xRead - Olfactory Disorders (September 2023)

20426984, 2022, 4, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/alr.22929, Wiley Online Library on [04/09/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License

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research does not support cross-modality compensa tion among sensory-impaired individuals. Thresholds for detection of rotten food odor showed no differ ences between blind or deaf individuals or unimpaired controls. 72 Limited primarily subjective data suggest an increased risk of personal safety events, as well as deficits in QOL associated with fear of such events, in patients with impaired olfaction. Although appropriate interven tion studies are lacking, most authors suggest counseling impaired patients on risk-mitigation strategies as a low cost risk intervention. OD affects personal safety. Aggregate grade of evidence : C (Level 4: 14 studies; Level 5: one study). C Increased Mortality Olfaction has been linked to a number of conditions, most notably neurodegenerative disease and the ultimate health outcome: mortality. The first paper to connect impairment in odor iden tification (using the Brief Smell Identification Test, or B-SIT) with increased, adjusted risk of death was pub lished by Wilson et al 73 in 2011 in the Rush Memory and Aging Project, a prospective, longitudinal study of the development of Alzheimer disease (AD). Consequently, Gopinath et al 74 examined this question in the Blue Moun tains Eye Study in Australia. Although they found a rela tionship between the San Diego Odor Identification Test (SDOIT) score and increased risk of all-cause mortal ity, the association was not significant after adjustment for cognition. Pinto et al 75 demonstrated a robust rela tionship between poor odor identification (5-item Snif fin’ Sticks [SS] test) and odds of mortality in the National Social Life, Health, and Aging Project (NSHAP), a nation ally representative data set. Using the 40-item UPSIT R , Devanand et al 76 showed increased hazard of death for patients in the lower quartiles of function compared with those in the highest quartile in a multiethnic commu nity cohort from New York City, using the Washington Heights/Inwood Columbia Aging Project. Schubert et al 77 examined data from EHLS (Epidemiology of Hearing Loss Study), a population-based longitudinal study of sensory function and aging in Beaver Dam, WI, and found that sensory dysfunction predicted mortality but was specific to olfaction (8-item SDOIT) and not hearing or vision. Ekström 78 expanded on these findings using data from the Betula project, a Swedish population–based longitudinal study of aging, memory, and health, and determined that the relationship between decreased odor identification

(13-item Scandinavian Odor-Identification Test [SOIT]) was not mediated by conversion to dementia before death, suggesting that the mechanism was not solely via the development of neurodegenerative disease. Similarly, examining underlying mechanisms, Leschak et al 79 found that social network size partially mediated the olfactory mortality link in women in a reanalysis of NSHAP data, implicating social context. Laudisio et al 80 found that OD (self-reported inability to detect at least two of three com mon odors) was associated with reduced survival, an asso ciation that varied according to frailty and systemic inflam mation (serum increased interleukin [IL] 6 levels) in a prospective population-based study of the development of late-life disability in Tuscany, Italy, (InChianti [Invecchiare in Chianti] study). Recently, Liu et al 81 found a close con nection between decreased odor identification (B-SIT) and death in the Health, Aging, and Body Composition study, which examined older adults from Pittsburgh, PA, and Memphis, TN. Interestingly, they identified neurodegen erative and cardiovascular diseases as key outcomes and showed that neurodegenerative diseases explained only 22% and weight loss explained only 6% of the higher 10 year mortality among participants with poor olfaction. This study had the longest follow-up. Finally, Choi et al 82 linked 2013–2014 National Health and Nutrition Examina tion Survey (NHANES) participants to the National Death Index and found that objective olfactory impairment pre dicted 5-year mortality in patients aged ≥ 65 years but not in middle-aged patients after adjusted analyses. These studies are all of sizable cohorts and include diverse older adult participants in a variety of popula tions across the world, with specific inclusion and exclu sion criteria. All (excepting the InChianti study) objec tively assessed odor identification. We note that they do so in completely different ways using different forms of testing, both long and short. All studies controlled for key confounding factors and all include objective measures. The analysis strategy varies among the studies (eg, logis tic regression, cox analyses, and hazard ratios). Neverthe less, almost all of these studies found robust (excepting the Blue Mountains Eye study) and consistent relationships between poor olfaction and subsequent mortality (time to follow-up ranged from 4.1 to 13 years). Several provide dose- response analyses. Thus, the aggregate LOE support ing a connection between olfaction and death is B (over whelming consistent evidence from 9 observational stud ies, all Level 2). These conclusions are viewed as extremely strong given the inability to perform randomized trials for this question. Decrease in olfaction is associated with increased mortality. Aggregate grade of evidence : B (Level 2: 10 studies).