2026
Summary
Olfactory dysfunction, a common issue in older adults, is linked to a higher risk of death. This meta-analysis confirms this association, highlighting the need for standardized smell tests in aging research.
Area of Science:
- Gerontology
- Epidemiology
- Neuroscience
Background:
- Olfactory dysfunction is a prevalent sensory deficit in older adults.
- It serves as an early indicator of biological aging and neurodegenerative disorders.
- Emerging evidence links olfactory impairment to increased all-cause mortality risk.
Purpose of the Study:
- To systematically synthesize the evidence on the association between olfactory dysfunction and mortality in older adults.
- To address inconsistencies in effect estimates due to methodological variations in defining and assessing olfactory dysfunction.
- To provide a quantitative synthesis of the existing epidemiological data.
Main Methods:
- Systematic literature search of PubMed and Cochrane Library for cohort studies up to July 1, 2025.
- Adherence to PRISMA guidelines for study selection and data extraction.
- Multilevel meta-analytic model with restricted maximum likelihood estimation to calculate pooled hazard ratios (HRs) and 95% confidence intervals (CIs).
Main Results:
- 14 eligible cohort studies were identified, with 12 included in the meta-analysis.
- Olfactory dysfunction was significantly associated with an increased risk of all-cause mortality (pooled HR = 1.20, 95% CI = 1.11-1.29).
- Publication bias was detected and corrected using Trim-and-Fill, resulting in an attenuated but still significant HR of 1.09 (95% CI = 1.00-1.19).
Conclusions:
- Olfactory dysfunction is associated with increased all-cause mortality risk in older adults.
- The strength of this association is influenced by methodological choices in olfactory assessment.
- Standardized olfactory assessment is crucial for future research on aging populations and clinical translation.
