Poor Olfaction and Risk of Stroke in Older Adults: The Atherosclerosis Risk in Communities Study.

Background: Poor olfaction may be associated with adverse cerebrovascular events, but empirical evidence is limited. We aimed to investigate the association of olfaction with the risk of stroke in the Atherosclerosis Risk in Communities Study.

Methods: We included 5799 older adults with no history of stroke at baseline from 2011 to 2013 (75.5±5.1 years, 59.0% female and 22.2% Black). Olfaction was assessed by the 12-item Sniffin' Sticks odor identification test and defined as poor (number correct ≤8), moderate (9-10), or good (11-12). Participants were followed from baseline to the date of the first stroke, death, last contact, or December 31, 2020, whichever occurred first. We used the discrete-time subdistribution hazard model to estimate the marginal cumulative incidence of stroke across olfactory statuses and adjusted risk ratios, accounting for covariates and competing risk of death.

Results: After up to 9.6 years of follow-up, we identified 332 incident stroke events. The adjusted marginal cumulative incidence of stroke at 9.6-year follow-up was 5.3% (95% CI, 4.2%-6.3%), 5.9% (95% CI, 4.8%-7.1%), and 7.7% (95% CI, 6.5%-9.1%) for good, moderate, and poor olfaction, respectively. Compared with good olfaction, poor olfaction was significantly associated with higher stroke risk throughout follow-up, albeit the association modestly attenuated after 6 years. Specifically, the adjusted risk ratios were 2.14 (95% CI, 1.22-3.94) at year 2, 1.98 (95% CI, 1.43-3.02) at year 4, 1.91 (95% CI, 1.43-2.77) at year 6, 1.49 (95% CI, 1.17-2.00) at year 8, and 1.45 (95% CI, 1.16-1.95) at year 9.6. Results were robust in multiple subgroup and sensitivity analyses.

Conclusions: In older adults, poor olfaction assessed by a single olfaction test was associated with the higher risk of stroke in the next 10 years.