The impact of race on olfaction: A systematic review and meta‐analysis

Abstract

BackgroundMany studies have identified a higher degree of Olfactory Dysfunction (OD) in Black patients compared to White patients. This study aims to analyze olfactory outcomes in different races.MethodsThe PubMed, Scopus, and CINAHL databases were searched from inception to September 5, 2022, for English‐language articles documenting self‐reported and psychophysical OD stratified by race. A meta‐analysis of proportions, comparison of weighted proportions, and comparison of means were performed in MedCalc 20.218. In the quantitative analysis, 79,297 patients were included, comprising 79.3% Whites, 16.1% Blacks, and 4.6% Hispanics.ResultsA total of 14 studies were meta‐analyzed. The prevalence of self‐reported OD in Hispanic, White, and Black patients was 19.5% (95% CI, 16.6% to 22.6%), 17.2% (95% CI, 10.5% to 25.0%), and 13.9% (95% CI, 9.3% to 19.2%), respectively (p < 0.0007). The prevalence of psychophysical OD in Black, White, and Hispanic patients was 30.3% (95% CI, 24.2% to 36.9%), 24.2% (95% CI, 20.1% to 28.5%), and 18.4% (95% CI, 16.3% to 20.7%), respectively (p < 0.0001). Blacks reported a greater extent of unrecognized OD compared to Whites, with a difference of 16.5% (95% CI, 15.0% to 17.9%) versus 5.8% (95% CI, 3.4% to 8.0%), respectively (p < 0.0001). Hispanic rates of self‐reported OD and psychophysical OD were not statistically different.ConclusionsOur findings suggest that Blacks have the highest rate of psychophysical OD and are more likely to underreport their awareness compared to Whites.

Factors Associated with Poor Olfaction and Olfactory Decline in Older Adults in the ARIC Neurocognitive Study

“…Compared with White participants from Washington, Maryland, Black participants from Jackson, Mississippi, and Forsyth, North Carolina, had higher anosmia prevalence, consistent with prior cross-sectional reports suggesting worse odor identification ability in Blacks than in Whites [13,23,43,44]. While participants from Jackson and Forsyth overall also showed higher risks of anosmia at visit 6, we did not see faster rates of olfactory decline in these groups; these findings were comparable to one US-based study that found higher odds of poor performance in the future but not greater mean decline in Black participants than in White participants [14].…”

“…The higher burden of olfactory impairment in the Black vs. in White race is likely due to systemic socioeconomic and environmental inequities. Black individuals, compared with their White counterparts, tend to have lower education, live in poor housing conditions and areas with heavy pollution (for example, areas with poor air quality and near contaminated sites), and have more hazardous jobs [ 44 , 45 , 46 ], which are associated with olfactory impairment [ 47 ]. Furthermore, Black older adults experience a disproportionately higher burden of cognitive impairment, including dementia [ 48 ], for which olfactory impairment is an early symptom; this may also partly explain the racial differences in olfactory abilities.…”