Epidemiology of olfactory dysfunction in China: a nationwide population-based cross-sectional study

Background Olfactory dysfunction is associated with adverse health outcomes such as neurodegenerative diseases. However, few large-scale epidemiological studies in China have focused on olfactory function using psychophysical testing. This study seeks to investigate the prevalence of olfactory dysfunction among healthy adults through a large-scale, nationwide survey and to examine its associations with demographic and other factors.Methods The study was conducted across multiple locations in China between 2023 and 2024, involving local residents aged 20 and above. A total of 12,153 participants underwent the T&T olfactometer test and completed a questionnaire survey. We reported the epidemiological burden of olfactory dysfunction and identify its demographic, behavioural and clinical correlates.Results The overall prevalence of olfactory dysfunction in the participants was 15.3%. Age (PR increased with age, ≥70 years PR = 54.70; 95% CI, 17.60–170.08; p < 0.01), rural residence (PR = 1.93; 95% CI, 1.76–2.12; p < 0.01), current smoking (PR = 1.20; 95% CI, 1.04–1.39; p < 0.01) and self-reported olfactory dysfunction (PR = 3.97; 95% CI, 3.61–4.37; p < 0.01) were independently associated with a higher prevalence of olfactory dysfunction, while being female (PR = 0.78; 95% CI, 0.71–0.85; p < 0.01), having more years of education (High school PR = 0.60; 95% CI, 0.54–0.66; College and above PR = 0.45; 95% CI, 0.38–0.52; p < 0.01), and higher income level (p < 0.01) were independently associated with lower prevalence.Conclusion Large-scale olfactory screening with the T&T olfactometer is viable. The prevalence of olfactory dysfunction demonstrates a progressive increase with advancing age. Independent factors associated with olfactory dysfunction include male gender, residing in rural areas, having lower educational levels, low income, current smoking and self-reported olfactory dysfunction.