Association Between Poor Olfaction and Lower Pulmonary Function in Older Adults

Olfaction may be associated with lung health because of the anatomic and functional connections between the upper and lower airways, but empirical evidence is lacking.

Is poor olfaction associated with lower pulmonary function in older adults?

This study included 1,951 participants from the Health, Aging, and Body Composition Study who completed the 12-item Brief Smell Identification Test (B-SIT) in clinical visit year 3 (1999-2000) and at least 1 valid spirometry test in the year 5, 8, or 10 clinical visits. The mean (SD) age at the baseline spirometry test was 74.4 (2.8) years. Olfaction was categorized as good (B-SIT score, 11-12), moderate (B-SIT score, 9-10), or poor (B-SIT score, 0-8). We used multivariable joint models to assess the associations of olfaction with FEV₁, FVC, and FEV₁ to FVC ratio. In addition, we assessed whether olfaction was associated with the participants' ability to carry out or complete the spirometry test.

Participants with poor olfaction demonstrated lower FEV₁ and FVC at all 3 clinical visits from years 5 through 10. For example, in year 5, compared with those with good olfaction, FEV₁ was on average 44.0 mL lower (95% credible interval [CrI], 8.3-79.7 mL) for participants with moderate olfaction and 63.5 mL lower (95% CrI, 25.8-101.7 mL) for those with poor olfaction. Findings were robust across sensitivity analyses. In all analyses, olfaction was not associated with the FEV₁ to FVC ratio. In addition, at each clinical visit, participants with poor olfaction were more likely to have missing or failed spirometry test results.

Our results indicate that poor olfaction is associated with worse pulmonary function in older adults. Future studies should confirm our findings and investigate potential mechanisms.