Olfactory Dysfunction in a Mexican Population Outside of COVID-19 Pandemic: Prevalence and Associated Factors (the OLFAMEX Study)

PURPOSE OF REVIEW: To study the prevalence of olfactory loss and its associated factors in a Mexican population a cross-sectional analytical study based on a population interviewed about health, epidemiologic aspects, and sense of smell (tested with four scents: rose, banana, perfume, and gas) was conducted to evaluate olfactory detection, memory, and identification. Levels of sense of smell perception were determined when the participants detected, recognized, or identified all (normosmia), 1–3 (hyposmia), or none (anosmia) of the odorants. Associated factors of olfactory dysfunction were identified by multivariate analysis (odds ratio, 95%CI). RECENT FINDINGS: Olfactory dysfunction is a prevalent disorder affecting up to 20% of the general population. In addition to viral infection, including COVID-19, a number of other causes and factors may also be involved. SUMMARY: 1,956 surveys were conducted and 1,921 were analyzed. Most of the participants (62.1%) were women. The general prevalence of olfactory dysfunction, regarding detection, was 7.2% (7.1% hyposmia, 0.1% anosmia). Age-related olfactory deterioration was observed in both sexes from the 5th decade of life (OR 2.74, p = 0.0050). Women showed better olfactory identification (OR 0.73, p = 0.0010). Obesity (OR 1.97, p = 0.0070), low educational level, bad/very bad self-perceived olfactory function (OR 2.74, p = 0.0050), olfactory loss for less than one week (OR 1.35, p = 0.0030), exposure to toxics/irritants (OR 1.31, p = 0.0030), active smoking (OR 1.58, p < 0.0010), and type 2 diabetes mellitus (OR 2.68, 95%CI 1.74–4.10, p < 0.0001) were identified as factors associated with olfactory dysfunction. These results in a Mexican population suggest better olfactory identification (verbalization) in females. Age was a determining factor in the olfactory deterioration process and obesity and diabetes mellitus were also associated with olfactory disorders. Finally, these findings reinforce the differential diagnosis with other potential causes of sense of smell loss, during the COVID-19 outbreak.