People with olfactory impairment have more than double the odds of experiencing frailty compared to those with normal olfactory function, according to a recent meta-analysis.
A systematic review and meta-analysis, published in JAMA Otolaryngology–Head & Neck Surgery, examined the association between olfactory impairment (OI) and frailty among older adults. The study synthesized data from 10 studies, including 10,624 participants. Of the participants, 52.9% were female, with a mean age of 62.9 years (standard deviation, 9.6 years).
The analysis found that individuals with OI had 2.32-fold higher odds of frailty compared with those with normal olfactory function (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.63-3.31; I² = 0%). Additionally, the odds of OI increased with the severity of frailty. Specifically, individuals with prefrailty, frailty, and the most severe frailty had 1.55-fold (OR, 1.55; 95% CI, 1.32-1.82; I² = 0%), 2.28-fold (OR, 2.28; 95% CI, 1.96-2.65; I² = 0%), and 4.67-fold (OR, 4.67; 95% CI, 2.77-7.86; I² = 0%) greater odds of OI, respectively, compared with robust individuals.
OI was assessed using various methods, including the Brief Smell Identification Test, Sniffin' Sticks Identification Test, questionnaires, and the University of Pennsylvania Smell Identification Test.
The association between OI and frailty remained significant in subgroup analyses by geographical continent (Asia: OR, 2.24; 95% CI, 1.32-3.78; I² = 0%; Europe: OR, 2.47; 95% CI, 1.37-4.44; I² = 29%) and by the method of measuring olfactory function (objective: OR, 3.63; 95% CI, 1.74-7.55; I² = 0%; subjective: OR, 2.03; 95% CI, 1.35-3.04; I² = 0%).
The findings indicated that OI may serve as a potential biomarker for frailty. The researchers highlighted the importance of considering sensory loss in the clinical assessment of older adults. The consistent association across various methodologies and populations strengthens these findings.
The study used validated criteria to assess frailty, including the Fried Frailty Phenotype and the Frailty Index, and incorporated both objective and subjective measures of olfactory function.
The authors reported no conflict of interest. The study was funded by the National Institutes of Health.
